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Periapical Radiolucency And Radiopacity Important Notes

• Multilocular radiolucencies – 3 types
  • Soap bubble:- Individual compartments are circular, large and overlapped
  • Honeycomb:- Individual compartments are small, numerous, and equally spaced.
  • Angular:- Individual compartments are angular in shape
• Common lesions showing multilocular radiolucency:
  • Ameloblastoma
  • Odontogenic keratocyst
  • Odontogenic myxoma
  • Central giant cell granuloma
  • Central hemangioma
  • Aneurysmal bone cyst
  • Cherubism
• Ameloblastoma:
  • Soap bubble or honeycombed appearance
  • Most common in 3rd molar – ramus area
  • Nothing is seen in the advancing end of the tumor
  • Root resorption and displacement of adjacent teeth are seen
  • Rarely causes perforation
• Odontogenic Keratocyst:
  • Soap bubble appearance
  • No expansion of cortical plates, because the lesion grows anterior-posteriorly
• Odontogenic myxoma:
  • Exclusively seen in jaws, only in tooth-bearing portions
  • Angular or tennis racket or honeycomb appearance
  • May be found in association with impacted tooth

Periapical Radiolucency And Radiopacity Long Essays

Question 1. Enumerate periapical radiolucencies and opacities. How would you diagnose systemic diseases with periapical changes in radiographs?
Answer.

Periapical Radiolucencies:

• True periapical radiolucencies
  • Pulpoperiapical Radiolucencies:
    • Periapical granuloma:
    • Radicular cyst
    • Periapical scar
    • Chronic and acute dentoalveolar abscess:
    • Surgical defect
    • Osteomyelitis
    • Pulpoperiapical disease
  • Dentigerous Cyst
  • Periapical Cementosseous Dysplasis:
  • Periodontal Disease
  • Traumatic Bone Cyst
  • Non radicular Cyst
  • Malignant Tumors
• Rarities:
  • Ameloblastoma
  • Aneurysmal bone cyst
  • Cementifying and ossifying fibroma
  • Cementoblastoma – early stage
  • Giant cell granuloma
  • Leukemia

Periapical Radiopacities:

• True Periapical Radiopacities:
  • Condensing or sclerosing osteitis
  • Periapical idiopathic osteosclerosis
  • Periapical or focal cement osseous dysplasia
  • Unerupted succedaneous teeth
  • Foreign bodies
  • Hypercementosis
  • Rarities
  • Calcifying odontogenic cyst
  • Cementoossifying fibroma
  • Chondroma
  • Hematoma
  • Mature cementoblastoma
  • Osteogenic sarcoma
• False Periapical Radiopacities:
  • Anatomic structures
  • Impacted teeth
  • Tori, exostosis
  • Retained root tips
  • Foreign bodies
  • Mucosal cyst of the maxillary sinus
  • Ectopic calcification
  • Rarities
  • Calcified acne lesions
  • Calcified hematoma
  • Calcifying odontogenic cyst
  • Squamous cell carcinoma
  • Tonsilloliths

Systemic Diseases With Periapical Changes:

• Hyperparathyroidism:
  • There is a loss of lamina dura
  • Depending on the duration and severity, loss of lamina dura may occur around one tooth or all remaining teeth
  • Loss may be complete or partial
  • It results in a tapered appearance of the root
• Hypoparathyroidism:
  • Reveals dental enamel hypoplasia
  • External root resorption
  • Delayed eruption
  • Root dilaceration
• Hyperpituitarism:
  • Hypercementosis present over roots of posterior teeth
• Hypopituitarism:
  • Third molar buds are completely absent
• Hyperthyroidism:
  • Excessive bone resorption is seen
• Hypothyroidism:
  • Show periodontal disease, loss of teeth, and external root resorption
• Diabetes mellitus:
  • Presence of bone loss due to more prone to periodontal diseases
  • Results in focal sclerosing osteomyelitis or dry socket
• Cushing’s syndrome:
  • Teeth may erupt prematurely
  • Partial loss of lamina dura may occur

Read And Learn More: Oral Radiology Question and Answers

• Osteoporosis:
  • Thinning of the inferior mandibular cortex
  • Reduction in the number of trabeculae
• Rickets:
  • Enamel hypoplasia
  • Involves both unerupted and erupted teeth
  • Lamina dura and cortical boundary of tooth follicles may be thin or missing
• Renal Osteodystrophy:
  • Hypoplasia and hypo calcification of teeth
  • Results in loss of enamel
  • Lamina dura may be absent or less apparent
• Hypophosphatemic rickets:
  • Teeth are poorly formed with thin enamel caps large pulp chambers and root canals
  • Presence of periapical and periodontal abscesses
  • Subsequent pulp necrosis may be present
  • Lamina dura may become sparse
  • Cortical boundaries around tooth crypts may be thin or absent
• Hypophosphatasia:
  • Both primary and permanent teeth have thin enamel layers large pulp chambers and root canals
• Osteopetrosis:
  • Teeth are poorly calcified
  • Ankylosis is seen
  • Lamina dura and cortical borders may appear thicker than normal
• Systemic sclerosis:
  • Increase in width of periodontal ligament spaces around teeth
  • Both anterior and posterior teeth are affected
• Sickle cell anemia:
  • Thinning of cortical plates
• Thalassemia:
  • Thinning of cortical borders
  • Enlargement of marrow spaces
  • Trabeculae are large and coarse
  • Lamina dura is thin and the roots of teeth may be short

Question 2. Describe differential diagnosis of radiolucencies on the coronal part of teeth
Answer.

Pericoronal Radiolucencies:

With radiopaque flecks

• Ameloblastic fibro – odontoma
• Adenomatoid odontogenic tumor
• Calcifying epithelial odontogenic tumor
• Calcifying odontogenic cyst

Without radiopaque flecks

• • Normal follicular space
  • Osteitis with pericoronitis
  • Dentigerous cyst
  • Ameloblastic fibroma

Question 3. Describe the differential diagnosis of radiolucent lesions in the posterior part of the body of the mandible.
Answer.

Radiolucent Lesions In the Posterior Part Of The Body Of the Mandible:

• Traumatic bone cyst
• Odontogenic keratocyst
• Ameloblastoma
• Cherubism
• Odontogenic myxoma
• Aneurysmal bone cyst
• Central hemangioma

Question 4. Discuss the differential diagnosis of periapical radiolucencies.
Answer.

True periapical radiolucencise:

• Pulpoperiapical Radiolucencies:
  • Periapical granuloma:
    • The lesion has well-circumscribed radiolucency
    • It is somewhat rounded surrounding the apex of the tooth
    • This may have thin radiopaque borders
    • The involved may show deep restorations, extensive caries, fractures, or narrower pulp canals
    • Its size is less than 2.5 cm in diameter
  • Radicular cyst:
    • It appears as a round or pear-shaped radiolucency at the apex of a nonvital tooth
    • The radiolucency is more than 1.5 cm, but less than 3 cm in diameter, with a well defined hyperostotic borders
    • The margins are smooth, well-defined, well-etched and continuous
    • A radiopaque line of corticated bone is seen surrounding it
    • The radiopaque border is continuous with lamina dura
    • It may cause resorption of the roots
    • The adjacent teeth are displaced
    • There may be Buccal expansion
    • There may be displacement of the antrum
  • Periapical scar:
    • A well-circumscribed radiolucency, that is smaller than granuloma and cyst
    • The scar is constant in size
  • Chronic and acute dentoalveolar abscess:
    • The radiolucency may vary in size from small to quite large
    • The initial lesion may even cause expansion of the jaws
    • The margins may vary from well-defined to poorly defined-borders
    • The involved tooth may show deep restorations, caries, narrowed pulp canals
    • The roots may even show resorption
  • Surgical defect:
    • The radiolucency is usually rounded
    • It is smooth-contoured
    • It has well-defined borders
    • It usually doesn’t measure more than 1 cm in diameter
    • The radiolucency usually decreases in size
  • Osteomyelitis:
    • The density of the Involved bone is decreased
    • Loss of sharpness of trabeculae
    • Outline becomes blurred
    • Gradually solitary or multiple radiolucent areas may be seen on the radiograph representing enlarged trabeculae spaces
    • Saucer saucer-shaped area of destruction with irregular margins with teeth and some supporting bone is seen
    • Inflammatory exudates may lift the periosteum, which is seen as a radiopaque line adjacent to and almost parallel or slightly convex to the surface
    • There is a loss of continuity of lamina dura
  • Pulpoperiapical disease:
    • These appear as gray shadows that may be dome-shaped in the maxillary floor or a gray radiopacity that appears as a cap over the adjacent root
    • The margin is usually smooth contoured and distinct
• Dentigerous Cyst:
  • It appears as well defined radiolucent lesion with a hyperostotic border associated with the crown of unerupted teeth
  • It is usually unilocular
  • It may envelop the crown symmetrically or may expand laterally
  • The associated tooth may be displaced
  • The outline of the larger cyst may expand from the ramus into the coronoid process or the condyle
  • There may be resorption of the adjacent teeth
  • Types:
    • Central
      • The crown is enveloped symmetrically
    • Lateral
      • Cyst results from the dilatation of the follicle on one aspect of the crown
    • Circumferential
      • This entire tooth is surrounded by the cyst
• Periapical Cementosseous Dysplasia:
  • In the early stage, it occurs as radiolucencies that are usually somewhat rounded
  • They have well-defined borders
  • They are associated with vital pulp
  • The lesions may be solitary or multiple
  • They exceed 1 cm in diameter
• Periodontal Disease:
  • Radiolucency is caused by advanced bone loss
  • The entire bony support is lost
  • The tooth may appear as floating in the radiolucency
• Traumatic Bone Cyst:
  • The lesion exceeds size efficient to cause expansion of the cortical plates
  • This produces a bony hard bulge on the jaws
  • The lamina dura is intact
  • The radiolucency is well-defined
  • It is round to oval in shape
  • The lateral and inferior borders of the elongated variety have smooth, regular borders
• Non Radicular Cyst:
  • The most common structures seen are incisive canal cysts, median mandibular cysts, and primordial cyst
• Malignant Tumors:
  • It may be found as a single periapical radiolucency
  • Expansion of the jaw occurs in advanced conditions
  • The expansion has a smooth surface covered with a normal structure
• Rarities:
  • Ameloblastoma
  • Aneurysmal bone cyst
  • Cementifying and ossifying fibroma
  • Cementoblastoma – early stage
  • Giant cell granuloma
  • Leukemia

Periapical Radiolucency And Radiopacity Short Essays

Question 1. Differential diagnosis of periapical radiopacities.
Answer.

True Periapical Radiopacities:

• Condensing or sclerosingosteitis:
  • The lesion is of variable size with margins that are well-defined or diffuse
  • At the diffuse margins, the thickened trabeculae can be seen in continuation with the normal adjacent trabeculae
  • The image is seen outside the lamina dura and periodontal spaces outlining the root
• Periapical idiopathic osteosclerosis:
  • There may be solitary, multiple
  • It may be unilateral or bilateral
  • It may vary in size from 2 mm to cm in diameter
  • May have a round or irregular shape
  • The border may be distinct to indistinct, ragged, or blending with the adjacent bone
  • Commonly seen in the mandible
  • Sometimes deciduous molar roots are resorbed and replaced by sclerotic bone
• Peripheral or focal cement osseous dysplasia:
  • It is predominantly round or oval with smoothly contoured borders
  • It varies in diameter from 0.5 to 2 cm
  • The mature lesion is uniformly dense
  • It may have a thin radiolucent border
  • The border may be vague
  • Adjacent root shows hypercementosis
• Unerupted succedaneous teeth:
  • The crowns of permanent teeth represent radiopacity
  • Seen in patients under 12 or 13 years of age
• Foreign bodies:
  • Radiopaque foreign bodies in the peri-apex is usually root canal-filling material
• Hypercementosis:
  • The premolars are more often affected
  • It may be confined to just a small region on the root producing a nodule or the whole root may be involved
  • The altered shape of the root is apparent
  • The root is surrounded by a normal periodontal ligament space and lamina dura
  • On the anterior tooth, it may appear as a spherical mass of cementum attached to the root end
• Rarities:
  • Calcifying odontogenic cyst
  • Cementoossifying fibroma
  • Chondroma
  • Hamartoma
  • Mature cementoblastoma
  • Osteogenic sarcoma

False Periapical radiopacities:

• Anatomic structures:
  • It includes the anterior nasal spine, malar process, external oblique ridge, mylohyoid ridge, mental protuberance, and hyoid bone
  • Impacted teeth
    • It may be situated directly at the apex of an erupted tooth
  • Tori, exostosis,
    • It may appear as a single or multiple lesion
    • It is smoothly contoured, somewhat rounded, dense radiopaque masses
    • These are not circumscribed by periodontal ligament and lamina dura
  • Retained root tips
    • They are projected over the apex of adjacent teeth
    • The shape of the root, root canal, periodontal ligament, and lamina dura remain unaltered
  • Foreign bodies
    • Examples of such objects are metal fragments, zippers, hooks, jewelry, etc.
  • Mucosal cyst of the maxillary sinus
    • It appears relatively dense, dome-shaped mass with its base on the floor of the sinus
  • Ectopic calcification
    • It includes
    • Sialoliths
    • Rhinoliths
    • Antroliths
    • Calcified lymph nodes
    • Phleboliths
    • Anterial calcification
  • Rarities:
    • Calcified acne lesions
    • Calcified hematoma
    • Calcifying odontogenic cyst
    • Squamous cell carcinoma
    • Tonsilloliths

Question 2. Differential diagnosis of multiple punched-out radiolucencies.
Answer.

