PEPconnect

Optimizing CT Image Quality - Part 5 - Clinical Techniques

This web-based training will offer Radiologic Technologists valuable recommendations on how to balance CT technical parameters within the physical constraints of scanner tube capacities. The 30 minute presentation will discuss kV, mAs, and scan time as they relate to patient size, examination requirements and hardware limitations. Also discussed are Siemens’ proprietary software features CARE Profile curve, Scan Assistant and FAST Adjust. Following the training, the user will demonstrate their acquiredknowledge of these topics by completing a summary test. Upon successful completion of this assessment the learner will be eligible for 0.5 ASRT CEUs.

Constraints Tube Loading Overcoming Tube Limitations Optimizing CT Image Quality Clinical Techniques     Walter Huda, PhD Professor of Radiology Medical University of South Carolina   Image Quality → Multi-Dimensional Factors to consider Min./Max. kV Total scan time Avoid Low kV in Head CT Avoid High kV in CTA Max scan time Optimal kV ↓ Reduce when putting iodine in patient Reduce when scanning smaller patients ↑ Effective mAs [mA x s] / Pitch [mA x s] / Pitch High tube current Reduce tube rotation time or pitch (increases scan time) [mA x s] / Pitch CTDIvol per 100 Effective mAs 5.7 mGy (120 kV) 3.3 mGy (100 kV) 1.5 mGy (80 kV) 25kg Pediatric Patient - CTDIvol = 6 mGy 105 Eff. mAs (120 kV) 180 Eff. mAs (100 kV) 408 Eff. mAs (80 kV) 30 cm scan CAP (0.33 s) 80 kV - Pitch 0.4 → 12.9 s 100 kV - Pitch 0.9 → 5.7 s 120 kV - Pitch 1.4 → 3.7 s Operator Can Set Limits Min & Max kV Max Scan Time Scan Protocol Assistant [Application Specialist] Power in: 100 kW (100K J per second) Anode Storage - 5MJ Cooling: 10 kW Cooling: 60 kW X-ray Tube Heating ↑ Scan time (↓ Pitch) ↓ Max mAs CARE Profile Min mA (green) Max mA (yellow) mA profile CARE Profile Patterns Spiral HR/2D Sequence Cardiac Colors and Patterns Green Green/ Some Yellow Green/ Yellow Yellow Green Profile: No Problems Green Striped Peak: Exceeds System Limits   ↓ Image Quality Acceptable Yellow Peak: Exceeds System Limits   ↓ Image Quality Corrective Action? Yellow Profile: Exceeds System Limits   Corrective Action Required Adjustable Parameters Scan Time & Pitch Max mAs Yellow Peak: Corrective Action Recommended or Required ← → ← Shortest Acceptable Scan Time ← Highest Acceptable Pitch Scan Protocol Assistant (Application Specialist) Low Effective mAs Long Scan Time ← Maxium Reduction in Effective mAs (25%) ← Shortest Acceptable Scan Time ← Highest Acceptable Pitch Constraints Minimum kV Maximum kV Total scan time Tube loading CARE Profile Displays Overcoming tube limitations Scan Time Pitch Maximum mAs

  • SOMATOM Definition ASmm
  • SOMATOM Definition Flash
  • SOMATOM Emotion
  • SOMATOM Sensation
  • SOMATOM Spirit