Optimizing CT Image Quality - Part 6 - Clinical Practice
This web-based training will look at CT dose in clinical practice – the expectations of dose delivery and dose reduction in adult vs. pediatric patient populations, the dose requirements for different examination types, and how the idea of dose in the US compares to other countries. The 30 minute presentation will review several dose reduction techniques and softwares, and will troubleshoot some common dose-related issues. Following the training, the user will demonstrate their acquired knowledge of these topics by completing a summary test. Upon successful completion of this assessment the learner will be eligible for 0.5 ASRT CEUs.
Expectations: Adults Expectations: Children Troubleshooting Optimizing CT Image Quality Clinical Practice Walter Huda, PhD Professor of Radiology Medical University of South Carolina Dose Savings Non-Contrast Contrast enhanced CT Angiography Small Moderate Large Adult Head Angiography 100 kV CTDIvol 15 mGy [S] Quality Reference mAs - 175 DLP 300 mGy-cm Effective Dose - 0.6 mSv Adult Abdomen (+ Contrast) 120 kV CTDIvol 12 mGy [L] Quality Reference mAs - 190 DLP 250 mGy-cm Effective Dose - 4 mSv CT Dose Comparison Head CT Dose Comparison by Country 1.9 mSv 1.8 mSv 1.8 mSv Abdomen/Pelvic CT Dose Comparison by Country 15 mSv 8.4 mSv 9.5 mSv Attenuation Based kV selection Anna Winklehner et al. Investigative Radiology 46 (2011) 767-773 Thoracoabdominal CTA CARE kV “On” kV used selected “by CARE kV” Topogram → Attenuation Info Tube Currents at Constant CNR Identical “Image Quality” Some kV Values Not Possible Select kV with Lowest Dose Body Mass Index (BMI) 75 kg & 1.73 m BMI = 25 kg/m2 Study Findings - 40 Patients 100 kv 58% 120 kV 36% Body CTA of the Aorta Reference kV - 120 kV Quality Reference mAs - 110 mAs CTDIvol - 10.6 mGy Body CTA of the Aorta + kV selection 100kV Effective mAs - 143 mAs CTDIvol - 6.4 mGy ↓ 40% Children should never be considered small adults! Yu et al., Mayo Clinic, Rochester MN 31 (2011) 835-848 Pediatric Abdominopelvic CTDIvol [L] 4 mGy CTDIvol [S] 8 mGy Dose Savings from kV Modification 5 year old [20 kg] Abdomen/Pelvic 120 kV ACR CT Ref Dose - CTDIvol [S] 20 mGy 100 kV Optimized - CTDIvol [S] 8 mGy kV Optimized Dose Savings - 60% Iso-center Improper Centering (Too High) AEC Assumes Patient is Large Improper Centering (Too Low) AEC Assumes Patient is Small Dose optimization slider is in correct position Soft Tissues (Non-contrast) CTA Check Reference Techniques kV and mAs Adult Head Reference Doses United States (American College of Radiology) - 75 mGy Britain (Health Protection Agency aka NRPB) - 65 mGy Adult Abdomen Reference Doses United States (American College of Radiology) - 25 mGy Britain (Health Protection Agency aka NRPB) - 14 mGy Check CARE Dose4D Curves Strength Size X-ray tube voltage (kV) selection Contrast medium and smaller patients - Lower kV Non-contrast medium and larger patients - Higher kV Imaging Task Low contrast - small dose reduction High contrast - larger dose reduction Troubleshooting Patient Positioning IQ Settings Ref. kV & Quality Ref. mAs CARE Dose4D Settings (Protocol)
- SOMATOM Definition ASmm
- SOMATOM Definition Flash
- SOMATOM Emotion
- SOMATOM Sensation
- SOMATOM Spirit