Multiple Myeloma:

• They are usually bilateral
• It is seen in the mandibular posterior region and ramus
• It arrears as a small rounded and discrete radiolucency having punched out appearance
• There may be numerous areas of bone destruction within the region of generalized radiolucency
• Some lesions have an oval and cystic shape
• It has well-defined margins
• The border may have a thin sclerotic rim
• It has well-defined margins
• The border may have a thin sclerotic rim
• The lesion may vary in size
• The teeth may appear too opaque
• The mandibular lesion may cause thinning of the cortical lower border

Cherubism

• It occurs bilaterally on rami
• The lesion grows slowly expanding but not perforating the cortex
• Usually, bony architecture returns to normal except for some that resemble ground glass appearance

Metastatic Carcinoma:

• It defined radiolucency
• It is seen in the mandible
• There may be multiple punched-out radiolucency when several nests of tumor cells are located close to each other
• There is a widening of PDL
• The cortical structures are destroyed

Periapical Radiolucency And Radiopacity Short Answers

Question 1. Periapical radiopacities.
Answer.

True Periapical Radiopacities:

• Condensing or sclerosing osteitis:
  • At the diffuse margins, the thickened trabeculae can be seen in continuation with the normal adjacent trabeculae
• Periapical idiopathic osteosclerosis:
  • May have a round or irregular shape
  • The border may be distinct to indistinct, ragged, or blending with the adjacent bone
  • Commonly seen in the mandible
• Periapical or focal cement osseous dysplasia:
  • It is predominantly round or oval with smoothly contoured borders
• Unerupted succedaneous teeth:
  • The crowns of permanent teeth represent radiopacity
  • Seen in patients under 12 or 13 years of age
• Foreign bodies:
  • Radiopaque foreign bodies in the periapex are usually root canal-filling material
• Hypercementosis:
  • It may be confined to just a small region on the root producing a nodule or the whole root may be involved
  • The altered shape of the root is apparent
• Rarities:
  • Calcifying odontogenic cyst
  • Cementoossifying fibroma
  • Chondroma
  • Hamartoma
  • Mature cementoblastoma
  • Osteogenic sarcoma

False periapical Radiopacities:

• Anatomic structures:
  • It includes the anterior nasal spine, malar process, external oblique ridge, mylohyoid ridge, mental protuberance, and hyoid bone
• Impacted teeth:
  • It may be situated directly at the apex of an erupted tooth
• Toxic, exostosis:
  • It is smooth contoured, somewhat rounded, dense radiopaque masses
• Retained root tips:
  • They are projected over the apex of adjacent teeth
• Foreign bodies:
  • Examples of such objects are metal fragments, zippers, hooks, jewelry, etc.
• Mucosal cyst of the maxillary sinus:
  • It appears relatively dense, dome-shaped mass with its base on the floor of the sinus
• Ectopic calcification:
  • It includes
  • Sialoliths
  • Rhinoliths
  • Antroliths
  • Calcified lymph nodes
  • Phleboliths
  • Arterial calcification
• Rarities:
  • Calcified acne lesions
  • Calcified hematoma
  • Calcifying odontogenic cyst
  • Squamous cell carcinoma
  • Tonsilloliths

Question 2. Radiographic features of cherubism
Answer.

Radiographic features of cherubism

• The involved area shows well-defined, multilocular, cyst-like radiolucent areas
• These often coalesce to form larger lesions
• Later stages cause severe bilateral expansion of the jaw with thinning of cortical plates
• Presence of ground-glass appearance
• Displacement of the inferior alveolar canal
• Multiple unerupted and displaced teeth appear
• Cortical perforations may occur

Radiographic Interpretations

Important Notes

• Some of the radiographic appearances in various pathology

• Central giant cell granuloma:
• • It is a reactive process, but not a neoplasm.
  • Soap bubble or honeycomb appearance
  • A characteristic feature is that the septa are perpendicular to the periphery of the lesion and notching is seen corresponding to the outline where the septa arise.
• Central hemangioma:
  • Soap bubble appearance
  • Swelling of jaws, and gingival bleeding through the sulcus are seen.
  • “Pumping action” is a characteristic clinical feature. If the tooth in the region of the tumor is pushed into the tumor, it will rebound back to the original.
• Aneurysmal bone cyst:
  • H/O of trauma, the cyst is a reactive process secondary to trauma
  • Honeycomb and soap bubble appearance
  • Frank’s blood on aspiration
  • Pseudocyst
  • Multinucleated giant cells are seen histologically
• Cherubism:
  • Seen at 2 – 6 years of age with familiar history
  • When the maxilla is involved, the skin over it is stretched with the pulling of skin below the eyes. The sclera is visible giving an “angelic look” or “eyes towards heaven”.
  • Multiple unerupted teeth are seen which appear to be floating in cyst-like spaces.
• Lesions arising from clinically missing or radiologically missing teeth:
  • Eruption cyst
  • Dentigerous cyst
  • Gorlin cyst
  • Unicystic or mural ameloblastoma
  • Adenoamelobastoma
  • Ameloblastic fibroma
  • Variants of ameloblastoma
    • Ameloblastic Odontoma
    • Ameloblastic Odontofibroma
    • Ameloblastic dentinoma
    • Ameloblastic dentinofibroma
  • Primordial cyst
  • Teratoma

Radiographic Interpretations Long Essays

Question 1. Describe the radiographic appearance of different cysts of the maxilla and mandible.
Answer.

Cysts Of Jaws:

• Odontogenic cysts:
• • Radicular cyst
  • Dentigerous cyst
  • Residual cyst
  • Odontogenic keratocyst
  • Calcifying odontogenic cyst
  • Primordial cyst
  • Globulomaxillary cyst
  • Median mandibular cyst
• Non – Odontogenic Cysts:
  • Incisive canal cyst
  • Nasoalveolar cyst
  • Median palatine cyst
  • Traumatic bone cyst
  • Aneurysmal bone cyst

Question 2. Describe the radiographic appearance of different stages of osteomyelitis of the jaw
Answer.

Osteomyelitis:

Early Acute:

• No radiographic changes are absorbed

Established Suppurative:

• The density of the involved bone is decreased
• Loss of sharpness of trabeculae
• Outline becomes blurred
• Gradually solitary or multiple radiolucent areas may be seen on the radiograph representing enlarged trabeculae spaces
• Saucer saucer-shaped area of destruction with irregular margins with teeth and some supporting bone is seen
• Inflammatory exudates may lift the periosteum, which is seen as a thin radiopaque line adjacent to and almost parallel or slightly convex to the surface
• There is a loss of continuity of lamina dura

Chronic Type:

• Multiple radiolucencies of variable size with irregular outlines and poorly defined borders are seen
• The bone gradually develops a moth-eaten appearance, as radiolucent areas enlarge and are separated by islands of normal bone
• Segments of the necrotic bone become detached and calcified and are called sequestra
• Sequestra are more dense and better defined due to sclerosis

Read And Learn More: Oral Radiology Question and Answers

• It often stimulates the formation of periosteal new bone which is seen as a single radiopaque or a series of radiopaque lines parallel to the surface of the critical bone gradually the radiolucent strip that separates the new bone from the outer cortical bone may be filled with sclerotic bone
• Roots may undergo resorption
• Lamina dura becomes less apparent
• The Fistula tract may appear as a radiolucent band

Radiographic Interpretations Short Essays

Question 1. Radiographic features of periodontal disease
Answer.

Early Or Mild Periodontitis:

• It is represented as an area of localized erosion of the alveolar bone crest
• In the anterior region, it is seen as the blunting of the alveolar crests
• In the posterior region, there may be a loss in the sharp angle between the lamina dura and the alveolar crest
• There is a loss of the cortical margins
• It appears rounded off with irregular diffuse margins

Moderate Periodontitis:

• The Buccal and lingual cortical plates are resorb
• There may be bone defects of bone between both plates
• It is seen as generalized horizontal bone erosion or localized angular defect

Horizontal Bone Loss:

• There is a loss of height of the alveolar bone with the crest still horizontal or parallel to the occlusal plane

Vertical Osseous Defect:

• These are localized lesions
• They appear as an oblique angulation of the alveolar bone in the area of the involved teeth

Types:

• Interproximal craters
• Proximal intrabony defect
• Two walled defects
• Interproximal hemisepta
• Inconsistent bony margins

Surrounding Internal Bone Changes:

• Peripheral bone may appear radiolucent due to loss of density and number of trabeculae
• The sclerotic bone appears as a dense amorphous radiopaque mass

Advance Or Severe Periodontitis:

• Extensive bone loss
• Excessive mobility
• Extensive osseous defects

Furcation Involvement:

• Bone resorption extending down the side of the multirooted tooth
• The thickening of the periodontal ligament space at the apex of the inter radicular bone crest
• The radiolucent image is sharply outlined between the roots
• The cortical plates appear more irregular

Aggressive Periodontitis:

Types:

• Localized juvenile periodontitis
• • Associated with attachment loss
  • Vertical bone loss with maxillary teeth (incisors & / molars)
  • There are arch or saucer-shaped defects with strong arch symmetry
• Generalized juvenile periodontitis
  • It may involve a variable number of teeth
  • A Rapid bone loss which may be of the vertical angular or horizontal pattern is seen
• Progressing periodontitis

Tooth Mobility:

• In the case of the single tooth, it may develop an hourglass-shaped
• In multirooted teeth, widening of periodontal space is seen

Question 2. Radiographic features of dental caries
Answer.

Dental Caries Types:

• Proximal Caries:
  Types:

• • Incipient proximal lesions:
    • It appears as a classical triangle with its broad base at the tooth surface spreading along the enamel rods
    • It appears as a notch, a dot, a band, or a thin line
  • Moderate proximal lesion:
    • These involve more than the outer half of the enamel
    • It doesn’t extend upto DEJ
    • Different appearances:
      • Triangular in shape with the base at the surface of the tooth
      • Diffuse radiolucent image
      • Combination of the above
  • Advanced proximal lesions:
    • These depict lesions invading the DEJ
    • It appears triangular and diffuse
    • This is the spreading of the demineralization process
    • Usually, the lesion does not spread beyond more than half the thickness of the dentine
• Pit And Fissure Caries:
  Types:

• • Incipient Occlusal Lesions:
    • These are not usually detected on the radiograph unless the lesion reaches the dentin
    • The only change is seen as a grey shadow just below the DEJ
  • Moderate Occlusal Lesions:
    • It appears as a broad base thin radiolucent zone in the dentine with little or no change apparent in the enamel
    • Occlusal caries in dentine appears as a band of increased opacity between the carious lesion and the pulp chamber
  • Severe Occlusal Lesions:
    • Depict large cavity in the crown
    • Pulp exposure is looked for
• Buccal/Facial/Lingual/Cervical Caries:
  • These occur in enamel pits and fissures
  • They appear as small round radiolucencies and become elliptical or semilunar as the lesion enlarges they have sharp well-defined borders
  • Surrounded by apparent radiolucency
  • If the lesion extends up to the distal line angle it may appear as a proximal caries
• Root Surface Caries:
  • It involves both cementum and dentin
  • It is common in mandibular molars and premolars
  • It appears as an “ill-defined saucer-like crater”
  • When the periphery surface is small it appears “notched”
• Rampant Caries:
  • Common in children with poor dietary habits and poor oral hygiene
  • It is seen as an extensive inter-proximal caries involving almost the whole of the primary dentine
• Recurrent Caries:
  • It develops at the margins of an existing restoration
  • A lesion next to the restoration may be distinguished from the radiopaque image of the restoration
• Nursing Bottle Caries:
  • The affected teeth are maxillary and Mandibular first permanent molars and the Mandibular canine
• Radiation Caries:
  • Appears as dark radiolucent shadows at the necks of teeth
  • It is more apparent in the mesial and distal aspects

Question 3. Radiographic appearance of odontoma.
Answer.

Radiographic appearance of odontoma

• Appears as well-defined radiolucencies with well-corticated borders
• Surrounded by a thin radiolucent zone representing a capsule
• • Compound – a bag of teeth appearance
    • Appears as numerous, small miniature teeth or tooth-like structures projecting from a single focus
    • Present between roots of erupted permanent teeth or above the crown of impacted teeth
  • Complex – sunburst appearance
    • Radiopaque mass within jawbone is present

Question 4. Radiographic appearance of fibrous dysplasia
Answer.

Radiographic appearance of fibrous dysplasia

• Initially, it produces unilocular or multilocular radiolucent areas in the bone
• Expansion and distortion of cortical plates occurs
• Displacement of teeth
• The egg-cell crackling of the cortex of the bone is present
• Later a classical ground glass or orange peel appearance of bone is seen
• The margin of the lesion blends with the surrounding normal bone
• Mandibular lesions cause bulging of the inferior borders
• Narrowing of periodontal ligament
• Thinning of lamina dura
• Maxillary lesions causes obliteration of maxillary sinus

Question 5. Radiographic appearance of hyperparathyroidism
Answer.

Radiographic appearance of hyperparathyroidism

• Radiodensity – Radiolucent lesion
• There may be a normal, granular, or ground-glass appearance
• Moth-eaten appearance with varying density
• Ostelitis fibrosa generalization – Localised bone destruction
• Brown tumor – represents ill-defined radiolucency
• Thinning of cortical tables
• Pepper pot skull
• Demineralization of the inferior border of the mandibular canal
• Thinning of outlines of the maxillary sinus
• Loss of lamina dura

Radiographic Interpretations Short Answers

Question 1. Radiographic features of ameloblastoma
Answer.

Radiographic features of ameloblastoma

• It develops in the Mandibular ramus region
• It may extend to the symphysis
• In the maxilla, it is more common in the third molar region and may extend into the maxillary sinus and nasal floor
• It has well defined corticated border which is curved and in small lesions, the border shape may be distinguishable from the cyst
• The internal structure varies:
• • Unilocular cyst-like appearance with a hyperostotic border
  • Area of bone destruction having smooth curved margins that are well defined, corticated, and situated within the cavity in an arrangement of coarse trabeculae
  • The thickness of the trabeculae varies from delicate strands to 2 mm width
  • In some large lesions, it is found that there is an almost complete loss of bony margins of the jaws
  • Multilocular cyst-like appearance which shows multiple cystic cavities with thin septae
  • The presence of cysts bunched together

Question 2. Radiographic features of OKC
Answer.

