ARRT RADIOGRAPHY EXAM BANK –
COMPREHENSIVE EXAM WITH ANSWERS
AND RATIONALES
1. The primary controlling factor for radiographic
density (overall image darkness) is:
A) Kilovoltage peak (kVp)
B) Milliamperage-seconds (mAs)
C) Source-to-image distance (SID)
D) Grid ratio
Correct answer: B
Rationale: mAs directly controls the quantity of x-rays
produced, which determines radiographic density
(optical density) on the image.
2. Which interaction between x-ray photons and
matter is primarily responsible for image contrast in
diagnostic radiography?
A) Compton scattering
B) Photoelectric effect
C) Coherent scattering
D) Pair production
,Correct answer: B
Rationale: The photoelectric effect produces high
subject contrast because it depends strongly on
atomic number (Z) and occurs more in bone than soft
tissue.
3. A radiograph is taken at 40 inches SID and 5 mAs.
If the SID is changed to 72 inches, what new mAs is
required to maintain the same exposure to the image
receptor?
A) 1.5 mAs
B) 2.8 mAs
C) 9 mAs
D) 16.2 mAs
Correct answer: D
Rationale: Using the inverse square law with direct
square law formula: mAs2 = mAs1 × (SID2² / SID1²) =
5 × (72²/40²) = 5 × (5184/1600) = 5 × 3.24 = 16.2 mAs.
4. Which of the following is a device used to measure
the output intensity of an x-ray tube?
A) Penetrometer
B) Step wedge
,C) Dosimeter
D) Ionization chamber
Correct answer: D
Rationale: An ionization chamber measures exposure
(mR) and is used for quality control to ensure
consistent x-ray output.
5. The annual effective dose limit for a radiographer
(occupational exposure) is:
A) 0.5 mSv
B) 5 mSv
C) 20 mSv
D) 50 mSv
Correct answer: D
Rationale: NRC and ICRP recommend 50 mSv (5 rem)
annual effective dose limit for occupational exposure;
10% of that for minors and declared pregnant women
(0.5 mSv/month).
6. Which grid error results in decreased density at
the periphery of the image but normal density in the
center?
A) Upside-down focused grid
, B) Off-level grid
C) Off-focus grid
D) Off-center grid
Correct answer: D
Rationale: Off-center grid error (lateral decentering)
causes decreased density at the edges (grid cutoff
peripherally) with normal density centrally.
7. The phenomenon of differential absorption of x-
rays by different tissues creates:
A) Scatter radiation
B) Radiographic contrast
C) Penumbra
D) Quantum mottle
Correct answer: B
Rationale: Radiographic contrast is the visible
difference between adjacent densities, created by
differential absorption (bone absorbs more, air
absorbs less).
8. Which of the following is a characteristic of a high-
frequency generator compared to a single-phase
generator?
COMPREHENSIVE EXAM WITH ANSWERS
AND RATIONALES
1. The primary controlling factor for radiographic
density (overall image darkness) is:
A) Kilovoltage peak (kVp)
B) Milliamperage-seconds (mAs)
C) Source-to-image distance (SID)
D) Grid ratio
Correct answer: B
Rationale: mAs directly controls the quantity of x-rays
produced, which determines radiographic density
(optical density) on the image.
2. Which interaction between x-ray photons and
matter is primarily responsible for image contrast in
diagnostic radiography?
A) Compton scattering
B) Photoelectric effect
C) Coherent scattering
D) Pair production
,Correct answer: B
Rationale: The photoelectric effect produces high
subject contrast because it depends strongly on
atomic number (Z) and occurs more in bone than soft
tissue.
3. A radiograph is taken at 40 inches SID and 5 mAs.
If the SID is changed to 72 inches, what new mAs is
required to maintain the same exposure to the image
receptor?
A) 1.5 mAs
B) 2.8 mAs
C) 9 mAs
D) 16.2 mAs
Correct answer: D
Rationale: Using the inverse square law with direct
square law formula: mAs2 = mAs1 × (SID2² / SID1²) =
5 × (72²/40²) = 5 × (5184/1600) = 5 × 3.24 = 16.2 mAs.
4. Which of the following is a device used to measure
the output intensity of an x-ray tube?
A) Penetrometer
B) Step wedge
,C) Dosimeter
D) Ionization chamber
Correct answer: D
Rationale: An ionization chamber measures exposure
(mR) and is used for quality control to ensure
consistent x-ray output.
5. The annual effective dose limit for a radiographer
(occupational exposure) is:
A) 0.5 mSv
B) 5 mSv
C) 20 mSv
D) 50 mSv
Correct answer: D
Rationale: NRC and ICRP recommend 50 mSv (5 rem)
annual effective dose limit for occupational exposure;
10% of that for minors and declared pregnant women
(0.5 mSv/month).
6. Which grid error results in decreased density at
the periphery of the image but normal density in the
center?
A) Upside-down focused grid
, B) Off-level grid
C) Off-focus grid
D) Off-center grid
Correct answer: D
Rationale: Off-center grid error (lateral decentering)
causes decreased density at the edges (grid cutoff
peripherally) with normal density centrally.
7. The phenomenon of differential absorption of x-
rays by different tissues creates:
A) Scatter radiation
B) Radiographic contrast
C) Penumbra
D) Quantum mottle
Correct answer: B
Rationale: Radiographic contrast is the visible
difference between adjacent densities, created by
differential absorption (bone absorbs more, air
absorbs less).
8. Which of the following is a characteristic of a high-
frequency generator compared to a single-phase
generator?
