Quality Control Concerns for New Generations of CT, MRI, & PET

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1 Quality Control Concerns for New Generations of CT, MRI, & PET David W. Jordan, Ph.D. Sr. Medical Physicist, UH Case Medical Center Clinical Assistant Professor, CWRU

2 Disclosures No financial disclosures or industry relationships Member of organizations discussed: AAPM TG-126 (PET) AAPM WGMRQA (MRI)

3 Objectives Understand the typical elements of a QC program for CT, MRI, and PET equipment. Anticipate the QC challenges created by new imaging technology advances.

4 Outline Overview of current QC procedures for CT, MRI, and PET. Discuss new CT technology : wide/cone beams and iterative reconstruction Discuss new MRI technology: parallel imaging and massively multichannel coils Discuss new PET technology: time of flight and alternatives to PMT detectors

5 QC Perspectives Medical Physicist Imaging Technologist

6 QC Goals Obtain data to characterize performance (and dose) Obtain data to optimize performance Monitor constancy of function/performance

7 Meta QC: What is the Quality of your Quality Control? Does each test contribute to characterization, and/or optimization, and/or constancy?

8 Meta QC: What is the Quality of your Quality Control? Is each test: Clinically relevant? Feasible? (time, cost) Sensitive? Specific?

9 Meta QC: What is the Quality of your Quality Control? Is each/every test mandated by: ACR? AAPM TG # such and such? Joint Commission? ACRIN / CRO? Ohio Department of Health? Etc.?

10 CT

11 Current QC: CT QC phantom measurements: CT # accuracy/linearity Uniformity Noise / CNR / SNR High & low contrast Scanner alignment

Current QC: CT Dose: CTDI 100 16 & 32 cm dia.

12 Current QC: CT Dose: CTDI & 32 cm dia. cylinders (10-15 cm thick) Measure scanner output

13 CT Advances: Iterative Recon M.J. Willemink et al., Iterative reconstruction techniques for computed tomography Part 1: technical principles., Eur. Radiol. 23(6), (2013).

14 CT IR QC Challenges IR techniques manipulate image noise Radiologists report texture concerns with reconstructed images Details of reconstruction proprietary Is CT # manipulated / better / worse?

15 CT IR QC: What and How To Test? Characterization? Optimization? Constancy? Clinically relevant? Feasible? Sensitive? Specific?

com/minicat-technical-specifications/ Toshiba Medical

16 CT Advances: Wide Beams 100-mm CTDI pencil chamber Xoran Technologies, Toshiba Medical Systems, anguage=en

17 Wide Beam QC Challenges CTDI 100 inadequate for dose (scanner output) measurements Proposed alternatives (TG-111) cumbersome: Large/long phantom Non-standard equipment & metrics TG 200 working on feasible implementation

18 C. Descamps, M. Gonzalez, E. Garrigo, A. Germanier, and D. Venencia, Measurements of the dose delivered during CT exams using AAPM Task Group Report No. 111., J. Appl. Clin. Med. Phys. 13(6), 3934 (2012).

19 Wide/Cone Beam CT Dose: How To Test? Characterization? Optimization? Constancy? Clinically relevant? Feasible? Sensitive? Specific?

20 CT Coming Attractions CT performance assessment including iterative reconstructions: AAPM Task Group 223 Established 2012 Ehsan Samei, Chair Development of wide/cone beam dosimetry: AAPM Task Group 200 Established 2010 Donovan Bakalyar, Chair

21 MRI

22 Magnet homogeneity Scanner performance Slice position/thickness Geometric accuracy Resolution Artifacts Performance of all individual coils SNR, uniformity Current QC: MRI

23 MRI Advances: Parallel Imaging R. Hashemi, W.G. Bradley, and C.J. Lisanti, MRI: The Basics (Lippincott Williams & Wilkins, 2010).

24 Parallel MRI QC Challenges

25 Parallel MRI: What/How To Test? Characterization? Optimization? Constancy? Clinically relevant? Feasible? Sensitive? Specific?

26 MRI Advances: Coils T. Niendorf et al., Progress and promises of human cardiac magnetic resonance at ultrahigh fields: a physics perspective., J. Magn. Reson. 229, (2013).

27 Coil QC Challenges State of the art coil arrays have up to 128 channels Many MORE individual elements in some arrays! Existing methods: Simple/aggregated scan may miss problems Thorough testing can take hours per coil, typical scanner has coils

28 MRI Coil Arrays: What/How To Test? Characterization? Optimization? Constancy? Clinically relevant? Feasible? Sensitive? Specific?

29 MRI Coming Attractions Parallel Imaging Technology & QC: AAPM Task Group 118 Established 2005 Nathan Yanasak, Chair RF Coil QC (and other topics): AAPM WG on MR Testing and QA Established 2005 Joseph Och, Chair

30 PET

31 Phantom images SUV accuracy Contrast cold/ warm /hot objects Resolution Count rate response vs. activity Sensitivity Spatial resolution Corrections Current QC: PET

32 PET Advances: Time of Flight Diagram of line of response vs segment of response

33 TOF-PET: What/How To Test? Characterization? Optimization? Constancy? Clinically relevant? Feasible? Sensitive? Specific?

34 PET Advances: New Detectors

35 Non-PMT Detector QC Challenges Air-cooled arrays performance depends on ambient temperature Detection efficiency and speed affect sensitivity, count rate performance Enable or require use of different scintillators? Effect of timing resolution?

36 Post-PMT PET: What/How To Test? Characterization? Optimization? Constancy? Clinically relevant? Feasible? Sensitive? Specific?

37 PET Coming Attractions PET-CT Acceptance Testing & QC: AAPM Task Group 126 Established 2005 Osama Mawlawi, Chair

38 Review of Objectives New technology developments: CT: iterative recon, wide beams, dose reduction technology MRI: parallel imaging and multichannel coils PET: time of flight and non-pmt detectors New technologies may or may not be adequately addressed by existing QC methods

39 Questions? Thank you!

2017 ACR Computed Tomography Quality Control Manual FAQS

Updated 11-15-2017 2017 ACR Computed Tomography Quality Control Manual FAQS Q. The updated 2017 ACR Computed Tomography Quality Control Manual has been released. (Visit www.acr.org/education/education-catalog.)