Radiographic features of OKC

• The radiographic appearance of odontogenic keratocyst shows aggressive growth with undulating borders, cloudy interiors, and the presence of internal septa which may give a multilocular appearance
• The margins are hyperstatic
• The size may vary from 5 cm to more in diameter
• They are usually oval shape
• It may expand and perforate the lingual and Buccal cortical plates
• Causes expansion of them
• It causes downward displacement of the inferior alveolar canal and resorption of the lower cortical plate of the mandible
• As it enlarges it may produce deflection of the unerupted teeth
• Root resorption may be seen

OKC Types:

• Envelopment
• • This embraces an adjacent unerupted teeth
• Replacement:
  • This forms in the place of normal teeth
• Extraneous
  • These are in the ascending ramus away from the teeth
• Collateral
  • These are adjacent to the roots of teeth

Question 3. Radiographic features of osteogenic sarcoma
Answer.

Radiographic features of osteogenic sarcoma

• The mandible is more frequently involved
• Common sites are the body of the mandible and the alveolar ridge
• The bony lesion is radiolucent with poorly defined, ragged borders
• Widening of PDL space
• Unusual unilateral bone resorption
• Cemental resorption
• Widening of the mandibular canal
• Early in the course of the disease, it is usually located centrally in the jaws
• Sometimes, it appears as a radiolucency in the periapex or more toward the periphery of the ridge or cortical plates
• It may originate adjacent to or seemingly in the periodontal space

Question 4. Radiographic features of proximal caries
Answer.

Proximal Caries Types:

• Incipient proximal lesions:
• • It appears as a classical triangle with its broad base at the tooth surface spreading along the enamel rods
  • It appears as a notch, a dot, a band, or a thin line
• Moderate proximal lesion:
  • These involve more than the outer half of the enamel
  • It doesn’t extend up to DEJ
  • Different appearances:
    • Triangular in shape with the base at the surface of the tooth
    • Diffuse radiolucent image
    • Combination of the above
• Advanced proximal lesions:
  • These depict lesions invading the DEJ
  • It appears triangular and diffuse
  • This is the spreading of the demineralization process
  • Usually, the lesion does not spread beyond more than half the thickness of the dentine

Question 5. Radiographic features of periapical granuloma
Answer.

Radiographic features of periapical granuloma

• Periapical area is radiolucent with loss of lamina dura
• The radiolucency may be of variable size at the apex of the tooth, usually of a diameter less than 1.5cm
• The lesion may or may not have a well-defined border
• There is a loss of lamina dura and periapical bone which is called “Periapical rarifying osteitis”
• The involved tooth may show a deep restoration, extensive caries, fracture, or a narrow pulp canal with nonvital pulp

Question 6. Radiological appearance of periapical cemental dysplasia
Answer.

Radiological appearance of periapical cemental dysplasia

The radiographic appearance of periapical dysplasia varies in different stages of the disease

• Osteolytic stage:
• • The lesion presents as a small, well-defined, radiolucent area near the apex of the involved tooth
  • Radiolucency is present in continuation with the periodontal ligament space
• Cementoblastic stage:
  • The lesion appears as a radiolucent area containing multiple small radiopaque foci
• Mature stage:
  • Present as well well-defined radiopaque mass at the root apex, being surrounded by a thin radiolucent zone

Question 7. Garre’s osteomyelitis
Answer.

Garre’s osteomyelitis

• Presents as a mottled radiolucent lesion with few radiopaque foci
• The cortex of bone exhibits many concentric or parallel opaque layers giving onion skin appearance
• It shows focal overgrowth of bone on the outer surface of the cortex
• Described as a duplication of the cortical layer of bone
• Few newly formed bony trabeculae are oriented perpendicular to onion skin layers

Question 8. Radiological appearance of fibrous dysplasia
Answer.

Radiological appearance of fibrous dysplasia

• Initially, it produces unilocular or multilocular radiolucent areas in the bone
• Expansion and distortion of cortical plates occurs
• Displacement of teeth
• The egg-cell crackling of the cortex of the bone is present
• Later a classical ground glass or orange peel appearance of bone is seen
• The margin of the lesion blends with the surrounding normal bone
• Mandibular lesions cause bulging of the inferior borders
• Narrowing of periodontal ligament
• Thinning of lamina dura
• Maxillary lesions causes obliteration of maxillary sinus

Question 9. Radiological appearance of Paget’s disease
Answer.

Radiological appearance of Paget’s disease

• Initially, there is the presence of radiolucent areas in the affected bone
• In the next stage, involved bone shows haphazardly arranged newly formed bone in radiolucent areas
• This produces the cotton wool appearance
• Radiopacity of lesions increases due to increased osteosclerosis
• Obliteration of maxillary sinus
• Hypercementosis of tooth
• Loss of lamina dura
• Obliteration of periodontal ligament space
• Root resorption

Question 10. Multilocular radiolucencies of jaws
Answer.

Multilocular radiolucencies of jaws

Multilocular radiolucencies of jaws are

• Odontogenic keratocyst
• Ameloblastic
• Central giant cell granuloma
• Cherubism
• Odontogenic myxoma
• Aneurysmal bone cyst
• Central hemangioma of bone

Question 11. Onion peel appearance
Answer.

Onion peel appearance

• It demonstrates multiple concentric parallel layers of new bone adjacent to the cortex
• The layers are thought to be the result of periods of variable growth
• It can be seen with
• • Osteosarcoma
  • Acute osteomyelitis
  • Ewing sarcoma
  • Langerhans cell histiocytosis

Question 12. Moth eaten appearance
Answer.

Moth eaten appearance

• It describes multiple small endosteal lucent lesions often with poorly defined margins
• Consists of multiple scattered holes that vary in size and arise separately
• These holes coalesce to form larger areas of bone destruction
• It is a bone marrow process
• It is seen in
• • Multiple myeloma
  • Primary bone lymphoma
  • Ewing sarcoma
  • Infection
  • Eosinophilic granuloma
  • Malignant fibrous histiocytoma
  • Metastases

Question 13. Sunburst appearance
Answer.

Sunburst appearance

• Sunburst appearance is a type of periosteal reaction giving the appearance of a sunburst secondary to an aggressive periostitis
• It occurs when the lesion grows too fast and the periosteum does not have enough time to lay down a new layer
• In such cases, the Sharpey’s fibers become stretched out perpendicular to the bone
• When these fibers ossify, they produce a pattern called a sunburst appearance
• It is frequently associated with osteosarcoma

Radiographic Interpretations Viva Voce

• A dentigerous cyst is associated with the crown of unerupted teeth
• The most common site for the occurrence of nasopalatine canal cyst is the maxillary central incisor
• AOT is commonly associated with an unerupted tooth

Specialized Radiographic Techniques Important Notes

• Xero radiography uses photoconductive selenium plates instead of film.
  • It produces images with high contrast, resolution, edge, enhancement, positive and negative display.
• Computer tomography (Axial tomography or computerized axial transverse scanning)
  • CT scanner consists of a radiographic tube that emits a finely collimated fan-shaped X-ray beam that is directed to a series of scintillation detectors or ionization chambers.
  • The CT image is recorded and displayed as a matrix of individual blocks called voxels.
  • Each square of the image matrix is called a pixel.
  • For image display each pixel is assigned with a CT number representing density.
  • These numbers are also known as Hounsfield units, which may range from – 1000 to +1000
  • Each constitutes a different level of optical density.
  • To convert a two-dimensional CT image into a three-dimensional CT image, each rectangular solid voxel is dimensionally altered into multiple cuboidal voxels.
  • This process is called INTERPOLATION.
  • IT Creates sets of evenly shaped cuboidal voxels (Aubervilliers) that occupy the same volume as the original voxel.
  • Computed tomography is useful in evaluating structures in and adjacent to salivary glands.
  • It distinguishes both soft and hard tissues as well as minute differences in soft tissue densities.
  • It is useful in assessing acute inflammatory processes and abscesses as well as cysts, mucoceles, and neoplasias.
• Salivary gland radiology:
  • Arcelin: Introduced sialography in 1913. Jacobvisi introduced the sialography technique.
  • Contrast agents used in sialography are
    • Water soluble – Eg: Pyridone, Singoaffin
    • Fat-soluble – Eg: Lipidiol, Ethiodol
  • Water-based contrast agents are used for chronic inflammatory lesions
  • Oil-based contrast agents are used in neoplasms.
  • Different projection after injection of contrast agent.
• Nuclear medicine/ scintigraphy provides a functional study of salivary glands.
  • The isotope used in the technique is “99 Tc – per technetate”.
  • All major salivary glands can be studied at once by scintigraphy.
  • It is especially advantageous for conditions in which sialography is contraindicated as well as for patients whose ducts can not be cannulated.
• Ultrasonography is a relatively inexpensive, widely available painless, easy-to-perform, and non-invasive technique.
  • The primary application of ultrasonography is for the differentiation of solids from cystic ones.
• Radiographic techniques

Read And Learn More: Oral Radiology Question and Answers

Specialized Radiographic Techniques Short Answers

Question 1. Indications and contraindications of sialography.
Answer.

Indications:

• Detection of calculus or foreign bodies
• Determination of the extent of destruction of the gland secondary to obstructing calculi or foreign bodies
• Detection of fistula, diverticula, or strictures
• Determination and diagnosis of recurrent swellings and inflammatory processes
• Demonstration of a tumor and the determination of its location, size, and origin
• Selection of a site for biopsy
• Outline of the plane of the facial nerve
• Detection of residual stones
• Sialography can be used for therapeutic procedures

Contradictions:

• Patients with known sensitivity to iodine
• During the presence of acute inflammation
• It may interfere with subsequent thyroid function tests

Question 2. Technique for transcranial view of TMJ
Answer.

Transcranial projection:

Structure Seen:

• Useful in detecting arthritis of the articular surfaces
• To evaluate the joint’s bony relationship

Film Position:

• The cassette is placed against the patient’s ear and centered over the TMJ of interest
• It is placed parallel to the sagittal plane

Patient’s Position:

• The sagittal plane must be vertical
• The ala tragus line should be parallel to the floor
• The view is taken with
  • Open mouth
  • Rest position
  • Closed mouth

Central Ray:

• It differs according to the technique
  • Postauricular
    • Point of entry is 1/2 “behind and 2” above the auditory meatus
  • Grewcock approach
    • The path of entry is through point 2 above the auditory meatus
  • Gill’s approach
    • Point of entry is 1/2 “anterior and 2” above the auditory meatus
  • Angulation: +20º To +25º
  • Point Of Exit: TMJ of interest

Question 3. Indication of sub mento vertex view.
Answer.

Indication of sub mento vertex view

• To demonstrate the base of the skull
• To examine the position and orientation of the condyle and sphenoid sinus
• To reveal the fracture in the zygomatic arch of the maxilla
• To assess the medial and lateral pterygoid plates

Question 4. Radionuclide imaging.
Answer.

Method:

• Radioactive substances should be injected intravenously into the patient
• Rectilinear scanner or gamma scintillation camera records the gamma emission from the patient
• The camera uses a scintillation crystal that can fluorescence on interaction with gamma rays emitting from the radioactive substances
• The emitting light fluorescence is detected by a photomultiplier tube that magnifies and amplifies the signals many times to produce an image

Atom Used:

• Iodine
• Gallium
• Selenium
• Technetium

Question 5. Digital imaging.
Answer.

Digital imaging

• The use of digital technology results in a 50 to 90% reduction in patient radiation exposure because of the greater sensitivity of the digital receptor

Digital Imaging Types:

• Direct digital radiography
• Indirect digital radiography

Digital imaging Uses:

• It can be used to view the images where multiple images are required for analyzing
• In endodontic practice, the root canal length, working length, and distance between obturating material and the root apex
• In periodontics, to assess and measure the height of the alveolar bone
• It can be used in a patient who is un cooperative for regular radiographic techniques
• To evaluate the bony changes in the pathology of jaws
• To detect early dental caries

Question 6. Sialography – indications
Answer.

Sialography – indications

• Detection of calculus or foreign bodies
• Determination of the extent of destruction of the gland secondary to obstructing calculi or foreign bodies
• Detection of fistula, diverticula, or strictures
• Determination and diagnosis of recurrent swellings and inflammatory processes
• Demonstration of a tumor and the determination of its location, size, and origin
• Selection of a site for biopsy
• Outline of the plane of the facial nerve
• Detection of residual stones
• Sialography can be used for therapeutic procedures

Viva Voce

• Transpharyngeal projection is used for viewing the lateral surface of the condylar head and neck
• Reverse Towne’s projection is used for viewing the posterior aspect of both the condylar head and neck
• Selenium plate is used in xeroradiography
• Water’s view is used to view maxillary sinus

Intraoral Radiographic Techniques Important Notes

• Paralleling Technique:
  • Also called as right angle or long cone technique
  • The film is placed parallel to the long axis of the teeth (object).
  • The central ray is perpendicular to both the object and the film.
  • This technique minimizes distortion, as it obeys the imaging principles.
  • The paralleling technique is the preferred method of taking IOPA
    Disadvantages
    • To position the film parallel to the teeth, the film should be placed away from the teeth making it difficult to hold without the use of film holders.
    • The increased object film distance can result in some image magnification and loss of definition by increasing the penumbra.
• Bisecting Angle Technique:
  • It is based on CIEZYNSKI’s rule of isometry
  • The film is placed closer to the teeth and is not parallel to the long axis of the teeth.
  • The central ray is perpendicular to the imaginary plane that bisects the angle formed by the film with the axis of the object
  • This arrangement inherently causes some distortion.
• Angulations for bisecting angle technique:

• Vertical angulations for child patients:

• The number of radiographs required according to age is

Intraoral Radiographic Techniques Long Essays

Question 1. Compare short-cone and long-cone techniques. Describe the technique of radiography of the lower third molar.
Answer.

