Radiation Safety and Applied Radiobiology ARRT Review

A set of practice flashcards covering X-ray physics, target interactions, biological effects, and radiation protection standards based on the ARRT Radiation Safety review lecture.

How much total time is allocated for the ARRT exam?

4 hours, which translates to 240 minutes.

What is the first task an examinee must complete at the start of the ARRT exam?

The Nondisclosure Agreement (NDA), which takes approximately 2 minutes and must not be ignored to avoid a first-time failure/timed-out blue screen.

In the ARRT exam, how many questions are scored and how many are pilot items?

There are 200 scored items and 30 pilot items, for a total of 230 questions.

What percentage of the scored items on the ARRT exam focus on radiation safety?

$25\%$ of the scored items, which accounts for 50 questions.

Which SI unit is used to express exposure in the ARRT exam?

$Coulomb\,per\,kilogram\, (C/kg)$ of electrical charge per kilogram of air.

What are the four ideal conditions required for X-ray production inside the tube?

A source of electrons (filament), a focusing of electrons (focusing cup), acceleration of electrons ($kV$), and deceleration of electrons (collision with the anode).

What energy level is required to produce useful characteristic X-rays in a tungsten-rhenium alloy target?

At least $69\,kV$.

What is the relationship between beam frequency and wavelength?

They share an inverse relationship: higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths.

What formula represents the inverse square law?

$\frac{I_1}{I_2} = \frac{(D_2)^2}{(D_1)^2}$.

What happens to the intensity of the X-ray beam if the distance is doubled?

The intensity is reduced to one-fourth ($25\%$\text{) of its original value.}

Which photon interaction with matter results in excitation but not ionization at low energy levels?

Coherent (also known as classical, Thompson, or Rayleigh) scattering, occurring between $1\,keV$ and $50\,keV$.

Which interaction is responsible for white/light areas on a radiograph and represents the total absorption of the incident photon?

Photoelectric absorption.

How is attenuation defined in the context of the X-ray beam passing through tissue?

The reduction in the overall intensity of the X-ray beam due to absorption and scatter.

According to NCRP Report number 116, what is the unit for absorbed dose and air kerma?

The Gray ($Gy$).

What is the formula used to calculate Equivalent Dose ($EQD$)?

$EQD = D \times W_R$, where $D$ is the dose received and $W_R$ is the radiation weighting factor.

Under the Law of Bergonie and Tribondeau, when are cells most sensitive to radiation?

When they are immature, undifferentiated, and rapidly dividing.

Which model is considered the most conservative in radiation protection and assumes no level of radiation is safe?

The linear non-threshold ($LNT$) model.

Most radiation interactions in a cell occur with which molecule?

Water ($H_2O$), making up $80-85\%$ of the cell content, leading to indirect effects.

What toxic substance is formed during the radiolysis of water that can cause cell death?

Hydrogen peroxide ($H_2O_2$) resulting from the recombination of free radicals.

Which blood cell type is the most sensitive to radiation?

Lymphocytes.

What are the three cardinal principles of radiation safety, and which is the most effective?

Time, Distance, and Shielding; Distance is the most effective.

What is the minimum source-to-skin distance ($SSD$) for portable/mobile fluoroscopy units?

$12\,inches$ (or $30\,cm$).

What is the NCRP recommendation for the lead equivalence of a protective apron?

$0.5\,mm$ of lead or lead equivalent.

What is the maximum allowable leakage radiation from the tube housing at a distance of $1\,meter$?

$100\,mR/hr$.

Which radiation detection device is the most popular dosimeter in use today for monitoring personnel?

The Optically Stimulated Luminescence ($OSL$) dosimeter.