2/14/2019. Nuclear Medicine Artifacts. Symmetric energy windows

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1 Nuclear Medicine Artifacts SCPMG Medical Imaging Technology & Informatics Medical Physics Group Brian Helbig, MS, DABR 1 2 Symmetric energy windows 3 1

2 Dynamic clinical study Energy peak shift Electrical grounding problem 4 Asymmetric window 5 Symmetric/Asymmetric energy windows - Poor PMT balance and crystal hydration 6 2

3 Asymmetric energy window fault in energy correction map 7 Asymmetric energy window clinical example with I-123 and Tc-99m 8 Clinical example - Tl-201 uniformity - Defective linearity correction 9 3

4 Uniformity Ga-67 Separate and sum of energy windows 10 Image without linearity or energy corrections 11 Side-by-side comparison with and without uniformity corrections 12 4

5 Fault energy correction map Clinical study 13 Loss of hermetic seal/optical coupling 14 Cracked crystal Puncture/impact 15 5

6 Cracked crystal Puncture/impact 16 Cracked crystal - Thermal 17 Crystal hydration 18 6

7 Crystal Irregularities 19 Uniformity Defective PM Tube 20 Uniformity Defective PM tube (newer digital camera) 21 7

8 Defective PMT at FoV edge 22 Clinical bone scan defective PM tube 23 Maladjusted PM tube 24 8

9 Unacceptable extrinsic floods Low energy collimator misalignment 25 Unacceptable extrinsic floods Low energy collimator angulation 26 Unacceptable extrinsic flood Collimator septa damage - Puncture 27 9

10 Clinical example Collimator star pattern 28 Fillable flood source - Air bubble 29 Fillable flood source - Non-uniform mixing 30 10

11 Fillable flood source bulging sides 31 Fillable flood source Adherence of activity to the container at the filling site (algae) 32 Non-Uniformity in Cobalt Sheet Source 33 11

12 Point Source Geometry and multihead systems 34 NEMA slit pattern Unacceptable difference in x and y spatial resolution 35 Intrinsic spatial resolution - Faulty linearity correction 36 12

13 Extrinsic Spatial Resolution - Moiré pattern 37 Uniformity and High Count Rates 38 Poor spatial resolution at high count rates due to misplaced events 39 13

14 SPECT Uniformity simulation with no noise Effect of projection sampling 40 Comparison of high and low count densities 41 Single head SPECT uniformity Ring artifact from real data 42 14

15 Dual head SPECT Clinical partial ring artifact 43 SPECT non-uniformity from high temperature 44 SPECT non-uniformity from outdated uniformity corrections 45 15

16 Myocardial Perfusion SPECT With and without uniformity defect 46 Center of Rotation (COR) Offset 47 Clinical SPECT brain perfusion Effect of COR offset 48 16

17 Effect of detector head tilt - Myocardial perfusion study 49 Effects of color table Myocardial perfusion 50 Whole body Scan Faulty PM tube old linearity and energy corrections 51 17

18 Whole body scan Co57 versus Tc-99m energy window 52 Whole Body Scan Contamination on handkerchief 53 Gated SPECT acquisition Problems due to heart arrhythmia 54 18

19 System uniformity Contaminated collimator 55 Positron range and image quality 56 PET detector failure 57 19

20 Controller board failure 58 Faulty timing calibration 59 Memory board failure 60 20

21 Normalization 61 Faulty normalization 62 Scatter correction artifact 63 21

22 Scatter correction artifact 64 Intravenous contrast artifact 65 Intravenous contrast artifacts 66 22

23 Breathing motion artifact 67 Subcutaneous tracer infiltration 68 Contamination at injection site 69 23

24 Contamination during flushing 70 Contamination post injection 71 Data entry errors and SUV analysis 72 24

25 Insufficient Bed Overlap 73 Thank you for your attention! References INTERNATIONAL ATOMIC ENERGY AGENCY, PET/CT Atlas on Quality Control and Image Artefacts, IAEA Human Health Series No. 27, IAEA, Vienna (2014). INTERNATIONAL ATOMIC ENERGY AGENCY, IAEA Quality Control Atlas for Scintillation Camera Systems, IAEA, Vienna (2003)