Comparison of short-cone and long-cone techniques

Read And Learn More: Oral Radiology Question and Answers

Bisecting Angle Technique:

• The main difficulty is the placement of the film packet sufficiently posteriorly to record the entire third Mandibular molar and surrounding tissues, including the inferior dental canal
• The possible solutions are
  • Using a surgical needle holder to hold and position the film packet in the mouth as follows
  • The film holder is clipped securely on the top edge of the film packet
  • With the mouth open, the film packet is positioned gently in the lingual sulcus as far posteriorly as possible
  • The patient is asked to close the mouth on the handles and at the same time the film packet is eased further back into the mouth
  • The patient is asked to support the handles of the needle holder in position
  • The X-ray tube is positioned at right angles to the third molar and the film packet
  • It is centered 1 cm above the lower border of the mandible on a vertical line dropped from the outer canthus of the eye

• Taking two radiographs of the third molar using two different horizontal tube head angulations
• The film packet is positioned as posteriorly as possible
• The X-ray tube is aimed at ideal horizontal angulations
• A second film packet is placed in the same position, but the X-ray tube is positioned further posteriorly to project the apex of the third molar onto the film
• The vertical angulations are the same for both projections

Image Field:

• The projection should show the three molars

Film Placement:

• The film should be placed with the inferior border positioned beneath the lateral border of the tongue and against the lingual surface of the mandible
• The superior border should be just above the cusps of the Mandibular molars
• The anterior border should cover the mesial half of the first molar

Projection Of Central Ray:

• It Should pass through the interproximal space between the molar teeth
• The point of entry is on the cheek below, a little posterior to the lateral canthus of the eye, approximately 3cm above the inferior border of the mandible
• The central ray is angled perpendicular to the bisector through the middle of the canine with a vertical angulation of about -5 to -10 degrees

Question 2. Describe in detail about bisecting angle technique.
Or
Write a note on the principles of imaging. Describe the bisecting angle technique.
Answer.

Principle Of Imaging

• The focal spot should be as small as possible
• The focal spot-object distance should be as long as possible
• The object-film distance should be as small as possible
• The long axis of the object and the film planes should be parallel
• The X-ray beam should strike the object and the film planes at right angles
• There should be no movement of the tube, film, or patient during exposure

Bisecting Angle Technique:

• It is also called Short Cone Technique
• It is based on the principle known as “Ciesenzky’s rule of isometry”
• It states that the two triangles at equal if they have two equal angles and share a common side
• The X-ray beam should bisect the imaginary bisector that bisects the angle formed by the film and the long axis of the tooth
• When the rule is strictly followed, the resultant image obtained is accurate

Film Stabilization:

• The film-holding devices or the patient’s finger is used to position and stabilize the film
• The patient’s finger or thumb is used
• It is always placed behind the film and teeth
• The patient’s thumb is used to position maxillary films
• While index finger to stabilize Mandibular films
• The patient’s left hand is used for exposure on the right side of the mouth
• Right hand for exposure on the left side of the mouth

Guidelines:

• The white side of the film always faces the teeth
• Anterior films are always placed vertically
• Posterior films are always placed horizontally
• The incisal or occlusal edge of the film must extend approximately 1/8th inch beyond the incisal or occlusal surface of the tooth
• Always center the film over the area to be examined
• If the patient’s finger is used for stabilization, instruct the patient to gently push the film against the lingual/palatal surface of the tooth

Patient’s Position:

• Explain the procedure to the patient
• Position the patient comfortably on the chair
• Adjust the patient such that the arch being examined is parallel to the floor and the mid-sagittal plane is perpendicular to the floor
• Place and secure the lead aprons and thyroid collars
• Remove the accessories that may interfere with the exposure

Angulations:

• Horizontal angulation is achieved by directing the central ray perpendicular to the curvature of the arch to be examined

• Vertical angulations:
• Maxillary teeth
• Incisors: +40 to +50
• Canines: +45 to +55
• Premolars: +30 to +40
• Molars: +20 to +30
• Mandibular teeth
• Incisors: -15 to -25
• Canines: -20 to -30
• Premolars: -10 to -15
• Molars: -5 to 0

Basic Rules:

• Film placement: the film should be placed to cover the area of interest
• Film position – the film must be placed against the lingual surface of the tooth
• Vertical angulation: the central ray of the X-ray beam must be directed perpendicular to the image of the bisector that divides the angle formed by the film and the long axis of the tooth
• Horizontal angulation: the central beam must be directed through the contact areas between the teeth
• Film exposure – the center of the beam should be such that all the areas of the film are exposed

Advantages:

• It can be used in patients with shallow palate, bony growth
• It is quick and comfortable
• Decreased exposure time required
• Short PID is used
• If angulations are correct, the image obtained is of the same size
• No sterilization of holders is required as they are not used

Disadvantages:

• Image distortion may occur due to the use of short PID
• By using a film holder it becomes difficult to visualize the imaginary bisector
• Incorrect horizontal angulation results in overlapping
• Incorrect vertical angulation leads to elongation or foreshortening
• If the patient’s finger is used for stabilization, the patient may shift the film before or during exposure
• The patient’s hand is exposed unnecessarily
• The periodontal tissues are poorly represented
• Overlapping of shadows of Zygomatic bone occurs
• The Buccal roots of premolars and molars are foreshortened
• The crowns of the teeth are often distorted

Question 3. Enumerate types of intraoral radiographs. Describe briefly the technique of obtaining IOPA if the maxillary central incisor.
Answer.

Intraoral Radiographic Techniques:

• Periapical showing all of the tooth and the surrounding bone
• Bite-wing showing crowns of maxillary and Mandibular teeth and adjacent alveolar crests
• Occlusal shows images of the incisal edges and occlusal surfaces of teeth and cross-section of the dental arches

Technique For Obtaining Radiograph Of Maxillary Central Incisor:

• Parallel technique:
  • Image Field:
    • The film should include both the central incisors and their periapical areas
  • Film placement:
    • It should be placed at the level of the second premolars or first molars
    • The long axis should be parallel to the long axis of the maxillary central incisors
  • Projection of the Central Ray:
    • Directed high on the lip in the midline, just below the septum of the nostrils
    • Through the high of the lip in the midline, just below the septum of the nostrils
    • It should be perpendicular to the plane of the film and the roots of the teeth
  • Vertical Angulation 15 to 20:

• Bisecting angle technique:
  • Image Field:
    • It should include both the central incisors
  • Film Placement:
    • The film is placed behind the maxillary central incisors
    • It is placed in the line with the midline of the arch
    • The film is placed with the superior border extending just beyond the incisal edges of the teeth
  • Projection of Central Ray:
    • The point of entry is through the midline, through the tip of the nose, through the contact point of the central incisors
    • It should be perpendicular to the plane bisecting the angle between the long axis of the film and the roots of the teeth
      Angulation +45 to +50

Question 4. How will you take an intraoral radiograph using a long cone technique?
Answer.

• In this technique the X-ray film is placed parallel to the long axis of the tooth and the central ray of the X-ray beam is directed at right angles to the tooth and film
• The film must be placed away from the tooth and towards the middle of the oral cavity
• The object film distance must be increased
• It is also referred to as the long-cone technique

Target Film Distance:

• The target film distance is large
• This results in less image magnification and better definition

Film Holders:

• This technique requires filmholders

Film:

• Ideally, the size of the film used will depend upon the teeth being radiographed
  • Size 1: used for interiors
  • Size 2: used for posteriors

Film Placement:

• The white side of the film always faces the teeth
• For interiors, the film is placed vertically
• For posteriors, the film is placed horizontally
• The identification dot on the film is always placed toward the occlusal surface
• Always place the film away from the teeth and towards the middle of the oral cavity
• The film must be positioned to cover the prescribed area of the teeth to be examined

Patient Position:

• Explain the procedure to the patient
• Position the patient comfortably on the chair
• Adjust the patient’s head such that the occlusal place of the upper arch is parallel to the floor
• Mid sagittal plane is perpendicular to the floor
• Secure lead apron and thyroid collar
• Remove all objects from the mouth that may interfere with the film exposure

Basic Rules:

• Film placement film must cover the prescribed area of the teeth to be examined
• Film position the film must be placed parallel to the long axis of the tooth
• The holder is rotated so that the teeth to be examined are touching the block
• The correct focal spot to film distance is determined
  • In vertical angulation, the central ray of the X-ray beam is directed perpendicular to ,the film and the long axis of the tooth
  • In horizontal, regulation the central ray of the X-ray beam is directed through the contact areas of the film are exposed
  • Film exposure the X-ray beam must be centered on the film to ensure that all areas of the film are exposed

Exposure is made

Advantages:

• This technique produces an image that has dimensional accuracy
• It is simple and easy to learn and use
• It is easy to standardize and can be accurately duplicated or repeated
• Facial screens can be used
• There is decreased secondary radiation
• The shadow of the Zygomatic bone appears above the apices of the molar teeth
• The periodontal levels are well represented
• There is minimal foreshortening or elongation
• Good detection of interproximal caries
• Useful in handicapped and compromised patients as the relative position of the film packet, teeth, and X-ray beam are always maintained

Disadvantages:

• The film-holding device is difficult to place in children and patients with shallow palate
• The film-holding device causes discomfort to the patient
• Object film distance is increased
• There is an increase in the exposure time
• It is more space-consuming
• Sometimes the apices of the teeth are very close to the edge of the film and so not well appreciated
• The holders need to be autoclaved

Question 5. Discuss techniques of intraoral periapical radiographs and advantages and disadvantages
Answer.

Intraoral Periapical Techniques

Bisecting Angle Technique:

• It is also called Short Cone Technique
• It is based on the principle known as “Ciesenzky’s of isometry”
• It states that the two triangles are equal if they have two equal angles and share a common side
• The X-ray beam should bisect the imaginary bisector that bisects the angle formed by the film and the long axis of the tooth
• When the rule is strictly followed, the resultant image obtained is accurate

Bisecting Angle Technique Guidelines:

• The white side of the film always faces the teeth
• Anterior films are always placed vertically
• Posterior films are always placed horizontally
• The incisal or occlusal edge of the film must extend approximately 1/8th inch beyond the incisal or occlusal surface of the tooth
• Always center the film over the area to be examined
• If the patient’s finger is used for stabilization, instruct the patient to gently push the film against the lingual/palatal surface of the tooth

Bisecting Angle Technique Basic Rules:

• Film placement: the film should be placed to cover the area of interest
• Film position – the film must be placed against the lingual surface of the tooth
• Vertical angulation: the central ray of the X-ray beam must be directed perpendicular to the image of the bisector that divides the angle formed by the film and the long axis of the tooth
• Horizontal angulation: the central beam must be directed through the contact areas between the teeth
• Film exposure – the center of the beam should be such that all the areas of the film are exposed

Bisecting Angle Technique Advantages:

• It can be used in patients with shallow palate, bony growth
• It is quick and comfortable
• Decreased exposure time required
• Short PID is used
• If angulations are correct, the image obtained is of the same size
• No sterilization of holders is required as they are not used

Bisecting Angle Technique Disadvantages:

• Image distortion may occur due to the use of short PID
• By using a film holder it becomes difficult to visualize the imaginary bisector
• Incorrect horizontal angulation results in overlapping
• Incorrect vertical angulation leads to elongation or foreshortening
• If the patient’s finger is used for stabilization, the patient may shift the film before or during exposure
• The patient’s hand is exposed unnecessarily
• The periodontal tissues are poorly represented
• Overlapping of shadows of Zygomatic bone occurs
• The Buccal roots of premolars and molars are foreshortened
• The crowns of the teeth are often distorted

Parallel Technique

• In this technique the X-ray film is placed parallel to the long axis of the tooth and the central ray of the X-ray beam is directed at right angles to the tooth and film
• The film must be placed away from the tooth and towards the middle of the oral cavity
• The object film distance must be increased
• It is also referred to long-coming cone technique

Parallel Technique Basic Rules:

• Film placement film must cover the prescribed area of the teeth to be examined
• Film position the film must be placed parallel to the long axis of the tooth
• The holder is rotated so that the teeth to be examined are touching the block
• The correct focal spot to film distance is determined
  • In vertical angulation, the central ray of the X-ray beam is directed perpendicular to, the film and the long axis of the tooth
  • Horizontal, regulation the central ray of the X-ray beam is directed through the contact areas of the film are exposed
  • Film exposure the X-ray beam must be centered on the film to ensure that all areas of the film are exposed
• Exposure is made

Parallel Technique Advantages:

• This technique produces an image that has dimensional accuracy
• It is simple and easy to learn and use
• It is easy to standardize and can be accurately duplicated or repeated
• Facial screens can be used
• There is decreased secondary radiation
• The shadow of the Zygomatic bone appears above the apices of the molar teeth
• The periodontal levels are well represented
• There is minimal foreshortening or elongation
• Good detection of interproximal caries
• Useful in handicapped and compromised patients as the relative position of the film packet, teeth, and X-ray beam are always maintained

Parallel Technique Disadvantages:

• The film-holding device is difficult to place in children and patients with shallow palate
• The film-holding device causes discomfort to the patient
• Object film distance is increased
• There is an increase in the exposure time
• It is more space-consuming
• Sometimes the apices of the teeth are very close to the edge of the film and so not well appreciated
• The holders need to be autoclaved

Intraoral Radiographic Techniques Short Answers

Question 1. Indicates for bitewing technique.
Answer.

