40TH ANNUAL MEETING. CTA Dose Reduction: Special Considerations in Children. Jeffrey C. Hellinger, MD FACC. October 13 16, 2012 Pasadena, CA

Size: px

Start display at page:

Download "40TH ANNUAL MEETING. CTA Dose Reduction: Special Considerations in Children. Jeffrey C. Hellinger, MD FACC. October 13 16, 2012 Pasadena, CA"

Corey Lloyd
5 years ago
Views:

1 40TH ANNUAL MEETING October 13 16, 2012 Pasadena, CA CTA Dose Reduction: Special Considerations in Children Jeffrey C. Hellinger, MD FACC New York Cardiovascular Institute Lenox Hill Radiology and Medical Imaging

2 40TH ANNUAL MEETING October 13 16, 2012 Pasadena, CA Disclosures Philips Healthcare TeraRecon Vital Images

3 Computed Tomographic Angiography Non-invasive High spatial resolution Robust, 3D and 4D imaging Fast, comprehensive cardiovascular imaging Ease of availability Ease of Patient Access Devices, stents, grafts

4 Computed Tomographic Angiography Radiation Exposure single multiple, cumulative Iodinated Contrast

5 Radiation Physics: Computed Tomography Image GENERATION: X-Ray beam attenuation within the body X-Ray beam REQUIRE sufficient Energy and Intensity Energy (voltage, kvp) determines the ability to penetrate and ionize tissues (e.g. deposit energy) Intensity (current, ma; exposure time; kvp) determines the number of photons in the beam (Signal Intensity vs Noise) Coverage TIME

6 Radiation Physics: CT Image Quality Number of X-Ray photons Signal intensity, direct relationship Noise, indirect relationship SNR N N N NOISE 1 N CNR = contrast to noise ratio (quantify image quality CNR = SHU 1 BgHU 2 N

7 Radiation Physics: CT Noise Determinants Number of Photons per voxel (indirect) Indirect relationships slice thickness (trade off for resolution) Field of view kvp mas Application: Increasing kvp, mas improves image quality, at the expense of increased radiation exposure

8 Core Radiation Reduction Strategies Appropriate indications Appropriate coverage Lowest possible kvp Lowest possible mas Fastest possible gantry rotation High-pitch spiral imaging

9 CTA: Appropriate Indications

10 Pediatric 64 channel single source MDCT ECG-Gated Cardic CTA: N=85 30 Histogram msv: 4.9 (with age weighting Factor) Frequency Arterial msv WITH Weighting Factor Hellinger et al, SPR 2010

11 18 Arterial msv WITH Weighting Factor Kvp Hellinger et al, SPR 2010

12 Effective mas Direct impact on msv Eff 1st pass mas Arterial msv WO Weighting Factor Kvp Hellinger et al, SPR 2010

13 Coverage (DLP) Direct impact on msv st Phase DLP Arterial msv WO Weighting Factor Kvp Hellinger et al, SPR 2010

14 10 y.o. Chest Pain msv=0.9

Congenital Lung CTA Low-dose CTA Chest CT P-value Male/Female 49/51 52/48 0.

15 Congenital Lung CTA Low-dose CTA Chest CT P-value Male/Female 49/51 52/ (%) Age at surgery (days) CCAM/hybrid 68% 72% 0.59 Patients studied

16 Congenital Lung CTA Low-dose CTA Chest CT P-value Radiation dose range (msv) Number of sequestrations missed * /114 3/103

17 Pediatric CVCT: Four Year Experience 118 (8%) 294 (19%) (4%) Neonates 1-12months Months >2 years

18 Pediatric CVCT: Neonates Congenital Lung Pulmonary Artery Thoracic Aorta PHTN Pulmonary Vein LE Renal Biphasic Abd TA_Aorta SVC Whole Body Head_Neck PE UE_LE

19 Pediatric CVCT: Neonates Avg msv = 1.64 (0.7) 2007 msv = msv = msv = 0.95

20 msv=3.2 msv=1.3 msv=0.5

21 msv = 0.77 (0.32)

22 msv = 0.28

23 msv = 0.21

24 Advanced Radiation Reduction Strategies Tube current modulation 70kV imaging Automated kv Increasing Detectors Leading to Volumetric Coverage Reduced mas Iterative Reconstruction Raw data domain Image domain Workstation image domain algorithms

28 Volumetric Whole Organ Imaging

29 Adenosine Rest-Stress CCTA

30 Adenosine Rest-Stress CCTA

31 Adenosine Rest-Stress CCTA

32 Volumetric Whole Organ Imaging msv = 3.5

33 Cardiovascular CTA Radiaton Exposure Acceptable Noise

35 Iterative Reconstruction

36 Iterative Reconstruction

37 Results SNR FBP AIDR FBP AIDR FBP AIDR Original 50% 75%

38 Results CNR FBP AIDR FBP AIDR FBP AIDR Original 50% 75%

39 Results Noise (SD) FBP AIDR FBP AIDR FBP AIDR Original 50% 75%

40 Chest CTA 34mAs DLP mSv 0.5mm images Original FBP Original AIDR

41 Chest CTA 34mAs DLP mSv 0.5mm images 50% Dose FBP 50% Dose AIDR (17mAs)

42 Chest CTA 34mAs DLP mSv 0.5mm images 75% Dose FBP 75% Dose AIDR (8.5mAs)

43 Workstation Image Domain Algorithms Typical Smoothing filter Boundary of area is also smoothed and decreases high contrast resolution Denoising Software CT number is smoothed, but the edge is enhanced, CT number Structural preservation and enhancement Improves Low Contrast Resolution and High Contrast Resolution Scanner and workstation options

44 3D Structural Preservation and Enhancement noise reduction increased CNR

45 3D Structural Preservation and Enhancement

46 Enhancement 3D Structural Preservation and Enhancement 10 y.o HTN Renal CTA msv = 0.6 (0.47) CNR = 4.4 CNR = 14

47 Enhancement 3D Structural Preservation and Enhancement 10 y.o HTN Renal CTA msv = 0.6 (0.47) CNR = 4.4 CNR = 14

48 3D Structural Preservation and Enhancement

49 3D Structural Preservation and Enhancement

50 3D Structural Preservation and Enhancement

51 Summary: CTA Dose Reduction Core Imaging Strategies Appropriate indications Appropriate coverage Lowest possible kvp Lowest possible mas Fastest possible gantry rotation time High-pitch spiral imaging

52 Summary: CTA Dose Reduction Advanced Imaging Strategies Tube current modulation 70kV imaging Automated kv Increasing Detectors (Leading to Volumetric Coverage) Iterative Reconstruction Raw data domanin Image domain Workstation image domain algorithms

53 Summary: CTA Dose Reduction All healthcare providers and parents play a role Education, protocols, and QA are essential Consider Study goals vs expected image quality. Maximize image quality at the lowest possible msv Continued technological advancements will require continuous quality assessment to modify protocols

54 40TH ANNUAL MEETING Thank you for your attention! October 13 16, 2012 Pasadena, CA

Patient radiation dose and image quality optimization in CT. Optimiser la dose patient et la qualité image en scanner

Conférence SPIMED - 8 juin 2012 IQ Patient safety Dose Reduction Patient radiation dose and image quality optimization in CT Optimiser la dose patient et la qualité image en scanner Philippe Coulon, PhD.