Radiation Safety, Imaging and Quality Governance
This domain tests radiation physics, dose monitoring and optimisation, imaging selection and quality governance. Expect dose-limit calculations and ALARA decisions.
Core rules
- Dose metrics: dose–area product reflects total radiation burden; peak skin dose reflects local skin risk. Record both for complex procedures.
- Deterministic effects: early transient erythema around 2 Gy; main erythema around 6 Gy; ulceration and necrosis at higher doses. Stochastic effects have no threshold.
- Occupational limits: effective dose 20 mSv/year averaged over five years; eye lens 20 mSv/year; skin and extremities 500 mSv/year.
- Optimisation: pulsed fluoroscopy, collimation, last-image hold, avoiding magnification, increasing distance from the tube, and using the inverse-square law.
- Quality: audit, morbidity and mortality review, WHO surgical safety checklist and informed consent.
Worked example
A complex embolisation records an air kerma of 4 Gy at the reference point. Reasoning: this exceeds the threshold for deterministic skin effects. Document the dose, inform the patient, arrange skin follow-up, and review the procedure for avoidable fluoroscopy time.
Traps
Confusing dose–area product with peak skin dose; failing to record dose; ignoring eye-lens dose; using magnification unnecessarily; omitting dose from the consent discussion for long procedures.