Indicates for bitewing technique

• Detection of interproximal caries
• Monitoring the progression of dental caries
• Detection of secondary caries
• Evaluating periodontal conditions
• Useful for evaluating alveolar bone crest and changes in height
• For detecting calculus deposited in the interproximal areas

Question 2. Angulations for upper molar.
Answer.

Angulations for upper molar

• For the bisecting angle technique
• Universal standard +20 to +30
• Indian standard +30
• For parallel technique
• It is perpendicular to the film
• For bitewing technique
• The central ray is directed at +10 degrees to the occlusal plane

Question 3. Duplicate radiographs.
Answer.`

Duplicate radiographs

• Used to separate patient’s records, insurance party, and third-party requirements

Types of methods used for it

• Photographic method
  • Most common method
  • Film is exposed to a source of light and then subjected to transillumination
  • A radiograph is placed between the light source and the film
• Double film packet
  • Used for intraoral and extraoral films
• Radiographic method
  • X-rays and intensifying screens are used
  • In this, the intensifying screens should be kept above, then reverse film, and then unexposed film.

Faulty Radiographs Important Notes

• Image shape distortion can be minimized by:
  • Positioning the film parallel to the long axis of the object.
  • Orienting the central ray perpendicular to the object and film.
• Causes of image foreshortening:
  • The central ray is perpendicular to the film but not to the object.
  • More positive vertical angulation
• Cause of image elongation:
  • The central ray is perpendicular to the object but not to the film.
  • More negative vertical angulation.
• Common problems

Read And Learn More: Oral Radiology Question and Answers

Faulty Radiographs Long Essays

Question 1. Faulty Radiographs.
Or
Discuss in detail various causes for faulty radiographs and measures to rectify them.
Or
Describe artifacts, blemishes, and faults in dental radiographs.
Answer.

Faulty Radiographs

Faulty Radiographs Short Answers

Question 1. Cone Cut.
Answer.

Cone Cut Causes:

• The cone of the tube did not cover the area of interest
• Improper alignment of PID
• Placement of clip of hanger
• The top of the film is not immersed in the developing solution
• Shape distortion

Cone Cut Correction:

• Place the cone properly
• Position PID properly
• Immerse the film properly in the developer

Question 2. Dark radiograph.
Answer.

Dark radiograph

Question 3. Static Electricity.
Answer.

Static Electricity

These are caused by electrical discharges that produce no visible light but occur on the surface of the emulsion

Static Electricity Causes:

• Rapidly removing the film from the packet
• This may result from visible light produced by sparks caused by a relatively low potential electrical discharge in the air next to the film surface
• The discharge follows a path induced by dust or a roughened intensifying screen

Static Electricity Correction:

• Install an electric humidifier in the darkroom
• Avoid rapid removal of film
• Handle the film carefully
• Coat the intensifying screen with an antistatic solution

Question 4. Film fog.
Answer.

Film fog Causes:

• Light:
  • Light leaks in the darkroom
  • Improper safe light
  • Improper filter in safe light
  • Prolong exposure of the film to the safelight
• Scattered radiation:
  • Scattered, stray, leakage or any other radiation not belonging to the primary beam is undesirable as it produces film fog
  • For intraoral films, filtration, collimation, and film packets that lead to backed sheets should be used to reduce scattered and secondary radiation
  • For intraoral films, grids are used
• Chemical fog:
  • It is produced by prolonged development
  • Development at high temperature
  • Potassium bromide or restrainer prevents chemical fogging in the X-ray film by restraining the action of developing agents on the unexposed silver halide crystals
  • After fixing the radiograph should be thoroughly washed to remove all residual processing chemicals and silver salts from the film surface
  • If the temperature differences between the processing solution and the rinsing water are more than 15º F an orange peel appearance will appearance

Question 5. Tyre track effect.
Answer.

Track Effect Cause:

• The film is reversed while placed in the patient’s mouth
• Thus the tab side of the film faces the beam

Effect:

• The X-rays are partially absorbed by the lead backing
• Tyre track or herringbone pattern is produced on the film
• The film appears light, underexposed and foggy

Track Effect Correction:

• Place the pebbled surface towards the cone

Faulty Radiographs Viva Voce

• Excessive peak kilovoltage leads to insufficient image contrast
• The high temperature of the developer, high concentration of developer, and inadequate fixation lead to dark radiograph

Ideal Radiographs Important Notes

• kVp controls the wavelength and penetration power of X-rays.
• Whenever kVp is increased, X-rays of shorter wavelength and high penetration power are produced. They are called hard X-rays.
• Whenever kVp is decreased, X-rays of longer wavelength and the least penetrating power are produced. They are called soft X-rays.

Ideal Radiographs Long Essays

Question 1. Ideal radiograph.
Answer.

Ideal radiograph Definition:

• An ideal radiograph provides a great deal of information, the image exhibits proper density & contrast, has sharp outlines & is of the same shape & size as the object being radiographed

Ideal radiograph Characteristics:

• Visual characteristics:
  • Density:
    • It is the overall blackness or darkness of a dental radiograph
    • If the density is too dark, the film will appear too dark
    • As a result, images cannot be visualized properly
    • A radiograph with correct density enables the radiographer to view black areas, white areas & gray areas

Factors Affecting The Density:

First Degree Factors:

• Milliampere
  • An increase in milliampere results in increased density of the film
• Exposure time
  • If the exposure time is increased, then film density is increased
• Kilovoltage peak [kVp]
  • If kVp increases, then film density increases
  • Density varies directly to the square of the relative kVp
    D ∝ [kVp]²
• Source film distance
  • Density varies inversely to the square of the source film distance
    Density = [kVp]² x mA x s/[S-F distance]²

Second Degree Factors:

• Subject thickness
  • Density decreases in patients with increased subject thickness
• Developmental conditions
  • Overdevelopment of film leads to dark films
• Type of films
  • High-speed films change the density
• Screens
  • Screens require fewer mAs
• Grids
  • Grids require more mAs
• Amount of filtration used
  • Reduction in the use of filtration increases the density
• Fog
  • Results in darkening of film
  • Contrast:
    • It is the difference in the degree of blackness between adjacent areas on a dental radiograph
    • Dental radiographs with very dark areas & with very light areas are said to have ‘high contrast’
    • Depends On The Following:
      • Quality of film
      • Film processing
      • Subject thickness
      • kVp
      • Exposure time
• Geometric characteristics:
  • Sharpness:
    • It is capable of reproducing even the smallest details of the object on a radiograph

Factors:

• Geometric unsharpness:
  • Size of the focal spot
  • Object film distance
  • Target film distance
• Motion unsharpness
  • Patient
  • Tube
  • Film
• Film unsharpness
  • Grain size
  • Emulsion
  • Film thickness
• Fog unsharpness
• Intensifying screens unsharpness

Read And Learn More: Oral Radiology Question and Answers

• Magnification:
  • It refers to the image that appears larger than the actual size of the object

Factors:

• Target film distance:
  • It is determined by the length of the position indicating device [PID]
  • The longer the PID, the more parallel X-rays, therefore less magnification
• Object film distance
  • Less the object film distance, less the magnification
• Use of intensifying screens
  • It increases the film object distance & thus creates a magnification
• Distortion:
  • It is a variation of the actual size & shape of the object
  • Increasing the vertical angulation leads to the shortening of the image
  • Decreasing the vertical angulation leads to the elongation of the image

• Anatomical accuracy of radiographic image:
  • Labial & lingual CEJ should superimposed
  • Buccal & lingual cusps should superimposed
  • The buccal portion should superimposed over the lingual portion of the alveolar bone
  • No superimposition of zygoma
• Adequate coverage of the anatomic region of interest:
  • Proper alignment of the film must be present
  • The proper film should be selected
  • Proper technique should be selected

Ideal Radiographs Short Essays

Question 1. Density
Answer.

Density

• It is the overall blackness or darkness of a dental radiograph
• If the density is too dark, the film will appear too dark
  • As a result, images cannot be visualized properly
  • A radiograph with correct density enables the radiographer to view black areas, white areas & gray areas

Factors Affecting The Density:

First Degree Factors:

• Milliampere
  • An increase in milliampere results in increased density of the film
• Exposure time
  • If the exposure time is increased, then film density is increased
• Kilovoltage peak [kVp]
  • If kVp increases, then film density increases
  • Density varies directly to the square of the relative kVp
    D ∝ [kVp]²
• Source film distance
  • Density varies inversely to the square of the source film distance
    Density = [kVp]² x mA x s/[S-F distance]²

Second Degree Factors:

• Subject thickness
  • Density decreases in patients with increased subject thickness
• Developmental conditions
  • Overdevelopment of film leads to dark films
• Type of films
  • High-speed films change the density
• Screens
  • Screens require fewer mAs
• Grids
  • Grids require more mAs
• Amount of filtration used
  • Reduction in the use of filtration increases the density
• Fog
  • Results in darkening of film

Question 2. Target film distance.
Answer.

Target film distance

• This is determined in the intraoral machine by the length of the position indicating device [PID]
• The longer the PID, the more parallel X-rays from the middle of the beam strike the object rather than the diverging rays from the periphery of the beam
• Therefore there is less magnification
• The shorter the PID, the fewer parallel X-rays from the middle of the beam strike the object and more of the diverging rays from the periphery of the beam strike the object
• Therefore, there is more magnification

Ideal Radiographs Short Answers

Question 1. Density and Contrast.
Answer.

Density and Contrast

• When contrast is altered, is also changed
• However, when the density is altered by itself, there is no change in contrast
• This is because
  • Change in kVp produces a change in contrast and density
  • Change in mA alone does not change the contrast
• Thus if there is a change in contrast, density also changes
• mA is a prime factor in controlling density, but not a controlling factor for contrast
• Therefore a change in mA will produce a change in density but not in contrast

Question 2. Define ideal radiograph.
Answer.

Ideal radiograph

An ideal radiograph provides a great deal of information, the image exhibits proper density & contrast, has sharp outlines, and is of the same shape & size as the object being radiographed

Question 3. Contrast.
Answer.

Contrast

• It is the difference in the degree of blackness between adjacent areas on a dental radiograph
• Dental radiographs with very dark areas & with very light areas are said to have ‘high contrast’

Depends On the Following:

• Quality of film
• Film processing
• Subject thickness
• kVp
• Exposure time

Ideal Radiographs Viva Voce

• Density is in direct proportion to milliamperage and kilo voltage and is inversely proportional to focal spot [target] film distance
• Exposure time is inversely proportional to milliamperage and kVp. It is directly proportional to the square of the focal spot film distance
• The useful range of density for a dental X-ray is 0.3 – 2. Density increases with an increase in film fog
• Magnification = Target – film distance/Object – film distance

Radiographic Film Processing Long Essays

Question 1. Write about the composition of X-ray film. Describe the mechanism of image formation. Write a note on the composition of developing and fixing solution and their functions.
Answer.

Composition Of Film:

Emulsion:

• It is sensitive to X-rays and visible light
• It records the image
• It consists of:
• Silver halide crystals
• They are composed of mainly silver bromide and lesser content of silver iodide which are photosensitive
  • Each silver grain diameter is 1.8μm
  • Gold may be added to improve its sensitivity
  • Gelatin matrix
  • It suspends silver halide crystals evenly in the gel made from cattle bone
  • It absorbs the processing solution
  • This allows the chemicals to react with silver halide crystals

Base:

• It is made up of Polyethylene terephthalate (polyester)
• Its diameter is 0.18mm
• The function of the base is to support the light-sensitive silver halide crystals
• The base is a slightly blue-tinted to enhance the image quality
• Its translucency cast no patterns on the resultant radiograph
• It withstands exposure during processing without distortion
• It is flexible for proper handling
• Adhesive layer
  • It is applied to the base before the emulsion is applied for proper adaptation

Formation Of Image:

• The film emulsion is made up of silver bromide crystals and silver iodide crystals that are precipitated in gelatin
• When the silver halide crystals are irradiated by X-ray photons it will result in the release of electrons usually by the bromide ions
• This leads to the conversion of bromide ions to bromine atoms by removing electrons
• This recoil electron thus produced has sufficient kinetic energy with which it moves in the crystal and strikes the image site
• This imparts a negative charge to that region
• The free positively charged interstitial silver ions are attracted to the negative latent image site
• This neutralizes the image site with the result that an atom of metallic silver is deposited at the site
• After exposure of a film to radiation, the aggregate of silver atoms at the latent image sites comprises the latent image

Composition Of Developer:

 

Read And Learn More: Oral Radiology Question and Answers

Fixing Solution

Question 2. Write in detail about the processing of X-ray film.
Or
Enumerate various film processing techniques. Describe in detail the manual procession.
Answer.

x-ray film Types:

• Manual method:
  • Time-temperature
  • Visual method
  • Rapid processing method
• Automatic method:
• Monobath method
• Daylight method
• Digitalized processing method
• Self-developing films

Time Temperature Method:

• Initially replenish the developer & fixer solutions
• Set the temperature of the developer
• Unwrap the film
• Hold the film along the sides, & clip it to the hanger
• Agitate the film
• Keep it for the predetermined time
• After that place it in the circulating water
• Agitate for 20 – 30 seconds to remove excess solution
• According to the time & temperature of the developer, set that of the fixer
• Immerse the film in The Fixer
• Agitate for 5 of every 30 seconds
• After it, allow to drain the excess fixer solution
• Place it in circulating water for at least 20 minutes
• Dry the film

Visual Method:

• Place the film in the developer
• View them from time to time
• Look for the degree of darkness in the safelight

x-ray film Advantages:

• Developing to desired darkness is possible
• Fewer chances of errors

x-ray film Disadvantages:

• Individually processing required
• Thus, time-consuming

Automatic Film Processing

• This method uses equipment that automates all the processing steps

Automatic Film Processing Advantages:

• Rapid process
• Uniformity of the results is obtained
• Less space required
• The density and contrast of the film are consistent

Automatic Film Processing Disadvantages:

• Low quality as compared to that processed manually
• High cost of equipment

Automatic Film Processing Mechanism:

• The apparatus consists of a transport mechanism
• This picks up the unwrapped films which are passed through the developer, fixer, and drying sections
• The system uses a series of rollers driven by a constant-speed motor that operates through gears, belts, or chains
• The rollers consist of assemblies of multiple rollers
• It is so designed that the film crosses over from one roller to the next
• The operator may also be able to remove them independently for soaking, cleaning, and repairing

Question 3. Formation of latent image. Add a note about a fixer and developer solution
Answer.

