Performance Testing of CT (Computer Tomography) using ACR (American College of Radiology) Phantom

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