ARRT subcategory · 13% of scored exam
Image Acquisition and Evaluation
Covers the factors that affect radiographic quality (mAs, kVp, OID, SID, focal spot, grids and more), technique charts, automatic exposure control, digital imaging characteristics, image identification, and image evaluation. ARRT says receptor exposure and spatial resolution where some texts say density and detail. Its factor table adds image contrast and subject contrast columns in the 2027 outline, from 1 March 2027. CR items such as radiation fog are on the 2022 outline only.
26 of 200 scored questions under the 2022 content specification, in force through 28 February 2027. From 1 March 2027, the 2027 content specification lists 26 of 200.
Sample question
A free sample question, written for this page, like those in the 367-question Image Acquisition bank. Read it, pick your answer, then expand the rationale.
An exposure is made at 80 kVp and 4 mAs at 72 inches SID. To keep receptor exposure constant at 40 inches SID, what new mAs is required?
Show answer and full rationale
Correct answer: C. 1.2 mAs
A, Incorrect: 1 mAs is about 19% less than the formula requires. Apply the square law.
B, Incorrect: Distance is decreasing, so mAs should decrease, and by more than half. 2 mAs is still too high.
C, Correct: Correct. Square law: 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. This is the formula reversed: a shorter distance requires less mAs, not more.
Topics to study in this subcategory
Our study list, in common study terms where those differ from ARRT's. ARRT's content outline is the official list.
- kVp, receptor exposure and contrast
- mAs and receptor exposure
- SID and the square law for constant receptor exposure
- The 15% rule (a textbook rule ARRT's outline does not name)
- Grids and grid conversion factors
- Digital imaging: pixels, detector elements, bit depth
- Exposure indicator and gross exposure errors
- Automatic exposure control: detector selection, exposure adjustment
- Image evaluation: contrast, spatial resolution, distortion, artifacts
Drill the full 367-question bank.
The free tier includes a 50-question quiz and a 200-question sample exam, 241 different questions in all. A paid plan unlocks all 2,584 ARRT-style questions, unlimited generated mock exams, and drills in this subcategory that adapt question order to you. Paid plans open soon.
Frequently asked questions
How many Image Acquisition questions are on the ARRT Radiography Boards?
The Image Acquisition and Evaluation subcategory is 26 of the 200 scored questions under the 2022 content specification, in force through 28 February 2027, about 13% of the scored exam. From 1 March 2027, the 2027 content specification lists 26 of 200. The full Radtechprepper practice bank contains 367 questions in this category, giving you ample room to drill until the patterns are second nature.
What topics are in the Image Acquisition subcategory?
Our study list for Image Acquisition starts with: kVp, receptor exposure and contrast; mAs and receptor exposure; SID and the square law for constant receptor exposure; The 15% rule (a textbook rule ARRT's outline does not name); Grids and grid conversion factors. The official list is the content outline in ARRT Radiography Content Specifications. Our list uses common study terms in places, and the outline is what ARRT publishes.
How should I study for the Image Acquisition subcategory?
Start with the chapter overviews listed on this page, which cover the core concepts in plain English. Then drill questions, pause on every miss, read the rationale, and re-drill the same topic the next day. Space your review over several days instead of cramming.