Formation Of Image:

• The film emulsion is made up of silver bromide crystals and silver iodide crystals that are precipitated in gelatin
• When the silver halide crystals are irradiated by X-ray photons it will result in the release of electrons usually by the bromide ions
• This leads to the conversion of bromide ions to bromine atoms by removing an electron
• This recoil electron thus produced has sufficient kinetic energy with which it moves in the crystal and strikes the image site
• This imparts a negative charge to that region
• The free positively charged interstitial silver ions are attracted to the negative latent image site
• This neutralizes the image site with the result that an atom of metallic silver is deposited at the site
• After exposure of a film to radiation, the aggregate of silver atoms at the latent image site comprises the latent image

Fixing Solution:

Composition Of Developer

Radiographic Film Processing Short Essays

Question 1. Developer and fixing solution.
Answer.

Composition Of Developer:

Fixing Solution:

Question 2. Formation of latent image.
Answer.

Formation of the latent image

• The film emulsion is made up of silver bromide crystals and silver iodide crystals that are precipitated in gelatin
• When the silver halide crystals are irradiated by X-ray photons it will result in the release of electrons usually by the bromide ions
• This leads to the conversion of bromide ions to bromine atoms by removing an electron
• This recoil electron thus produced has sufficient kinetic energy with which it moves in the crystal and strikes the image site
• This imparts a negative charge to that region
• The free positively charged interstitial silver ions are attracted to the negative latent image site
• This neutralizes the image site with the result that an atom of metallic silver is deposited at the site
• After exposure of a film to radiation, the aggregate of silver atoms at the latent image site comprises the latent image

Question 3. Film processing.
Answer.

Film Processing Types:

• Manual method:
  • Time-temperature
  • Visual method
  • Rapid processing method
• Automatic method:
• Monobath method
• Daylight method
• Digitalized processing method
• Self-developing films

Time Temperature Method:

• Initially replenish the developer & fixer solutions
• Set the temperature of the developer
• Unwrap the film
• Hold the film along the sides, & clip it to the hanger
• Agitate the film
• Keep it for the predetermined time
• After that place it in the circulating water
• Agitate for 20 – 30 seconds to remove excess solution
• According to the time & temperature of the developer, set that of the fixer
• Immerse the film in The Fixer
• Agitate for 5 of every 30 seconds
• After it, allow to drain the excess fixer solution
• Place it in circulating water for at least 20 minutes
• Dry the film

Film Processing Visual Method:

• Place the film in the developer
• View them from time to time
• Look for the degree of darkness in the safelight

Film processing Advantages:

• Developing to desired darkness is possible
• Fewer chances of errors

Film processing Disadvantages:

• Individually processing required
• Thus, time-consuming

Question 4. Manual film processing.
Answer.

Time Temperature Method:

• Initially replenish the developer & fixer solutions
• Set the temperature of the developer
• Unwrap the film
• Hold the film along the sides, & clip it to the hanger
• Agitate the film
• Keep it for the predetermined time
• After that place it in the circulating water
• Agitate for 20 – 30 seconds to remove excess solution
• According to the time & temperature of the developer, set that of the fixer
• Immerse the film in The Fixer
• Agitate for 5 of every 30 seconds
• After it, allow to drain the excess fixer solution
• Place it in circulating water for at least 20 minutes
• Dry the film

Manual Film Processing Visual Method:

• Place the film in a developer
• View them from time to time
• Look for the degree of darkness in the safelight

Manual Film Processing Advantages:

• Developing to desired darkness is possible
• Fewer chances of errors

Manual Film Processing Disadvantages:

• Individually processing required
• Thus, time-consuming

Question 5. Automatic Film Processing.
Answer.

Automatic Film Processing

• This method uses equipment that automates all the processing steps

Automatic Film Processing Advantages:

• Rapid process
• Uniformity of the results is obtained
• Less space required
• The density and contrast of the film are consistent

Automatic Film Processing Disadvantages:

• Low quality as compared to that processed manually
• High cost of equipment

Automatic Film Processing Mechanism:

• The apparatus consists of a transport mechanism
• This picks up the unwrapped films which are passed through the developer, fixer, and drying sections
• The system uses a series of rollers driven by a constant-speed motor that operates through gears, belts, or chains
• The rollers consist of assemblies of multiple rollers
• It is so designed that the film crosses over from one roller to the next
• The operator may also be able to remove them independently for soaking, cleaning, and repairing

Question 6. Coin test.
Answer.

Coin test AIM:

• To evaluate safelight requirements

Coin test Method:

• Shut all the lights
• Put on the safe light
• Open the film packet
• Place the film over the unwrapped surface
• Place a coin over it
• Leave it for approximately the time required for unwrapping the full-mouth radiograph which is about 5 minutes
• Develop the film

Coin test Result:

• If the image of the coin can be seen on the resultant film, the room is not light-safe

Radiographic Film Processing Short Answers

Question 1. Latent image.
Answer.

Latent image

• When the radiographic film is exposed to the information-carrying beam of photons exiting an object, the photosensitive silver halide crystals in the film emulsion interact with these photons and are chemically changed
• These chemically altered crystals constitute the latent image of the film
• This increases the liability of crystals to the chemical action of the developing process that converts the latent image into a visible image

Question 2. Composition of developer
Answer.

Composition Of Developer:

Question 3. Fixing solution
Answer.

Fixing Solution:

Question 4. Darkroom requirements.
Answer.

Size:

• 3 feet x 3 feet for an individual dentist
• 16 – 20 square feet for group practice
  • Should have sufficient space to accommodate the processing tanks
  • It must include an adequate working area where the films are unwrapped
  • It must contain a storage space
  • It should be well-ventilated
  • Room temperature must be 70 degrees
  • Humidity levels must be between 50-70%
  • The room must include both hot & cold running water
  • Wastebasket for disposal of all film wrappings
  • Safe light mounted on the wall or ceiling
  • It should be at least 4 feet from the work surface

Radiographic Film Processing Viva Voce

• The height of safe light from the working area should be 1.22m [4 feet]
• The temperature of X-ray processing tanks should be between 60-75°F
• In developer, sodium sulfite acts as a preservative
• Hydroquinone in developer is added to increase the contrast of the image

X-Ray Film And Accessories Important Notes

• Half value layer {HVL} characterizes the penetrating quality of x-ray beam.
  • HLV is the thickness of aluminium required to reduce half the number of X-ray photons passing through it.
• Aluminium filter selectively removes the less penetrating photons, which only contributes to patient exposure and doesn’t have enough energy to reach the film.
  • Its thickness is 1.5 mm for 70 kVp.
• Collimator is a radiopaque material (usually lead), which reduces the size of X-ray beam.
  • Thus it reduces patient exposure and increase quality of X-ray film by reducing the formation of scattered radiation and penumbra.
  • X-ray beam is collimated to a circle of 2.75 inches or 7cm.
• IOPA film
  • Size – 0 – 22 x 35 mm – For small children
  • Size – 1 – 24 x 40 mm – For anterior projection
  • Size – 2 – 32 x 41 mm – For adults
• Bitewing film
  • Size – 0 – For very small children
  • Size – 1 – Children
  • Size – 2 – For adults
• Occlusal film
  • 3 times larger than a size 2 film – 57 x 76 mm
• Screen film
  • 8 x 10 inches – for extra oral projection along with the intensifying screen
• Composition of film
  • Emulsion:
    • It is sensitive to X-rays and visible light
    • It records the image
    • It consists of:
      • Silver halide crystals
      • Gelatin matrix
  • Base:
    • It is made up of polyethylene terephthelate (polyester)
  • Adhesive layer:
    • It is applied to base before emulsion is applied for proper adaptation
• Film packet
  • It consists of:
    • An outer plastic wrapping
    • It is made of white paper or soft vinyl
    • It has two sides: label side and tube side
    • The label side has a flap to open the film packet
    • A thin sheet of lead foil
    • It is placed in the plastic wrapper
    • It absorbs most of the X-rays which pass through the film
    • A sheet of black paper
    • It protects the film from any light leak
    • X-ray film
      • It has rounded corners and an embossed raised dot for orientation
• Types of collimator
  • Diaphragm
    • Tubular
    • Rectangular
• Types of filtration
  • Inherent filtration
  • External filtration
• Types of intensifying screens
  • Blue emitting visible light
  • Green emitting visible light
• Composition of intensifying screen
  • Base
    • It is made of polyester plastic with 0.25 mm thickness
  • Reflecting layer
    • It is made up of titanium dioxide coated on the base material and lies below the phosphor layer
  • Protective coat
    • It is made of plastic about 8 mm thickness placed over the phosphor layer to provide protection for the phosphor layer
• Types of grid
  • Stationary grids
    • Parallel grids
    • Focused grids
  • Moving grids
    • Potter bucky grids

Read And Learn More: Oral Radiology Question and Answers

X-Ray Film And Accessories Short Essays

Question 1. Collimation and filtration. Or Collimator
Answer:

Collimation:

• When an X-ray beam is directed at the patient, 90 percent of the X-ray photons are absorbed by the tissues and remaining 10 percent pass through as the information carrying beam results in the formation of image on a film
• Many of the absorbed photons generate scattered radiation that travels in all directions results in film fog which degrades the image contrast
• To reduce a lead collimator in the path of the X-ray beam can be placed
• Collimation means reducing the size of the X-ray beam by placing a radiopaque barrier containing aperture in the path of beam and thus reduces the volume of irradiated tissue by absorbing scattered radiation
• Thus it reduces patient exposure and increases the film quality
• Collimator is the device which collimates the X-ray beam thus reduces the formation of scattered radiation

Collimation Types:

• Diaphragm
• Tubular
• Rectangular

Filtration:

• X-ray beam emitted from the X-ray tube consists of not only high energy but also of low energy photons
• Low-energy photons have little penetrating power
  • They are absorbed within the tissues causing hazards to the patient and give no contribution to image formation
  • The purpose of adopting filtration is to selectively remove these low-energy photons from the X-ray beam by placing an aluminum filter in the path of the beam
  • It also allows high-energy photons to pass through which results in reduced patient exposure

Filtration Types:

• Inherent filtration:
  • This filters the X-ray beam within X-ray machine by glass wall of the X-ray tube, insulating oil that surrounds the X-ray tube and barrier material that prevents the oil escaping out
• External filtration:
  • External filtration is applied in the form of aluminum discs placed in the path of the beam

Question 2. X-Ray Film.
Answer:

X-Ray Film

It is a type of photographic film.

X-Ray Film Types:

• Intraoral films
• Extraoral films

X-Ray Film Composition:

• Emulsion:
  • It is sensitive to X-rays and visible light
  • It records the image
  • It consists of:
    • Silver halide crystals
      • They are composed of mainly silver bromide and lesser content of silver iodide which are photosensitive
      • Each silver grain diameter is 1.8 μm
      • Gold may be added to improve its sensitivity
    • Gelatin matrix
      • It suspends silver halide crystals evenly in the gel made from cattle bone
      • It absorbs the processing solution
      • Thus allows the chemicals to react with silver halide crystals

X-Ray Film Base:

• It is made up of polyethylene terephtlelate (polyester)
• Its diameter is 0.18 mm
• The function of the base is to support the light sensitive silver halide crystals
• Base is slightly blue tint to enhance the image quality
• Its translucency cast no pattern on the resultant radiograph
• It with stands exposure during processing without distortion
• It is flexible for proper handling

X-Ray Film Adhesive layer:

• It is applied to base before emulsion is applied for proper adaptation

X-Ray Film Sizes:

• Periapical radiograhic films:
  • Size 0: small children, 22 x 35 mm
  • Size 1: children, 24 x 40 mm
  • Size 2: adult, 31 x 41 mm
• Occlusal films:
  • Size: 57 x 76 mm

Question 3. Film Packet.
Answer:

Film Packet

• It consists of:
  • An outer plastic wrapping
    • It is made of white paper or soft vinyl
    • It is sealed, semistiff, moisture proof, light proof and clear
    • It should be directed towards the tube
    • It protects the film from exposure to light and saliva
    • It has two sides: label side and tube side
    • The label side has a flap to open the film packet
    • An embossed dot is present for positioning the film
    • The dot must be placed occlusally

• • A thin sheet of lead foil
    • It is placed in the plastic wrapper
    • It absorbs most of the X-rays which pass through the film
    • Thus prevents the soft tissues from it
    • It absorbs the back scattered radiation
    • It prevents fogging
  • A sheet of black paper
    • It protects the film from any light leak
  • X-ray film
    • It has rounded corners and an embossed raised dot for orientation

Question 4. Intensifying Screens.
Answer:

Intensifying Screens

These are image receptors used in combination with the X-ray film for all extraoral radiographic procedures such as panoramic, cephalometric and skull radiography

Intensifying Screens Types:

• Blue emitting visible light
• Green emitting visible light

Intensifying Screens Mechanism:

• Intensifying screens contain various inorganic salts or phosphors would fluoresce when exposed to a X-ray beam
• The intensity of it is directly proportional to intensity of the X-ray beam, which strikes the phosphors crystals
• Each X-ray photon convert into multiple visible light which strikes the X-ray film thus reducing amount of radiation required to expose film
• But it results in loss of fine detail on image because of dispersion of visible lights from phosphor crystals

Intensifying Screens Composition:

• Base:
  • It is made of polyester plastic with 0.25 mm thickness
  • It provides mechanical support for the intensifying screen
• Reflecting layer:
  • It is made up of titanium dioxide coated on the base material and lies below the phosphor layer
  • The main function is to reflect any visible light emitted from the phosphor layer back to the film
  • Devoid of this layer is to get sharpness of the image because this layer produce divergence of the visible light reflected back to the film causing unsharpened image
• Phosphor layer:
  • It is composed of light sensitive phosphor crystals suspended in a plastic material
  • When the phosphors are struck by X-ray photons they emit visible light that exposes the X-ray film
• Protective coat:
  • It is made of plastic about 8 mm thickness placed over the phosphor layer to provide protection for the phosphor layer

Question 5. Grids.
Answer:

Grids

It is a device which consists of an alternative strip of radiopaque and radiolucent material which is placed between the object and the film to improve the quality of the image by removal of scattered radiation that causes fog and reduces film contrast

Composition:

• It is composed of alternate strips of radiopaque that are lead and radiolucent often plastic

Grids Functions:

• When the X-ray photons hit the object secondary photons are generated and they are scattered towards the film
• These scattered photons are deviated in their direction of travel from that of primary beam would cause film fog and reducing the film contrast
• Grids are placed between the object and the film absorbs all scattered radiation that are deviated from the primary beam by radiopaque material and allow only the primary beam through the radiolucent material of plastic into the films

Grids Types:

• Stationary grids:
  • Parallel grids
  • Focused grids
• Moving grids:
  • Potter bucky grids

Question 6. Potter Bucky Grid.
Or
Potter bucky diaphragm.
Answer.

