Optimizing CT Image Quality: Clinical Techniques

November 2011 PART 5: CLINICAL TECHNIQUES CONSTRAINTS Constraints Tube Loading Image Quality Overcoming  Tube Limitations Multi-Dimensional Factors to consider Avoid Low kV in Head CT Min./Max. kV Beam Hardening Artifact Total scan time Avoid High kV in CTA Max scan time Part 5 (Clinical Techniques) Huda 1 November 2011 Optimal kV  CTDIvol per 100 Eff. mAs  Definition  Effective mAs 1.5 mGy (80 kV) [mA x s]/Pitch 3.3 mGy (100 kV)  Scan Times 5.7 mGy (120 kV) CTDIvol = 6 mGy 30 cm scan CAP (0.33 s) 408 Eff. mAs (80 kV) At 80 kV Pitch 0.4  12.9 s 180 Eff. mAs (100 kV) At 100 kV Pitch 0.9  5.7 s 105 Eff. mAs (120 kV) 120 kV Pitch 1.4  3.7 s Operator Can Set “Limits” TUBE LOADING Min & Max kV Power ~ 100 kW Max Scan Time Scan Protocol Assistant [Application Specialist] Part 5 (Clinical Techniques) Huda 2 November 2011 Power In: 100 kW X-ray Tube Heating Scan Time Cooling & Pitch Max mAs Energy In Anodo pu)) Cooling: 10 kW Cooling: 60 kW 40 - Time (minutes) Anode Storage 5 MJ Left of Topogram display of: CARE Profile Examination Consguration Min mA Workflow Topogrom Processing Contrast 10.10.02-14:33:03-DST-Specials ... :10.10.02-14:33:03-DST-1.3.1 ... SOMATOM Definition Display Opeices +18-Nov-1858, 0, 151Y CARE DOSNO configuration mAs adhocation to porient site 02.01 2010 CARL PYOtie - :14:30:30.66 (green) Exposed range La WyMk Dese Repen Shoulder This - Activete Dose Report : Auto yansfer Abdomen Max mA Additional transfer None - (yellow) Dose Alert Adult Child Vaoou ar Buty - CTDIVCI moy Curde Voy Anup DUP moycm Fongiralary OK Duta/t Setings Holp 512 010 ETzor UOPO leva mA profile CARE Profile Patterns CARE Profile Displays Colors & Patterns Spiral HR / 2D Sequence Cardiac Part 5 (Clinical Techniques) Huda 3 November 2011 Green Profile  No Problems! Green Striped Peak: Exceeds System Limits a1 0.62 14 35 03 DSY Specials . SOMATON DemBonF  Image Quality “Acceptable” 512 0/0 - T2Of UOPO 1eva W 350 Barely! Yellow Peak: Yellow Profile: Exceeds Systems Limits Exceeds System Limits  Image 3-DST-Special 10.10.02-14:33:03-DST-Specials 10.10.32-14:33:03-D31-1.3.1 .. :"13-Nov-1858 D 151Y 114:33:38.00 Quality Corrective Action? TIG.3 Considerably! Action required OVERCOMING TUBE LIMITATIONS Yellow Peak: Corrective Action Recommended or Required Abdomenintervention (Adult) Adjustable Parameters Pause L4-5 Pause 15-31 Scan Time Pause (& Pitch) DAbdSeq Contrast Abdomen Max mAs Adjust load “Adjust” Part 5 (Clinical Techniques) Huda 4 November 2011 Thor Abd Scan Time Scan Pitch Max. mas Max. MAS Scan time 6.62 Original Value (Triangle) Pitch 1.4 Slider Displays Max mAs 203 Current Value 16.19 10.55 0.35 Scan Time Pitch .55 Shortest Acceptable Highest Acceptable Scan Time Pitch Scan Protocol Assistant Maximum Reduction [Application Specialist] in Eff. mAs (25%) Max. MAS 611 815 815 mAs Eff. mAs Scan Time Part 5 (Clinical Techniques) Huda 5 November 2011 Maximum Scan Time CLINICAL TECHNIQUES SUMMARY Scan Time 16.19 0.55 Tube Loading Constraints CARE Profile Displays Minimum kV ............ Maximum kV Total scan time A Overcoming tube limitations Next CLINICAL Scan Time PRACTICE 0 .35 Pitch Max. MAS 815 Scan Time CLINICAL & Pitch TECHNIQUES Max. mAs Part 5 (Clinical Techniques) Huda 6