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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

X-ray film and accessories notes

• 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

Radiographic film and accessories short notes

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

X-ray film types and components

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

X-ray film and accessories in radiology

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.

Dental X-ray film and accessories notes

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

X-ray cassettes and screens short essay

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

Radiographic film and intensifying screen essay

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

X-ray film construction and types

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

Biological effects of radiation long essay

• 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.

Read And Learn More: Oral Radiology Question and Answers

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

• 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:

Essay on biological effects of ionizing radiation

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

Biological effects of radiation short essay

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

Short and long notes on biological effects of radiation

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

Cellular effects of 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-induced biological damage essay

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.

Essay on radiation protection in radiology

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

Read And Learn More: Oral Radiology Question and Answers

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

• • 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 safety measures long and short notes

• 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 in dentistry essay

• 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

Principles of radiation protection essay

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

Radiation protection in medical imaging

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

Personal protective equipment in radiology essay

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

Radiation protection methods in diagnostic radiology

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

Production Of Ray

Important Notes

• The X-ray machine has an X-ray tube, which consists of
  • Cathode, which serves as a source of electrons.
  • Anode (target) at which beam of high-speed electrons are directed
• The cathode has filaments and a focusing cup.
  • Filaments are coils of Tungsten, which is the source of electrons within the X-ray tubes.
  • The Molybdenum Focusing Cup focused the electrons within the X-ray tubes.
• The anode is composed of a Tungsten Target and Copper Steam.
  • The target serves the purpose of converting the kinetic energy of electrons emitted from the cathode source into X-ray photons.
  • Tungsten is selected because of its properties such as high atomic number, high melting point, and low vapor pressure.
  • Copper Stem dissipates heat thereby reducing the risk of target melting.

Production of X-ray long essay

Production Of Ray Long Essays

Question 1. What are the parts of an X-ray tube? Describe the working of the X-ray tube and add a note on Bremmstrahlung radiation.
Answer.

Apparatus:

• Cathode:
  • Filaments
  • Focussing cup
• Anode
  • Tungsten target
  • Copper stem
• Glass tube:
  • It encloses the above apparatus
  • Cathode:
    • Filaments
      • Made up of tungsten wire
      • It is connected to an electric current
      • On passage of electric current through this filament, it gets heated and emits electrons
      • A milliampere current controls the number of electrons
    • Focussing cup
      • It is made up of molybdenum
      • It is a concave reflector cup
      • The electrons emitted from the filament are received by it
      • These electrons are then focused toward the focal spot, which is the anode
  • Anode:
    •  Tungsten target
      • This converts the kinetic energy of electrons into X-ray photons
    • Copper stem
      • It is a good thermal conductor

Electric current → heats the filament → Electrons are emitted from it → Electrons get collected towards the focusing cup → this focusing cup reflects the electrons to the tungsten target → this tungsten target converts electrons to X-ray photons

Production of X-ray short note

Bremmstrahlung Radiation:

• These are produced due to high-speed electrons
• These electrons pass just near the nucleus
• These are attracted by the positively charged nucleus
• This leads to the loss of some of its kinetic energy
• Further results in deflected and decelerated electrons and low-energy photons

Read And Learn More: Oral Radiology Question and Answers

When an electron comes close to the nucleus of a tungsten atom and is slowed down, an X-ray photo of lower energy, known as general radiation, results

An electron that dislodges an inner shell electron from the tungsten atom results in the rearrangement of the remaining orbiting electrons and the production of an X-ray photon known as characteristic radiation

Production of Ray Short Essays

Question 1. X-ray machine/Working of X-ray tube.
Answer.

Apparatus:

• Cathode:
  • Filaments
  • Focussing cup
• Anode
  • Tungsten target
  • Copper stem
• Glass tube:
  • It encloses the above apparatus
  • Cathode:
    • Filaments
      • Made up of tungsten wire
      • It is connected to an electric current
      • On passage of electric current through this filament, it gets heated and emits electrons
      • A milliampere current controls the number of electrons
    • Focussing cup
      • It is made up of molybdenum
      • It is a concave reflector cup
      • The electrons emitted from the filament are received by it
      • These electrons are then focused toward the focal spot, which is the anode
  • Anode:
    • Tungsten target
      • This converts the kinetic energy of electrons into X-ray photons
    • Copper stem
      • It is a good thermal conductor

X-ray production process essay

Electric current → heats the filament → Electrons are emitted from it → Electrons get collected towards the focusing cup → this focusing cup reflects the electrons to the tungsten target → this tungsten target converts electrons to X-ray photons

Question 2. Position indicating device [PID].
Answer.