Potter Bucky Grid

• In this the grid is moved sideways across the film during exposure
• This leads to the blurring out of the shadows of grid strips
• Thus they are not visible on the film
• The image of the radiopaque grid lines on the film can be deleted by mechanically moving the grid in the direction of 90 degree to the grid lines during exposure
• This results in blurring out of radiolucent lines
• Results in uniform exposure
• It does not interfere with the absorption of scattered radiation

Question 7. Filtration.
Answer.

Filtration

• X-ray beam emitted from the X-ray tube consists of not only high energy but also of low energy photons
• Low energy photons have little penetrating power
  • They are absorbed within the tissues causing hazards to the patient and gives no contribution to image formation
  • The purpose of adopting filtration is to selectively remove these low energy photons from the X-ray beam by placing an aluminium filter in the path of the beam
  • It also allows high energy photons to pass through which results in reduced patient exposure

Filtration Types:

• Inherent filtration:
  • This filters the X-ray beam within X-ray machine by glass wall of the X-ray tube, insultating oil that surrounds the X-ray tube and barrier material that prevents the oil escaping out
• External filtration:
  • External filtration is applied in the form of aluminium discs placed in the path of the beam.

X-Ray Film And Accessories Short Answers

Question 1. Composition of X-Ray Film.
Answer:

Composition of X-Ray Film

It is a type of photographic film.

X-Ray Film Types:

• Intraoral films
• Extraoral films

X-Ray Film Composition:

Emulsion:

• It is sensitive to X-rays and visible light
• It records the image
• It consists of:
  • Silver halide crystals
    • They are composed of mainly silver bromide and lesser content of silver iodide which are photosensitive
    • Each silver grain diameter is 1.8 μm
    • Gold may be added to improve its sensitivity
  • Gelatin matrix
    • It suspends silver halide crystals evenly in the gel made from cattle bone
    • It absorbs the processing solution
    • Thus allows the chemicals to react with silver halide crystals

X-Ray Film Base:

• It is made up of polyethylene terephtlelate (polyester)
• Its diameter is 0.18 mm
• The function of the base is to support the light sensitive silver halide crystals
• Base is slightly blue tint to enhance the image quality
• Its translucency cast no pattern on the resultant radiograph
• It with stands exposure during processing without distortion
• It is flexible for proper handling

X-Ray Film Adhesive layer:

• It is applied to base before emulsion is applied for proper adaptation

Film Sizes:

• Periapical radiographic films:
  • Size 0: small children, 22 x 35 mm
  • Size 1: children, 24 x 40 mm
  • Size 2: adult, 31 x 41 mm
• Occlusal films:
  • Size: 57 x 76 mm

Question 2. Composition of Intensifying Screens.
Answer:

Composition:

Base:

• It is made of polyester plastic with 0.25 mm thickness
• It provides mechanical support for the intensifying screen

Reflecting layer:

• It is made up of titanium dioxide coated on the base material and lies below the phosphor layer
• The main function is to reflect any visible light emitted from the phosphor layer back to the film
• Devoid of this layer is to get sharpness of the image because this layer produce divergence of the visible light reflected back to the film causing unsharpened image

Phosphor layer:

• It is composed of light sensitive phosphor crystals suspended in a plastic material
• When the phosphors are struck by X-ray photons they emit visible light that exposes the X-ray film

Protective coat:

• It is made of plastic about 8 mm thickness placed over the phosphor layer to provide protection for the phosphor layer

Question 3. Collimation
Answer:

Collimation

• When an X-ray beam is directed at the patient, 90 percent of the X-ray photons are absorbed by the tissues and remaining 10 percent pass through as the information carrying beam results in the formation of image on a film
• Many of the absorbed photons generate scattered radiation that travels in all directions results in film fog which degrades the image contrast
• To reduce a lead collimator in the path of the X-ray beam can be placed
• Collimation means reducing the size of the X-ray beam by placing a radiopaque barrier containing aperture in the path of beam and thus reduces the volume of irradiated tissue by absorbing scattered radiation
• Thus it reduces patient exposure and increases the film quality
• Collimator is the device which collimates the X-ray beam thus reduces the formation of scattered radiation

Types:

• Diaphragm
• Tubular
• Rectangular

Viva Voce

• For a given beam the intensity is inversely proportional to the square of the distance from the source
• Base of x-ray film is composed of polyester polyethylene teraphalate
• Emulsion of x-ray film consists of gelatin and silver halide
• Intensifying screen is composed of base, titanium oxide, phosphor and protective coat
• Potty Bucky diaphragm absorbs scattered radiation

Radiation Biology Important Notes

• The action of radiation can be direct or indirect
  • Direct effect occurs when the energy of a photon is transferred directly to biological molecules.
  • The indirect effect occurs when a photon is absorbed by water and from free radicals which in turn reacts with biological macromolecules.
  • About two-thirds of radiation-induced biological damage results from indirect effects.
• The order of tissue susceptibility affected by radiation are:
  • Spermatozoa and oogonia (most susceptible)
  • Bone marrow with immature cells including lymphocytes
  • Intestinal mucosa
  • Epithelium of skin
  • Muscle cells
  • Nerves
• For osteoradionecrosis to occur, three factors should be present. They are:
  • Radiation at the site
  • Injury at the site and
  • Infection at the site
• Susceptibility of different tissues to radiation-induced cancer

• Linear Energy Transfer (LET): The rate of loss of energy from a particle as it moves through the irradiated material is called LET.
  • The dose required to produce a certain biological effect is reduced as the Linear Energy Transfer (LET) of the radiation is increased.
• The amount of radiation necessary to produce a noticeable skin reaction is called an Erythema dose.
  • The skin erythema dose is 300 – 400R.

Radiation Biology Long Essays

Question 1. Enumerate hazards of radiation. Discuss the effects of radiation on oral tissues.
Or
What is ionizing radiation? Describe the biological effects of excessive radiation on orofacial tissues.
Or
What are the effects of radiation in the oral cavity? Write in detail about osteo-radionecrosis.
Or
Describe in detail the effects of radiation on the oral cavity.
Answer.

Ionizing Radiation:

• It is defined as radiation that is capable of producing ions by removing or adding electrons to an atom

Hazards Of Radiation:

• Biologic changes
  • Changes in DNA:
    • Change in base
    • Disruption of hydrogen bonds
    • Breakage of DNA strands
    • Cross-linking of DNA strands
  • Proteins:
    • Denaturation of proteins
• Cellular changes:
  • Nuclear changes
  • Chromosome aberration
  • Cytoplasmic changes
• Tissue changes:
  • Non stochastic Effects
  • Stochastic Effects

Radiation Effects On Oral Tissues:

• Oral Mucous Membrance:
  • Mucositis
  • Desquamation of epithelial layer
  • Infection of the oral cavity
  • Candidiasis
  • Atrophic mucosa
  • Ulceration
  • Radiation necrosis

Read And Learn More: Oral Radiology Question and Answers

• Taste buds:
  • Degeneration
  • Loss of taste sensation
• Salivary glands:
  • Xerostomia
  • Loss of salivary secretion
  • Difficult & painful swallowing
  • Decreased buffering capacity
  • Susceptibility to radiation caries
• Teeth:
  • Retards growth of teeth
  • Inhibit cellular differentiation
  • Premature eruption
  • Retard root formation
  • Fibroatrophy of pulp

Radiation Caries:

Pathogenesis:

Types:

• • Superficial
  • Involving cervical region
  • Dark pigmentation
• Bone:
  • Osteoradionecrosis
  • Hypocellularity
  • Hypoxia
  • Hypovascularity

Osteoradionecrosis:

• It is a radiation-induced pathologic process characterized by chronic and painful infection and necrosis is accompanied by late sequestration and sometimes permanent deformity.
• This is one of the most serious complications of radiation to the head and neck seen frequently

Factors Leading To Osteoradionecrosis:

• Irradiation of an area of previous surgery before adequate healing has taken place
• Irradiation of lesion near the bone
• Poor oral hygiene and continued use of irritants
• Poor patient cooperation in managing irradiated tissue
• Surgery in the irradiated area
• Failure to prevent trauma to the irradiated area

Clinical Features:

• Nonhealing dead bone
• The bone becomes hypovascular, hypocellular, and hypomineralized
• Mandible is more effected than maxilla

Treatment:

• Debridement of necrotic tissue should be done along with the removal of the sequestrum
• Administration of intravenous antibiotics and hyperbaric oxygen therapy
• Maintenance of oral hygiene is necessary

Radiation Biology Short Essays

Question 1. Osteoradionecrosis
Answer.

Osteoradionecrosis

• It is a radiation-induced pathologic process characterized by chronic and painful infection and necrosis is accompanied by late sequestration and sometimes permanent deformity.
• This is one of the most serious complications of radiation to the head and neck seen frequently

Factors Leading To Osteoradionecrosis

• Irradiation of an area of previous surgery before adequate healing has taken place
• Irradiation of lesion near the bone
• Poor oral hygiene and continued use of irritants
• Poor patient cooperation in managing irradiated tissue
• Surgery in the irradiated area
• Failure to prevent trauma to the irradiated area

Osteoradionecrosis Clinical Features:

• Nonhealing dead bone
• The bone becomes hypovascular, hypocellular, and hypomineralized
• Mandible is more effected than maxilla

Osteoradionecrosis Treatment:

• Debridement of necrotic tissue should be done along with the removal of the sequestrum
• Administration of intravenous antibiotics and hyperbaric oxygen therapy
• Maintenance of oral hygiene is necessary

Question 2. Effects of radiation
Or
Hazards of radiation.
Answer.

Effects of radiation

• Biological effects:
  • Nucleic acids
    • X-ray damages the DNA molecules causing cellular death by the following changes
    • Change in the base
    • Disruption of H+ bond
    • Breakage of DNA strand
    • Crosslinking of the DNA Strands
  • Proteins
    • Causes
    • Breakage of hydrogen bonds
    • Denaturation of proteins
    • Crosslinking
• Cellular effects:

• • Effects at tissue and organ level
    • Non – stochastic effects
      • It has specific damaging effects on the body of the person exposed to the high dose of radiation
      • Ex: reddening of skin, cataract
    • Stochastic effects
      • It refers to the radiation that may/may not affect the person
  • Short term effects
    • It depends on the radiosensitivity of cells
    • More injury occurs to the proliferating tissues
    • Ex: bone marrow
    • While less proliferating cells have no sign of injury
    • Ex: muscles
  • Long term effects
    • Depends on the radiosensitivity of cells
    • Proliferating tissues are more affected compared to that of less proliferating tissues
    • Example: more injury occurs to bone marrow as compared to that of muscles

Question 3. Effects of radiation on oral tissues.
Answer.

• Oral Mucous Membrance
  • Mucositis
  • Desquamation of epithelial layer
  • Infection of the oral cavity
  • Candidiasis
  • Atrophic mucosa
  • Ulceration
  • Radiation necrosis
• Taste buds:
  • Degeneration
  • Loss of taste sensation
• Salivary glands:
  • Xerostomia
  • Loss of salivary secretion
  • Difficult & painful swallowing
  • Decreased buffering capacity
  • Susceptibility to radiation caries
• Teeth:
  • Retards growth of teeth
  • Inhibit cellular differentiation
  • Premature eruption
  • Retard root formation
  • Fibroatrophy of pulp

Types:

• • Superficial
  • Involving cervical region
  • Dark pigmentation
• Bone:
  • Osteoradionecrosis
  • Hypocellularity
  • Hypoxia
  • Hypovascularity

Question 4. Radiotherapy
Answer.

Radiotherapy

• It is the treatment of the disease using ionizing radiation

Principle:

• Rapidly proliferating cells are more sensitive to ionizing as compared to normal cells

Advantages:

• No function loss
• Cosmetic
• Protect adjacent uninvolved area
• Possible to treat in inaccessible areas

Disadvantages:

• Development of secondary tumours
• Mucositis
• Dysguea
• Xerostomia

Types Of Therapy:

• Curative
  • It permanently eradicates the disease
• Palliative
  • It leads to a temporary improvement in the patient’s condition

Types Of Radiation:

• External radiation
• Internal radiation
• Brachytherapy

Question 5. Radiation hazards of jaws.
Answer.

