ARRT category · 22% of exam
Image Acquisition and Evaluation
Tests technical factor selection (kVp, mAs), the 15% rule, inverse square law, image quality (density, contrast, recorded detail, distortion), grid use, and CR/DR digital workflow. Approximately 22% of the ARRT exam.
Sample question
One free question from the 98-question Image Acquisition bank. Read it, pick your answer, then expand the rationale.
An adult chest x-ray is performed at 80 kVp and 4 mAs at 72 inches SID. To maintain density at 40 inches SID, what new mAs is required?
Show answer and full rationale
Correct answer: C. 1.2 mAs
A, Incorrect: 1 mAs would result in significant underexposure. Apply the density maintenance formula.
B, Incorrect: Distance is decreasing, so mAs should decrease, but not by half.
C, Correct: Correct. Density maintenance formula: mAs₂ = mAs₁ × (SID₂² / SID₁²) = 4 × (40² / 72²) = 4 × (1600/5184) = 4 × 0.309 ≈ 1.2 mAs. Closer distance means more intensity, so less mAs is needed.
D, Incorrect: 13 mAs would more than triple the exposure. Reversed formula error, increasing distance requires more mAs, not less.
Topics tested in this category
- kVp and contrast scale
- mAs and density
- The 15% rule
- Inverse square law and density maintenance
- Grid ratios and Bucky factor
- Photostimulable phosphor (PSP) plates
- Histogram analysis and exposure index
- Window width and window level
- Image quality: density, contrast, detail, distortion
Drill the full 98-question bank.
Free tier includes 50 mixed-category questions. Premium unlocks all 1,814 ARRT-style questions, 3 timed mock exams, and adaptive drill sessions in this category.
Frequently asked questions
How many Image Acquisition questions are on the ARRT Radiography Boards?
The Image Acquisition and Evaluation category accounts for approximately 22% of the ARRT Radiography Boards exam, that's roughly 44 of the 200 scored questions on each administration. The full Radtechprepper practice bank contains 98 questions in this category, giving you ample room to drill until the patterns are second nature.
What topics are tested in the Image Acquisition category?
The Image Acquisition category tests: kVp and contrast scale; mAs and density; The 15% rule; Inverse square law and density maintenance; Grid ratios and Bucky factor. The full topic list is in the ARRT Radiography Content Specifications 2025.
How should I study for the Image Acquisition category?
Start with the chapter overviews in this curriculum that map to Image Acquisition, they cover the core concepts in plain English. Then drill questions in the practice bank, pause on every miss, read the rationale, and re-drill the same topic the next day. The ARRT exam rewards spaced repetition more than cram studying.