Position indicating device [PID]

It is an open-ended lead cylinder that extends from the opening of the metal housing of the tube head, also called the “cone.”

It appears as an extension of the tube head

Position Indicating Device Types:

• Conical
• Rectangular
• Round

Position Indicating Device Significance:

• Long PID results in a less divergent X-ray beam
• This minimizes the irradiation of tissues
• Causes an increase in target film distance
• This further improves the quality of the image

X-ray generation long and short answer questions

Question 3. Production of X-ray
Answer.

Production of X-ray

• Potential differences develop between the cathode and the anode
• This results in the emission of electrons from the tungsten filament
• The emitted electrons are stopped suddenly at the focal spot
• This sudden stoppage causes the conversion of electrons into X-ray photons
• The heat generated during the process is absorbed by the oil circulated in the glass of the X-ray tube

Production of X-ray Mechanism:

• Bremmstrahlung Radiation:
  • These are produced due to high-speed electrons
  • These electrons pass just near the nucleus
  • These are attracted by the positively charged nucleus
  • This leads to the loss of some of its kinetic energy
  • Further results in deflected and decelerated electrons and low-energy photons
• Characteristic radiation:
  • The high-energy electrons hit the target atom
  • Electrons are ejected from the inner orbit
  • This leads to a vacancy that is filled with electrons from the outer orbit

This results in the emission of a photon whose energy is equivalent to the difference in the energy levels of two orbits

When an electron comes close to the nucleus of a tungsten atom and is slowed down, an X-ray photo of lower energy, known as general radiation, results

An electron that dislodges an inner shell electron from the tungsten atom results in the rearrangement of the remaining orbiting electrons and the production of an X-ray photon known as characteristic radiation

X-ray tube working principle essay

Production Of Ray Short Answers

Question 1. Bremmstrahlung radiation.
Answer.

Bremmstrahlung radiation

• These are produced due to high-speed electrons
• These electrons pass just near the nucleus
• These are attracted by the positively charged nucleus
• This leads to the loss of some of its kinetic energy
• Further results in deflected and decelerated electrons and low-energy photons

When an electron comes close to the nucleus of a tungsten atom and is slowed down, an X-ray photo of lower energy, known as general radiatio,n results

An electron that dislodges an inner shell electron from the tungsten atom results in the rearrangement of the remaining orbiting electrons and the production of an X-ray photon known as characteristic radiation

Question 2. Characteristic radiation.
Answer.

Characteristic radiation

• The high-energy electrons hit the target atom
• Electrons are ejected from the inner orbit
• This leads to a vacancy that is filled with electrons from the outer orbit

This results in the emission of a photon whose energy is equivalent to the difference in the energy levels of two orbits

X-ray tube with a rotating anode, which allows the head at the focal spot to spread out across a large surface area

Question 3. Focal spot.
Answer.

Focal spot

• The area of the target at which the electrons are absorbed and X-rays are generated is called the focal spot
• The size and shape of the focal spot are determined by the size and shape of the electron stream when it hits the anode

Focal spot Types:

• Actual focal spot
  • It is the area on the anode that is struck by the electrons
• Effective focal spot
  • It is the length and width of the emitted X-ray beam as projected down the central axis of the X-ray tube

Production of X-ray physics essay

Production Of X-Ray Viva Voce

• The cathode of the X-ray tube is made up of tungsten
• Anode is made up of tungsten embedded in a copper stem
• The target is kept at an angle of 20°
• Radiations produced from focal spots are primary radiations
• Radiations that are reflected from objects are secondary
• Factors necessary for the production of X-rays are a source of electrons, an accelerator, and a target
• 0.2 – 0.8% of cathode rays are transformed into X-rays after striking the anode target.
• The average wavelengths of X-rays used in dentistry is 0.6 – 1 A.U.
• X-rays

