Ionising Radiation
What this domain tests
This domain covers Irish radiation protection law, including SI No. 256 of 2018, EPA registration of dental X-ray equipment and the Dental Council radiation protection guidance. It tests justification, optimisation, dose limitation, quality assurance and record-keeping.
Core rules and concepts
- Every exposure must be justified clinically; routine radiographs without a patient-specific indication are not acceptable.
- Optimise technique: rectangular collimation, appropriate receptor, correct exposure factors, good positioning and avoidance of retakes.
- Apply ALARA. Dose limits apply to occupational and public exposure, not to the patient's diagnostic exposure, which must still be justified and optimised.
- The practitioner and referrer share responsibilities; staff must have appropriate training and equipment must be registered and quality-assured.
- Record the justification, the radiograph taken, the findings and any repeat exposure.
Worked example
A patient attends with acute pain and swelling associated with a lower molar. A periapical radiograph is justified to assess the apex and root morphology before treatment. You use a digital receptor with rectangular collimation, position accurately, avoid a repeat, and record the indication and findings. A routine OPG for a asymptomatic patient with no clinical indication would not be justified.
Traps that cost marks
Taking radiographs for defensive or administrative reasons; failing to record justification; using the same exposure settings for every patient; repeating a film without assessing why; ignoring pregnancy questions when a justified exposure is being planned; neglecting equipment QA or registration.