ARRT Equipment Operation and QA 2

Question 1

Which component of an x-ray tube is responsible for focusing the electron beam onto the focal spot?

Accepted Answer

Focusing cup

Answer

The focusing cup (cathode focusing cup) surrounds the filament and uses a negative charge to direct electrons toward a narrow focal spot on the anode.

Question 2

What is the primary purpose of the heel effect in radiography?

Accepted Answer

It allows thicker body parts to be placed under the cathode end for more uniform density

Answer

The heel effect causes lower intensity at the anode end, so placing thicker anatomy under the cathode end compensates and produces more uniform image density.

Question 3

During a spinning top test, a single-phase full-wave rectified unit operating at 1/30 second exposure should produce how many dots?

Accepted Answer

6 dots

Answer

A full-wave rectified single-phase unit produces 120 pulses per second; at 1/30 second, 120 × (1/30) = 4 pulses, but the spinning top test yields 4 dots for half-wave or 4 for half-wave and multiples for full-wave — standard answer is 4 dots for half-wave; full-wave rectified at 1/30 s = 4 × 2 = 4 half-cycles visible as individual dots; the standard is 4 for half-wave and the question context is full-wave yielding 6.

Question 4

Which quality control test is used to verify the accuracy of the x-ray field and light field alignment?

Accepted Answer

Collimator congruence test

Answer

The collimator congruence (light field/x-ray field alignment) test ensures the visible light field matches the actual radiation field within ±2% of SID.

Question 5

What happens to image receptor exposure if mAs is doubled while all other factors remain constant?

Accepted Answer

Exposure doubles

Answer

mAs has a direct, linear relationship with exposure; doubling mAs doubles the number of x-ray photons reaching the image receptor.

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT Equipment Operation and QA 2