Optimizing CT Image Quality - Part 3 - CARE Dose 4D

Optimizing CT Image Quality CARE Dose 4D     Walter Huda, PhD Professor of Radiology Medical University of South Carolina   Automatic Exposure Control Quality Reference mAs Modulation Strength → → Constant Image Receptor Dose X-ray AEC ensures Consistent Image Quality kV selected by operator mAs Adjusted (Patient Size) How Much Radiation Should Be Used? mAs → Receptor Dose = 5 µGy   Set ~ 120 kV 200 mA 5 ms Receptor Dose → 5 µGy 1 mAs CARE Dose4D ↑ mA for  ↑ thickness ↓ mA for  ↓ thickness Adjust mA along patient Adjusts Effective mAs Between Patients Larger patient  → more radiation Smaller patient  → less radiation Child  → much less radiation Tube modulation Uniform “Dose” ↓ "Dose" ↑ X-ray Efficiency   CTDIvol Quality Reference mAs Never changed for “a patient” Body Region Diagnostic Task Radiologist Preference Standard Adult Patient syngo CT 2011 A Siemens Protocols 120 kV   CTDIvol (Eff mAs)   Scan Length (DLP)   Effective Dose Head CTDIvol is 60 mGy [S] [Effective mAs is 390]   17 cm scan (DLP 1000 mGy-cm)   Effective Dose 2 mSv Chest CTDIvol is 7.4 mGy [L] [Effective mAs is 110]   30 cm scan (DLP 220 mGy-cm)   Effective Dose 4.5 mSv Abdomen CTDIvol is 14 mGy [L] [Effective mAs is 210]   25 cm scan (DLP 350 mGy-cm)   Effective Dose 5.7 mSv Pelvis CTDIvol is 14 mGy [L]] [Effective mAs is 210]   30 cm scan (DLP 420 mGy-cm)   Effective Dose 6 mSv Type of Examination 12 Specified Body Regions Select Quality Reference mAs for each Never changed for a patient syngo CT 2010 or older FAST CARE syngo CT 2011 Very weak Weak Average Strong Very strong   Normal Adult Body     Average: 100%     Large Adult Body   Very weak: 130% Weak: 140%  Average: 160% Strong: 180% Very strong: 220%    Small Patients ≠ Obese Patients Small - Very Weak Obese - Very Strong Small Adult Body   Very weak: 80% Weak: 70%  Average: 60% Strong: 50% Very strong: 45%      Very small adult: 40%   Small adult: 60% 75 kg adult: 100%   Large adult: 160%   Very large adult: 220%   Obese adult: 300% Patient Age (Pediatric) Quality Ref mAs (75 kg) Pediatric Head   Newborn: 75% 2 year old: 85% 6 year old: 95% Pediatric Body   Newborn: 40% 1 year old: 50% 5 year old: 60% 10 year old: 70% Very Weak | Weak | Average | Strong | Very Strong Automatic Exposure Control mA is varied: Around the Patient - Along the Patient - Between Patients Quality Reference mAs set once in the protocol for average adult 12 Body Regions Diagnostic Task Radiologists CTDIvol Modulation Strength Five "strengths" - very weak to very strong