Production of X-rays in radiology exam questions

Properties Of X-Ray

Important Notes

• Properties of X-rays
  • Travel at the rate of speed of light
  • Invisible
  • Cannot be focused, reflected or reflected
  • Effected by magnetic and electrical fields
  • They effect photographic plates
  • They cast shadows of the object in their paths
• The three mechanisms that explains the interactions of X-rays with matter are
  • Coherent scattering
  • Photoelectrical absorption
  • Compton scattering
• Thomson Effect/Classical Scattering/Coherent Scattering
  • It occurs when a low – energy incident photon passes near an outer electron of an atom
  • The incident photon is non absorbed but scattered without loss of energy.
  • Energy of scattered photon = Energy of incident photon
  • It accounts for about 8% of the total number of interactions
• Photoelectric Absorption.
  • It occurs when an incident photon collides with a bound electron in an atom.
  • The incident photon is absorbed and the electron is expelled from its shell and becomes a photoelectron
  • Energy of photoelectron = Energy of incident photon – blinding energy of electron.
  • It accounts for about 30% of interactions.
• Compton Scattering.
  • It occurs when a photon interacts with an outer electron of an atom.
  • The electron receives kinetic energy and recoils from the point of impact.
  • The incident photon is scattered from the site of collision, making the atom ionized.
  • Approximately 62% of photon undergo Compton scattering.
  • Compton scattering is the major source of secondary radiation.
• Inverse square law.
  • It states that the intensity of the X-ray beam is inversely proportional to the square of the distance from the source to the film
  • Increased distance leads to the divergence of the X-ray beam

Properties of X-rays in radiology

Properties Of X-Ray Short Essays:

Question 1. Properties of X-ray.
Answer.

Properties of X-ray

• Physical Properties:
  • It is electromagnetic radiation
  • It travel through space
  • They travel in a straight line
  • X-ray travel with the speed of light
  • They cannot be reflected, refracted or deflected
  • They show properties of interference, diffraction
  • They do not have any mass or weight
  • They obey inverse square law
  • These are produced by collision of electrons
• Chemical Properties:
  • These induce color changes of several substances
  • Example: Methylene blue gets bleached
  • Cause oxidation of ferrous sulphate to ferric sulphite
  • Causes destruction of the fermenting of enzymes

Read And Learn More: Oral Radiology Question and Answers

• Biological Properties:
  • Excitation – this property is used in the treatment of malignant tumor
  • Germicidal property – This property is used for sterilization oand preservation of food
• Physiochemical Property:
  • Causes blackening of photographic paper on paper
  • This property is known as photographic effect

Question 2. Interaction of X-ray with matter.
Answer.

Interaction of X-ray with matter

• Coherent scattering:
  • Low energy photon passing near atom of outer electron gets scattered without loss of energy
  • Incident photon causes vibration of electrons
  • This electron radiates energy in the form of another X-ray photon
    Significance:
    • 8% of total X-ray interaction are consist of it
    • Effect of it in producing film fog is negligible
• Photoelectric effect:
  • When the incident photon strikes inner orbital electron, it is ejected as photoelectron
  • Vacancy of ineer orbit is filled by electron from higher energy level
  • The ejected electrons travel only a short distance
  • All of the energy of photons is deposited in the absorber
    Significance:
    • Consists of 30% of total interaction
    • It is good for dentist
    • But it is bad for patients due to increased absorption
• Compton effect:
  • Photon interacts with the outer free electron
  • It results in formation of scattered photon of low energy
  • As well as ejection of recoil electron
    Significance:
    • Consists of 62% of total interactions
    • It is good for patients
    • But it is bad for dentist as it causes film fog

Physical properties of X-rays

Properties Of X-Ray Short Answers

Question 1. Inverse Square law.
Answer.

Inverse Square law

• It states that the intensity of the X-ray beam is inversely proportional to the square of the distance from the source to the film
• Increased distance leads to the divergence of the X-ray beam
• Thus number of photons decreases
• As a result, intensity of the X-ray beam diminishes
  1 ∝ 1/d²
  1 = k/d², where k is constant

Question 2. Compton effect.
Answer.

Compton effect

• Photon interacts with the outer free electron
• It results in formation of scattered photon of low energy
• As well as ejection of recoil electron

Compton Effect Significance:

• Consists of 62% of total interactions

• It is good for patient
• But it is bad for dentist as it causes film fog

Characteristics of X-ray radiation

Question 3. Uses of X-ray
Answer.

