CGDent Dental Radiography & IRMER 2017 Exam Summary

1. UK Legal Framework for Dental Radiology

Dental radiography in the UK is governed by two separate pieces of legislation:

• IRR17 (Ionising Radiations Regulations 2017): Focuses on worker and public safety, equipment safety, and dosage limits.
• IRMER 2017 (Ionising Radiation (Medical Exposure) Regulations 2017): Focuses on patient protection, justification, authorization, and clinical evaluation.

2. IRMER 2017 Legal Roles

IRMER defines four distinct duty holders in dental practice:

1. Employer: Provides written Employer's Procedures, establishes quality assurance programs, and appoints the Medical Physics Expert (MPE).
2. Referrer: A registered healthcare professional who supplies clinical information to justify the exposure (e.g., Dentist).
3. Practitioner: Takes legal responsibility for justifying the individual exposure after balancing clinical benefit against radiation risk.
4. Operator: Carries out any practical aspect of the exposure (e.g., positioning film, pressing exposure button, processing image).

3. Radiation Protection Principles (ALARP)

All medical exposures must be kept ALARP (As Low As Reasonably Practicable) through:

• Rectangular collimation (reduces radiation area by 50% compared to round collimators).
• F-speed film or digital sensors.
• Minimum focus-to-skin distance of 200 mm for equipment operating above 60 kV.

4. CGDent Quality Assurance & Grading

Under CGDent guidance, radiographs are audited and graded:

• Grade 1 (Excellent): No anatomical or processing errors.
• Grade 2 (Diagnostically Acceptable): Minor errors that do not impair diagnostic utility.
• Grade 3 (Unacceptable): Errors render image diagnostically useless (e.g., cone cutting, extreme elongation).

Targets: At least 70% of radiographs must be Grade 1, and no more than 10% should be Grade 3.