The document outlines the procedures for performing an annual performance evaluation of a computer tomography (CT) scanner using an ACR CT phantom. It involves tests to evaluate positioning accuracy, CT number accuracy, slice thickness, low contrast resolution, high contrast resolution, image uniformity and noise, and distance measurement accuracy. The tests involve scanning the various modules of the ACR phantom using different protocols and recording measurements of CT numbers, slice thicknesses, smallest visible rods, uniformity, artifacts, and resolved bar patterns.

3. Annual Performance Evaluation • Display devices – Video display – Hard-copy display • Dosimetry - Computed Tomography dosimetry index (CTDI) ‏ - Patient radiation dose for representative examinations • Safety evaluation – Visual inspection – Audible/visual signals – Posting requirements – Scattered radiation measurements

4. ACR Performance Phantom

6. 4 3 2 1 20 cm 4 cm Head Foot Alignment CT # Slice width Low contrast resolution Uniformity & noise Distance accuracy & SSP High contrast resolution

9. ACR Performance Phantom

10. Air ≈ -1000 HU Water ≈ 0 HU Polyethylene ≈ -97 HU “ Bone” ≈ +910 HU Acrylic ≈ +120 HU MODULE 1

11. MODULE 1

12. High-resolution chest technique Must see all four BBs Longer wire must have same number of lines above and below (±1) ‏ Wires are 0.5 mm apart in z-direction WW = 1000 WL = 0

14. 12 5 9 4 6 7 8 10 Bar patterns: lp/cm MODULE 4

15. DATA FORM 08/22/08

17. Adult abdomen technique CT number measured in 5 materials CT number of water measured at several scan widths and kVps WW = 400 WL = 0 “ Bone” Water Poly Acrylic Air

18. Adult abdomen technique Scan width measured at several scan widths

19. 08/22/08 DATA FORM

21. 25 mm 6 mm 5 mm 4 mm 3 mm 2 mm Low contrast = 6 HU ± 0.5 HU MODULE 2

22. Adult abdomen and head techniques Record diameter of the smallest set of rods for which all 4 rods can be seen ROI check of absolute contrast using large rod WW = 100 WL = 100

23. DATA FORM 08/22/08

25. MODULE 3 100 mm

26. Adult abdomen and head techniques Measure uniformity and noise Assess for artifacts Measure distance accuracy (optional) ‏ WW = 100 WL = 0

27. DATA FORM 08/22/08

29. 12 5 9 4 6 7 8 10 Bar patterns: lp/cm MODULE 4

30. Adult abdomen, adult head and high-resolution chest techniques Record the first highest frequency bar pattern for which the bars and spaces merge WW = 100 WL  1100

31. WW = 400 WL = 0 CT ART? At soft-tissue window settings these streaks are visible and not of concern

32. DATA FORM 08/22/08

35. Thank You