GXMO Radiation Physics and Safety 4

Question 1

What is Bremsstrahlung radiation?

Accepted Answer

X-rays produced when high-speed electrons are slowed and deflected by the atomic nucleus

Answer

Bremsstrahlung (German for 'braking radiation') is produced when fast-moving electrons are decelerated and deflected by the electric field of the target nucleus, releasing energy as x-ray photons.

Question 2

A radiographer increases kVp while reducing mAs to maintain similar image density. What effect does this have on patient dose?

Accepted Answer

Patient dose decreases

Answer

Increasing kVp and reducing mAs (the 15% rule) generally reduces patient entrance skin dose because higher-energy photons penetrate tissue more efficiently, requiring less total beam output.

Question 3

Which of the following is an example of a stochastic radiation effect?

Accepted Answer

Radiation-induced cancer

Answer

Stochastic effects like cancer induction have a probability of occurrence that increases with dose but no threshold; severity is independent of dose.

Question 4

What is the recommended minimum source-to-skin distance (SSD) for stationary x-ray equipment used in general radiography?

Accepted Answer

38 cm (15 inches)

Answer

Federal regulations (21 CFR 1020.30) require a minimum SSD of 38 cm (15 inches) for stationary general-purpose x-ray equipment to limit skin dose.

Question 5

What type of radiation survey instrument is best suited for detecting low levels of contamination or locating the edge of a radiation field?

Accepted Answer

Geiger-Müller (GM) detector

Answer

GM detectors are highly sensitive to low radiation levels and produce audible clicks for each ionizing event, making them ideal for contamination surveys and field edge detection.

(GXMO) General X-Ray Machine Operator Practice Test

(GXMO) General X-Ray Machine Operator Practice Test

GXMO Radiation Physics and Safety 4