Performance Assessment / Quality Assurance in Cross Sectional Modalities

Performance Assessment / Quality Assurance in Cross Sectional Modalities

Module Learning Objectives

• Physical Principles of Imaging Modalities
  • Understand and explain the fundamental physics that inform cross-sectional imaging technology designs and operational parameters.
• Quality Assurance and Control
  • Assess the operational acceptability of imaging equipment through various quality assurance (QA), quality control (QC), and radiation dosimetry tests.
• Hazards and Errors
  • Identify potential hazards and errors within the imaging environment (both system-related and human-errors), explore their causes, and propose methods to address them.

Session Learning Objectives

• Knowledge of QA Procedures
  • Familiarity with QA documents and testing procedures for Ultrasound, CT, and MRI.
• Relevance of QA in Clinical Practice
  • Understand how QA procedures impact daily clinical operations.

General Principles of Quality Assurance

• Determine the clinical suitability of the imaging system's performance.
• Monitor system performance changes over time.
• Implement standardized testing protocols and criteria.
• Follow guidance from professional regulatory bodies.

UK Guidance Documents

• Ultrasound: IPEM Report 102 & BMUS QA Guidelines.
• CT: IPEM Report 91 & IPEM Report 32, focusing on Levels A & B tests.
• MRI: IPEM Report 112 (emphasis on user tests).

Types of QA Tests for Ultrasound

1. Routine Inspection
   • Check in-air reverberation patterns for defects.
   • Identify artifacts like image dropout linked to transducer issues.
2. Damage to Acoustic Array
   • Damage causes hypo-echoic artifacts due to trauma to the acoustic array (e.g., dropping the transducer).
   • Acoustic arrays are fragile (only ~0.5 mm thick) and can shatter easily.
3. Cable Damage Assessment
   • Problems like streaks on images may arise from damaged cables due to improper storage.
4. Delamination
   • Inspect for artifacts caused by probe degradation affecting reverberation images.

BMUS QA Guidance Levels

• Level 1: Infection Control & Scanner Damage
  • Regular cleaning and inspection, ensuring operational integrity and preventing risks.
• Level 2: Basic Scanner & Transducer Testing
  • Daily performance evaluations without sophisticated equipment.
• Level 3: Advanced Evaluation
  • Simplified additional testing to identify scanner faults performed monthly.

Level 1 Tests (Daily & Weekly)

• Clean transducer, cables, and console after every use.
• Inspect transducer and cables for visible damage.
• Verify operation of controls and brake/wheel functions.

Level 2 Tests (Daily & Monthly)

• Check monitor contrast, brightness, and greyscale displays.
• Assess air reverberation patterns and electronic noise thresholds monthly.

Ultrasound Summary

• Visual inspections can reveal ~90% of faults; use in-air reverberation patterns for sensitivity and noise testing.