24 Questions
What is the acceptable range for the CT number of water in a uniform water phantom?
0 ± 4 HU
What is the maximum deviation allowed for X-ray tube voltage in digital X-ray equipment?
10%
What is the minimum focal spot-to-skin distance required for stationary fluoroscopic equipment?
38 cm
Which of the following is NOT a common equipment used in QC and QA tests?
Defibrillator
What is the recommended frequency for performing a CT Checklist?
Monthly
Which of the following is an example of a quality control record sheet?
Siemens Somatom weekly QA record sheet
What is the purpose of a test pattern image in quality control tests?
To assess image resolution and quality
What is the primary objective of quality assurance in medical imaging?
To enhance patient care and departmental policies
What is the primary goal of quality control tests in medical imaging?
To optimize image quality
Which of the following is NOT a objective of quality control in medical imaging?
To improve image interpretation and report availability
What is the purpose of acceptance testing in medical imaging?
To ensure new equipment meets specified performance standards and regulatory requirements
Which of the following is a step in the acceptance testing process?
Verification of manufacturer's performance specifications
What is the primary focus of quality control tests in medical imaging?
Monitoring and maintaining technical elements of the system
Which of the following is a benefit of baseline data collection in acceptance testing?
Establishing a reference point for future quality control
What is the primary goal of safety checks in acceptance testing?
To confirm the equipment operates safely for patients and operators
Which of the following is NOT a objective of quality assurance in medical imaging?
To ensure instrumentation and equipment are functioning correctly
What is the primary purpose of performing daily QC tests on X-ray equipment?
To maintain optimal image quality
Which of the following is NOT a component to be inspected during daily QC tests in mammography?
Patient examination table
What is the primary goal of assessing the performance of electronic display devices in medical imaging systems?
To detect artifacts and assess image quality
What is the term used to describe the defined range of values within which radiological imaging parameters must fall to ensure correct equipment function and high-quality images?
Acceptable limits
Which of the following is an example of variation in X-ray equipment?
Deviation from acceptable limits
What is the purpose of using test patterns, such as the SMPTE or TG18-QC, in medical imaging system quality control?
To detect artifacts and assess image quality
In which type of medical imaging system is it essential to verify the motion of the X-ray tube assembly during daily QC tests?
Radioscopic systems
Why is it important to adhere to local guidelines and regulations in medical imaging system quality control?
To comply with regulatory standards
Study Notes
CT Number Accuracy
- The mean CT number of water must be in the range of 0 ± 4HU.
- The standard deviation of the CT number of water must remain within established baseline and acceptable limits of variation.
Accuracy of Loading Factors
- Loading factors must not deviate from the selected factors by more than:
- 10% for X-ray tube voltage
- (10% + 1 ms) for loading time
- 20% for X-ray tube current
- (10% + 0.2 mAs) for current-time product
Focal Spot-to-Skin Distance
- Mobile equipment: the focal spot to skin distance must not be less than 30 cm.
- Stationary equipment: the focal spot to skin distance must not be less than 38 cm.
Quality Control Tests
- Examples of common equipment used in QC and QA tests:
- Checklist
- Phantom (if advised by the manufacturer)
- Test Pattern Image (e.g., SMPTE or TG18-QC)
Checklist
- CT Checklist: performed monthly
- Mammography Checklist: performed daily
- Daily QC tests:
- System movement
- Overall visual assessment of electronic display devices (using SMPTE or TG18-QC test patterns)
Acceptable Limits
- Defined range of values within which radiological imaging parameters must fall to ensure equipment is functioning correctly and producing high-quality images.
- Established based on regulatory standards, guidelines, and best practices to ensure patient safety, diagnostic accuracy, and consistency of imaging results.
Quality Assurance (QA) and Quality Control (QC)
- QA objectives:
- Enhance patient care
- Implement management techniques
- Develop departmental policies
- Ensure technical effectiveness and efficiency
- Provide in-service education
- Ensure timely report availability
- QC objectives:
- Deal with technical factors that contribute to image quality
- Monitor and maintain technical elements of the system
- Instrumentation and equipment
Acceptance Testing
- Verification of specifications: ensuring equipment meets manufacturer's performance standards.
- Safety checks: confirming equipment operates safely for patients and operators.
- Regulatory compliance: ensuring equipment complies with relevant regulatory standards and guidelines.
- Baseline data collection: establishing baseline performance data for future reference and ongoing quality control.
This quiz tests your understanding of the accuracy requirements for CT numbers and loading factors in digital X-ray and CT scans. It covers the acceptable limits of variation for CT numbers, loading factors, and their associated tolerances.
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