Radiation Physics Notes and Short Essays

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 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

Radiation Physics Short Essays

Question 1. Electromagnetic radiation.
Answer.

Electromagnetic radiation

Radiation Physics Types:

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

Oral Radiology Radiation Physics Scheme of electomagnetic radiation

Question 2. Electromagnetic Spectrum
Answer.

Electromagnetic Spectrum

It comprises of the following radiations

Electromagnetic spectrum 2

Radiation Physics

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

Oral Radiology Radiation Physics An ion pair is fromed when an electron is removed

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.

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