X-ray Machine Operator
Introduction
This simulation mirrors the current state-level X-ray Machine Operator certification
examination.
The 100-item set spans seven weighted domains: radiation physics & safety, equipment
operation, patient positioning & imaging procedures, image production & quality
assurance, state regulatory compliance, radiation protection & biology, and patient
care/ethics.
Every question is original, scenario-based, and aligned with 2024 licensing standards to
support mastery-level performance.
Examination-length set: 100 original questions
Question 1:
If the total filtration of a diagnostic tube housing is increased from 2.5 mm Al to 3.5 mm
Al, the resulting half-value layer will
A. decrease by approximately 10 %.
B. remain unchanged because kVp is unchanged.
C. increase.
D. decrease by one half.
Answer: C. increase.
Solution: Added filtration hardens the beam; HVL must increase. Option D implies a 50
% drop in HVL, which is incorrect.
Question 2:
A control panel displays “Rotor Fault” immediately after the rotor button is pressed. The
operator’s first action should be to
A. increase kVp by 10 %.
B. depress the exposure switch fully to override the interlock.
C. check the rotor cable connection and restart the warm-up sequence.
D. decrease mAs by 50 %.
Answer: C. check the rotor cable connection and restart the warm-up sequence.
Solution: A rotor fault indicates a mechanical or electrical failure; overriding could
damage the tube. Options A and D ignore the fault.
Question 3:
Which interaction contributes most to patient dose during a 75 kVp chest radiograph?
pg. 1
,A. Coherent scatter
B. Photoelectric effect
C. Compton scatter
D. Pair production
Answer: C. Compton scatter
Solution: At 75 kVp, Compton events dominate in soft tissue. Pair production requires
≥1.02 MeV.
Question 4:
A 200 mA, 100 ms exposure at 80 kVp produces 40 mR at the receptor. If mA is
increased to 400 mA and time is reduced to 50 ms, the new exposure will be
A. 20 mR
B. 40 mR
C. 80 mR
D. 160 mR
Answer: B. 40 mR
Solution: mAs remains 20 in both cases; output is unchanged.
Question 5:
The annual occupational whole-body dose limit for a non-pregnant operator is
A. 1 mSv
B. 5 mSv
C. 50 mSv
D. 500 mSv
Answer: C. 50 mSv
Solution: NCRP #116 sets 50 mSv per year. 5 mSv is the fetal limit.
Question 6:
Which change best reduces motion unsharpness in a crying pediatric chest?
A. Increase SID to 180 cm
B. Use the shortest exposure time (<5 ms) available
C. Decrease kVp to 60
D. Apply a compression band
Answer: B. Use the shortest exposure time (<5 ms) available
Solution: Short time freezes motion. Compression bands are unsafe for pediatric chest.
Question 7:
An operator notices a 1 cm dark band at the leading edge of every CR image. The most
probable cause is
pg. 2
, A. grid motion failure.
B. plate lag from incomplete erase.
C. static electricity.
D. off-focus radiation.
Answer: B. plate lag from incomplete erase.
Solution: Residual latent image from a prior high-dose exam appears as a bright or dark
band in the scan direction.
Question 8:
State regulations require that leakage radiation from a diagnostic tube housing must not
exceed
A. 0.1 mGy in any hour at 50 cm.
B. 0.25 mGy in any hour at 1 m.
C. 1 mGy per week at the console.
D. 5 µSv per exposure at the patient surface.
Answer: B. 0.25 mGy in any hour at 1 m.
Solution: Federal and state rules adopt 0.25 mGy air-kerma in one hour at 1 m.
Question 9:
During a lateral lumbar spine, the operator forgets to remove the grid from a 25 cm
thick patient. The most likely outcome is
A. underexposed image.
B. overexposed image.
C. grid cutoff artifact.
D. quantum mottle.
Answer: A. underexposed image.
Solution: Grid absorbs scatter; without a compensating increase in mAs, the image will
be light.
Question 10:
Which positioning line is perpendicular to the IR for a lateral cervical spine?
A. Orbitomeatal line
B. Infraorbitomeatal line
C. Interpupillary line
D. Mentomeatal line
Answer: C. Interpupillary line
Solution: The interpupillary (or inter-orbital-meatal) line must be perpendicular to
avoid rotation.
pg. 3
Introduction
This simulation mirrors the current state-level X-ray Machine Operator certification
examination.
