Image Production · ARRT 2025
Radiography Quality Control
kVp accuracy (±5%), timer accuracy, focal spot size, beam alignment, AEC reproducibility, and the QC schedule for the ARRT Radiography Boards.
Overview
Quality Control is the systematic guardian work of radiography. The chapter is built around five tested tolerances and a test schedule (daily, weekly, monthly, annually) that ensures every exposure stays within manufacturer specs. The ARRT registry tests this material as both numerical recall and procedural reasoning.
The core tolerances. kVp accuracy: ±5% of the indicated value (a 100 kVp setting should produce 95–105 kVp actual). Timer accuracy: ±5% of the indicated time. mA linearity: linear within 10% across the mA range. Focal spot size: ±50% of stated size, a 1.0 mm focal spot can measure 0.5–1.5 mm and still pass. Beam-light field alignment: within 2% of SID, at 40 inches, beam edge can deviate up to 0.8 inches from the light field edge. Half-Value Layer (HVL): ≥ 2.5 mm Al at 80 kVp (proves filtration is adequate).
AEC reproducibility: exposures from the same setting should reproduce within 5%. Reciprocity: exposures of equal mAs (varied by mA × time combinations) should produce equal density within 10%. Grid uniformity: density across the grid should be uniform within 10%. The QC schedule by frequency: daily processor checks (sensitometry), weekly cassette/IR checks, monthly AEC reproducibility, semi-annual collimator and beam alignment, annual kVp/mA/timer/focal spot testing. Modern CR/DR adds digital-specific QC: dead pixel mapping, exposure index calibration, monitor luminance and grayscale calibration. Personnel monitoring devices (TLD or OSL badges) read monthly or quarterly. Lead apron inspection: every six months, fluoroscopy aprons reviewed under fluoroscopy for cracks at the seams.
What you’ll learn in this chapter
The 13 lessons in this chapter break down as follows. The full lesson content is unlocked when you start a free account.
The Mission
- Why QC Is Non-Negotiable
- Anatomy of a QC Program
Primary Beam Calibration
- kV Accuracy & mA Linearity
- Timer Accuracy & Reproducibility
- HVL & Focal Spot Size
- The Master Calibration Checklist
Accessories & Digital QC
- Cassettes, Screens, Grids, Illuminators
- Digital QC Schedule
- The QC Team
Knowledge Check
- Question 1 of 4 Quiz
- Question 2 of 4 Quiz
- Question 3 of 4 Quiz
- Question 4 of 4 Quiz
Key terms in this chapter
These are the 7 terms most likely to appear on the ARRT registry from this chapter. Use them as a flashcard pre-quiz.
- kVp Accuracy
- Tolerance: ±5% of the indicated value. A 100 kVp setting should produce 95–105 kVp actual.
- Timer Accuracy
- Tolerance: ±5% of the indicated time. Tested with a spinning-top test or motorized timer.
- Focal Spot Tolerance
- Tolerance: ±50% of stated size. A 1.0 mm focal spot can measure 0.5–1.5 mm and still pass QC.
- Beam-Light Field Alignment
- Tolerance: within 2% of SID. At 40 inches, beam edge can deviate up to 0.8 inches from light field edge.
- Half-Value Layer (HVL)
- Thickness of aluminum that reduces beam intensity by 50%. Must be ≥ 2.5 mm Al at 80 kVp.
- Reciprocity Test
- Verifies that exposures of equal mAs (different mA × time combinations) produce equal density.
- Sensitometry
- Daily processor QC. A controlled film exposure measured for base+fog, mid-density, and contrast.
Sample practice question: Equipment QA
One free sample from the 93-question Equipment QA bank. See the format, the rationale style, and the difficulty before you sign up.
Annual QC testing reveals that a generator set to 100 kVp is producing an actual peak voltage of 93 kVp. Is this within the acceptable tolerance?
Show answer and rationale
A, Incorrect: kVp tolerance is ±5%, not ±10%.
B, Correct: Correct. The kVp accuracy tolerance is ±5% of the indicated value. A 100 kVp setting must produce 95–105 kVp actual. 93 kVp is below the lower limit and the generator must be serviced.
C, Incorrect: kVp tolerance is ±5%, not ±15%. ±15% is the threshold for the 15% density rule, not QC.
D, Incorrect: kVp tolerance is ±5%, not ±2%. Timer tolerance is also ±5%.
Read the full chapter, free.
The free tier unlocks one complete chapter (13 lessons), 50 practice questions, and 1 sample timed exam. No credit card required.
Frequently asked questions
What does the ARRT Radiography Image Production category cover?
Quality Control is the systematic guardian work of radiography. The chapter is built around five tested tolerances and a test schedule (daily, weekly, monthly, annually) that ensures every exposure stays within manufacturer specs. The ARRT registry tests this material as both numerical recall and procedural reasoning.
How many lessons are in the Radiography Quality Control chapter?
This chapter contains 13 lessons across 4 sections, plus a knowledge-check quiz at the end. The full lesson content is unlocked with a Premium subscription. The free tier includes the first chapter complete.
Is this chapter aligned with the ARRT 2025 Content Specifications?
Yes. Every chapter on this site maps directly to the ARRT Radiography Content Specifications effective 2025. This chapter falls under the Image Production domain of the official ARRT exam blueprint.