Uses of X-ray

• Used for diagnostic purposes
• Medicolegal use
• For treatment of tumours
• For treatment of skin diseases
• To improve the quality of oil paints
• For crystallography
• For sterilization of instruments
• As detective measure
• Used in the field of engineering
• As spectroscopy
• As photochemistry
• In the field of radiobiology

Question 4. Coherent scattering.
Answer.

Coherent scattering

• Low energy photon passing near atom of outer electron gets scattered without loss of energy
• Incident photon causes vibration of electrons
• This electron radiates energy in the form of another X-ray photon

Coherent Scattering Significance:

• 8% of total X-ray interaction are consist of it
• Effect of it in producing film fog is negligible

Biological effects of X-rays

Properties Of X-Ray Viva Voce

• X-ray have neutral charges
• Velocity of x-ray is equal to that of light

Radiation Physics Definitions

• Ionization
  • The conversion of an atom into an ion is called Ionization
• Ionizing radiation
  • It is defined as radiation that is capable of producing ions by removing or adding electrons to an atom
• Resolution
  • Resolution is the ability of a radiograph to record separate structures that are close together

Radiation physics in radiology

Radiation Physics Important Notes

• The Conversion of an atom into an ion is called Ionization
  • The radiation, that brings about the ionization of atoms, is called ionizing radiation.
• Radiation is of two types
  • Particulate
    • Particulate radiation consists of atomic nuclei that transmit kinetic energy using their small masses moving at very high velocities Eg: Alpha rays, Beta rays, and Cathode rays
    • Alpha rays consist of a high-speed stream of doubly ionized helium nuclei.
    • Alpha rays have higher LET, thus they are more damaging to the biological systems than X-rays.
  • Non – particulate/electromagnetic
    • Electromagnetic radiation is produced when the velocity of an electrically charged particle is alerted Eg: Radio, TV, Microwaves, infrared, Visible, Ultraviolet, X-rays, Gamma, and Cosmic rays.
    • The above examples are in the increasing order of their energy and decreasing order of their wavelengths.
• Types of electromagnetic radiation
  • Ionizing radiation
  • Nonionizing radiation

Read And Learn More: Oral Radiology Question and Answers

Radiation Physics Short Essays

Question 1. Electromagnetic radiation.
Answer.

Electromagnetic radiation

• It is a combination of electric & magnetic fields
• Generated when the velocity of an electrically charged particle is altered.

Radiation Physics Types:

• Ionizing radiation
• Nonionizing radiation

Radiation Physics Properties:

• Travel in a straight line
• They travel at the speed of light
  • They neither have mass nor weight
  • They transfer energy from place to place in the form of photons
  • They obey the inverse square law
  • These are invisible radiations

Basics of radiation physics

Question 2. Electromagnetic Spectrum
Answer.

Electromagnetic Spectrum

It comprises of the following radiations

Short Answers

Question 1. Ionizing radiation
Answer.

Ionizing radiation

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

Ionizing radiation Classification:

• Particulate radiation.
  • This transmits kinetic energy by extremely fast-moving small masses
  • Types are electron, alpha, protons & neutrons
• Electromagnetic radiation
  • It is the propagation of wave-like energy through space or matter

Principles of radiation physics

Question 2. Timer
Answer.

Timer

• A timer is built into high high-voltage circuit to control the duration of the X-ray exposure
• The electronic timer controls the length of time that high voltage is applied to the tube and the time during which tube current flows and x-rays are produced
• Some X-ray machine timers are calibrated in fractions of a second whereas others are expressed as the number of pulses in an exposure
• The number of pulses divided by 60 gives the exposure time in seconds

Question 3. Exposure time
Answer.

Exposure time

• It is one of the factors controlling X-ray beam
• Changing the exposure time modifies the duration of the exposure and thus the number of photons generated
• When the exposure time is doubled, the number of photons generated at all energies in the X-ray emission spectrum is doubled
• The range of photon energies is unchanged.

Radiation physics short notes

Question 4. Resolution
Answer.

Resolution

• Resolution is the ability of a radiograph to record separate structures that are close together
• It is measured by radiographing an object made up of a series of thin lead strips with alternating radiolucent spaces of the same thickness
• The group of lines and spaces are arranged in test targets in order of increasing the number of lines and spaces per millimeter
• It is measured as the highest number of line pairs per millimeter that can be distinguished on the resultant radiograph when examined with low-power magnification

Viva Voice

• X-rays were discovered by Roentgen in 1895