The 100-item set spans seven weighted domains: radiation physics & safety, equipment
operation, patient positioning & imaging procedures, image production & quality
assurance, state regulatory compliance, radiation protection & biology, and patient
care/ethics.
Every question is original, scenario-based, and aligned with 2024 licensing standards to
support mastery-level performance.
Examination-length set: 100 original questions
Question 1:
If the total filtration of a diagnostic tube housing is increased from 2.5 mm Al to 3.5 mm
Al, the resulting half-value layer will
A. decrease by approximately 10 %.
B. remain unchanged because kVp is unchanged.
C. increase.
D. decrease by one half.
Answer: C. increase.
Solution: Added filtration hardens the beam; HVL must increase. Option D implies a 50
% drop in HVL, which is incorrect.
Question 2:
A control panel displays “Rotor Fault” immediately after the rotor button is pressed. The
operator’s first action should be to
A. increase kVp by 10 %.
B. depress the exposure switch fully to override the interlock.
C. check the rotor cable connection and restart the warm-up sequence.
D. decrease mAs by 50 %.
Answer: C. check the rotor cable connection and restart the warm-up sequence.
Solution: A rotor fault indicates a mechanical or electrical failure; overriding could
damage the tube. Options A and D ignore the fault.
Question 3:
Which interaction contributes most to patient dose during a 75 kVp chest radiograph?
pg. 1
,A. Coherent scatter
B. Photoelectric effect
C. Compton scatter
D. Pair production
Answer: C. Compton scatter
Solution: At 75 kVp, Compton events dominate in soft tissue. Pair production requires
≥1.02 MeV.
Question 4:
A 200 mA, 100 ms exposure at 80 kVp produces 40 mR at the receptor. If mA is
increased to 400 mA and time is reduced to 50 ms, the new exposure will be
A. 20 mR
B. 40 mR
C. 80 mR
D. 160 mR
Answer: B. 40 mR
Solution: mAs remains 20 in both cases; output is unchanged.
Question 5:
The annual occupational whole-body dose limit for a non-pregnant operator is
A. 1 mSv
B. 5 mSv
C. 50 mSv
D. 500 mSv
Answer: C. 50 mSv
Solution: NCRP #116 sets 50 mSv per year. 5 mSv is the fetal limit.
Question 6:
Which change best reduces motion unsharpness in a crying pediatric chest?
A. Increase SID to 180 cm
B. Use the shortest exposure time (<5 ms) available
C. Decrease kVp to 60
D. Apply a compression band
Answer: B. Use the shortest exposure time (<5 ms) available
Solution: Short time freezes motion. Compression bands are unsafe for pediatric chest.
Question 7:
An operator notices a 1 cm dark band at the leading edge of every CR image. The most
probable cause is
pg. 2
, A. grid motion failure.
B. plate lag from incomplete erase.
C. static electricity.
D. off-focus radiation.
Answer: B. plate lag from incomplete erase.
Solution: Residual latent image from a prior high-dose exam appears as a bright or dark
band in the scan direction.
Question 8:
State regulations require that leakage radiation from a diagnostic tube housing must not
exceed
A. 0.1 mGy in any hour at 50 cm.
B. 0.25 mGy in any hour at 1 m.
C. 1 mGy per week at the console.
D. 5 µSv per exposure at the patient surface.
Answer: B. 0.25 mGy in any hour at 1 m.
Solution: Federal and state rules adopt 0.25 mGy air-kerma in one hour at 1 m.
Question 9:
During a lateral lumbar spine, the operator forgets to remove the grid from a 25 cm
thick patient. The most likely outcome is
A. underexposed image.
B. overexposed image.
C. grid cutoff artifact.
D. quantum mottle.
Answer: A. underexposed image.
Solution: Grid absorbs scatter; without a compensating increase in mAs, the image will
be light.
Question 10:
Which positioning line is perpendicular to the IR for a lateral cervical spine?
A. Orbitomeatal line
B. Infraorbitomeatal line
C. Interpupillary line
D. Mentomeatal line
Answer: C. Interpupillary line
Solution: The interpupillary (or inter-orbital-meatal) line must be perpendicular to
avoid rotation.
pg. 3