Radiation hazards of jaws

• The marrow is replaced by fatty marrow and fibrous connective tissue
• The endosteum becomes atrophic
• The bone becomes hypovascular, hypocellular, and hypomineralized
• The complication following irradiation i.e. “Osteoradionecrosis”
• Necrosis of bone may result in nonhealing ulcers which may occur after tooth extraction
• Lack of osteoblastic and osteoclastic activity in endosteum
• Mandible is more commonly affected than maxilla
• On the radiograph, osteoradionecrosis does not show any periosteal reaction as that seen in the case of osteomyelitis

Radiation Biology Short Answers

Question 1. Effects of radiation on developing tooth.
Answer.

Effects of radiation on developing tooth

Question 2. Radiation mucositis.
Answer.

Radiation mucositis

• The oral mucous membrane contains the basal layer of differentiating intermitotic cells which are highly radiosensitive at the end of the second week of therapy the mucous membrane begins to show areas of redness and inflammation, this state is called “Mucositis”
• As the therapy continues the mucous membrane breaks down with the formation of white or yellow pseudo-membrane
• At the end of the therapy, the mucositis is severe, leading to difficulty in talking, eating, and swallowing
• After termination of therapy, the healing may be complete after about two months, but the mucous membrane tends to become thin, atrophic, and relatively avascular
• Secondary infection by candida albicans is a prevalent complication
• The patient is usually prone to oral ulcerations and unable to tolerate dentures

Question 3. Types of radiation caries.
Answer.

Types of radiation caries

• Primarily involving cementum and dentin in the cervical areas
  • This lesion progresses around the teeth circumference and ultimately results in amputation of the crown
• Generalized superficial lesions attacking the Buccal, occlusal, incisal, and palatal surfaces of the teeth
• Dark pigmentation of the crown

Question 4. Acute radiation syndrome.
Answer.

Acute radiation syndrome

Collective signs and symptoms occurring after whole-body radiation exposure

Question 5. Units of radiation
Answer.

Units of radiation

• Exposure:
  • It refers to the measurement of ionization in air produced by X-rays
  • The unit of exposure is roentgen [R]
  • One roentgen is the quantity of gamma radiation that produces an electrical charge of 2.58 x 10^-4coulombs in a kilogram of air at standard temperature and pressure
  • It is also defined as the amount of gamma radiation that will be produced in 1 cc of air
  • It is used to measure the intensity of radiation to which an object is exposed
    1R = 2.58 x 10^-4 C/kg
    1C/kg = 3.88 x 10³ R
• Absorbed dose:
  • It is the amount of energy absorbed by a tissue
  • Radiation absorbed dose or rad is the unit of dose
  • It is equal to the deposition of 100 ergs of energy per gram of tissue
  • In the SI system, the unit of measurement of dose is Gray (GY)
    1Gy = 1 joule/kg or 100 rads
    1 rad = 100 ergs/g of absorber
• Dose equivalent:
  • It is used to compare the biological effects of different types of radiation
  • Its unit is roentgen equivalent – man, rem
  • In the SI system, the unit of dose-equivalent is the Sievert {Sv}
    1 rem = 0.01 Sv
• Quality factor:
  • It refers to its biological effect relative to standard exposure to X-ray
• Relative biological effectiveness:
  • It is similar to the quality factor
• Radioactivity:
  • It refers to the decay rate of a sample of radioactive material
  • Its traditional unit of radioactivity is curie [Ci]
  • SI unit is Becquerel [Bq]
    1 mCi = 37 mega Bq
    1 Bq = 2.7 x 10^-11 Ci

Radiation Biology Viva Voce

• The unit of measurement of radiation exposed to the patients during dental X-ray procedures is Roentgen
• SI unit of measuring radioactivity is BecquerelThe most radio-susceptible organ for radiation cancer is the stomach
• The tissue most susceptible to radiation is blood-forming cells
• The most sensitive period in humans for inducing developmental abnormalities is during the period of organogenesis (18 – 45 days of gestation)
• The sensitive sites within the nucleus are DNA and chromosomes
• The order of the cell cycle is G1 S G2 M
• If the radiation exposure occurs after DNA synthesis [i.e. in G2 or late S], only one arm of the affected chromo will be broken.
• If the radiation exposure occurs before DNA replication [i.e. in G1 or early S], the damage occurs in both arms.
• The most sensitive phase to radiation is the G2 phase while the least sensitive phase is the ‘S’ phase
• The mean exposure to radiation from one IOPA is 300 mR
• Mean exposure from dental X-ray can be reduced to as low as 1 – 10 mR by using improved techniques
• The mean exposure of radiation to gonads from one IOPA is 1/1000 x 300 mR = 0.03 mR
• In the treatment of oral cancers, the fraction of the total dose given in each appointment is in the range of 150 rads.

Radiation Protection Important Notes:

• Lead aprons and collars
  Advantages:
  • Lead aprons reduce 94% if scattered radiation to the gonads
  • Protects gonads from radiation exposure
  • Thyroid collars reduce the exposure of this gland by 92%
• Position distance rule
  • The operator should stand at least 6 feet from the patient, at an angle of 90 degrees to 135 degrees to the central ray beam when the exposure is made.
  • This called as Position – – distance rule.
• E speed films
  Advantages:
  • The most effective method of reducing patient dose
  • The risk is reduced by a factor of 2
  • Contains large tubular grains which increase the speed
  • The exposure time is 0.2 sec compared to regular film which is 9 sec
  • Disadvantage
  • Decreases image sharpness.

Radiation Protection Long Essays

Question 1. Enumerate hazards of radiation. Describe protective measures for the patient and the operator against it.
Answer.

Hazards Of Radiation:

• Biologic changes:
  • Changes in DNA:
    • Change in base
    • Disruption of hydrogen bonds
    • Breakage of DNA strands
    • Cross-linking of DNA strands
  • Proteins:
    • Denaturation of proteins
• Cellular changes
  • Nuclear changes
  • Chromosome aberration
  • Cytoplasmic changes
• Tissue changes:
  • Non stochastic Effects
  • Stochastic Effects

Radiation Protection:

• Radiation protection for the patient:
  • Patient selection:
    • Professional judgment should be used to select the patient for an X-ray examination
  • Choice of equipment:
    • Image receptor – to reduce the exposure time
    • A focal spot to film distance
    • With the increase in distance, the exposure time reduces
    • Collimation – it reduces the size of the X-ray beam
    • Filtration – to remove low-energy photons
    • Use of lead aprons and collars
    • It minimizes unnecessary radiation exposure
  • Choice of intraoral technique:
    • Parallel radiographic technique causes less exposure, hence used
  • X-ray equipment:
    • Make use of:
    • High kVp
    • Increased made
    • Reduced exposure time

Read And Learn More: Oral Radiology Question and Answers

• • Processing of film:
    • Make use of the proper method of processing
    • Avoid repetition of X-ray
  • Interpretation of image:
    • Properly interpreted the X-ray in a semi-darkened room
    • Note down all the necessary details
• Radiation protection to the operator:
  • The following measures must be carried out by the operator to avoid unnecessary radiation exposure
  • During exposure, the operator must leave the room/stand behind a suitable barrier
  • The operating room should meet the minimum shielding requirements
  • The position of the operator during exposure should be 6 feet away from the source
  • At an angle of 90 – 135°
  • Avoid holding the film intraorally
  • Avoid stabilizing the tube during exposure
  • Use a lead apron in the absence of a barrier
  • Avoid the use of fluorescence mirror during exposure
  • Make use of filtration
  • Carry out personal radiation monitoring periodically

Question 2. Discuss various measures for radiation protection.
Answer.

• Radiation protection for the patient:
  • Patient selection:
    • Professional judgment should be used to select the patient for an X-ray examination
  • Choice of equipment:
    • Image receptor – to reduce the exposure time
    • A focal spot to film distance
    • With the increase in distance, the exposure time reduces
    • Collimation – it reduces the size of the X-ray beam
    • Filtration – to remove low-energy photons
    • Use of lead aprons and collars
    • It minimizes unnecessary radiation exposure
  • Choice of intraoral technique:
    • Parallel radiographic technique causes less exposure, hence used
  • X-ray equipment:
    • Make use of:
      • High kVp
    • Increased mA
    • Reduced exposure time
  • Processing of film:
    • Make use of the proper method of processing
    • Avoid repetition of X-ray
  • Interpretation of image:
    • Properly interpret the X-ray in a semi-darkened room
    • Note down all the necessary details
• Radiation protection to the operator:
  • The following measures must be carried out by the operator to avoid unnecessary radiation exposure
  • During exposure, operator must leave the room/stand behind a suitable barrier
  • The operating room should meet the minimum shielding requirements
  • The position of the operator during exposure should be 6 feet away from the source
  • At an angle of 90 – 135°
  • Avoid holding the film intraorally
  • Avoid stabilizing the tube during exposure
  • Use a lead apron in the absence of a barrier
  • Avoid the use of fluorescence mirror during exposure
  • Make use of filtration
  • Carry out personal radiation monitoring periodically
• Radiation protection to the public:
  • X-ray room must be
  • Lined with lead
  • Constructed with gypsum
  • Painted with barium

Radiation Protection Short Essays

Question 1. Radiation protection for patients.
Answer.

• Patient selection:
  • Professiojudgmentment should be used to select the patient for an X-ray examination
• Choice of equipment:
  • Image receptor – to reduce the exposure time
  • A focal spot to film distance
  • With the increase in distance, the exposure time reduces
  • Collimation – it reduces the size of the X-ray beam
  • Filtration – to remove low-energy photons
  • Use of lead aprons and collars
  • It minimizes unnecessary radiation exposure
• Choice of intraoral technique:
  • Parallel radiographic technique causes less exposure, hence used
• X-ray equipment:
  • Make use of:
  • High kVp
  • Increased made
  • Reduced exposure time
• Processing of film:
  • Make use of the proper method of processing
  • Avoid repetition of X-ray
• Interpretation of image:
  • Properly interpret the X-ray in a semi-darkened room
    Note down all the necessary details

Question 2. Radiation protection for the operator.
Answer.

Radiation protection for the operator

• The following measures must be carried out by the operator to avoid unnecessary radiation exposure
• During exposure, the operator must leave the room/stand behind a suitable barrier
• The operating room should meet the minimum shielding requirements
• The position of the operator during exposure should be 6 feet away from the source
• At an angle of 90 – 135°
• Avoid holding the film intraorally
• Avoid stabilizing the tube during exposure
• Use a lead apron in the absence of a barrier
• Avoid the use of fluorescence mirror during exposure
• Make use of filtration
• Carry out personal radiation monitoring periodically

Question 3. Image receptors.
Answer.

• E-speed films:
  • Used to reduce the exposure time
• Double-sided emulsion:
  • Reduces exposure
• Double film packets:
  • Reduces the radiation needed
• Xeroradiography
  • Good edge enhancement
  • Good image quality
  • Reduces exposure
• Intensifying screens:
  • Used in extraoral radiography
  • Contains phosphors that fluorescence on exposure to the x-ray beam
  • The intensity of it is directly proportional to the intensity of the x-ray beam

Question 4. Intensifying Screens.
Answer.

Intensifying Screens

These are used with all extraoral radiographs

Intensifying Screens Types:

• Blue emitting
• Green emitting

Intensifying Screens Mechanism:

Intensifying Screens Composition:

• Base
• Reflecting layer
• Phosphor layer
• Protective coat

Radiation Protection Short Answers

Question 1. ALARA principle.
Answer.

ALARA principle

• It is the abbreviation of “As Low As Reasonably Achievable”
• It suggests that no matter how small the dose is, the stochastic effect may result.
• Following are the guidelines of the ALARA principle
• For radiation workers
• For occupational exposure – 50 mSv in 1 year
• For reproductive age – 10 mSv in 1 year
• For general public
• Annual effective dose – 1 mSv

Question 2. Dosimetry
Answer.

Dosimetry

• It is the measurement of the quantity of the radiation exposure or the amount of the energy absorbed per unit mass at an interest site

Dosimetry Techniques:

• Ionization chamber:
  • Plates with opposite charges are connected to an electrometer
  • These are separated by a standard volume of air
  • The X-ray beam is passed through the air
  • This leads to the generation of positive and negative ions
  • These are attracted to the plates
  • The potential difference between the plates is measured
• Film badges:
  • A worn film with metallic badges is used
  • It is processed along with the films of known amount of exposure
  • Next, the degree of darkening is measured and compared
• Thermoluminescent dosimeters:
  • Crystals like lithium fluoride are used
• These crystals absorb radiation energy:
  • It results in the release of visible light
  • This is proportional to the absorbed energy

Question 3. Leakage radiation/Stray radiation.
Answer.

Leakage radiation/Stray radiation

• It is defined as radiation emitted by any other part of the X-ray tube other than the focal spot
• It can be prevented by
• Avoid holding of the tube during exposure
• Check the X-ray machine periodically for leakage

Question 4. Thermoluminescence dosimeter.
Answer.

Thermoluminescence dosimeter

• Crystals like lithium fluoride are used
• These crystals absorb radiation energy
• It results in the release of visible light
• This is proportional to the absorbed energy

Question 5. Position & distance rule.
Answer.

Position & distance rule

• The operator should stand at least 6 feet from the patient, at an angle of 90 – 135° to the central ray beam when the exposure is made.
• This is called the position and distance rule.

Radiation Protection Viva Voce

• The gonadal dose is 1/1000 of exposure to skin
• Dosimetry – Determining the quantity of radiation exposure or does.
• The distance of the safe light from the working area in a dark room is 4 feet