Optimisation and Diagnostic Reference Levels (DRLs)

Optimisation

Optimisation means ensuring the dose delivered to the patient is the lowest necessary to get the desired radiographic information.

IRMER17 places the responsibility for ensuring patient doses are optimised on the practitioner (who justifies the exposure, usually the dentist) and the operator (who undertakes the exposure, usually the dentist or qualified dental nurse).

To ensure an exposure is optimised, consideration must be given to multiple factors. These include:

• Selection of the most appropriate X-ray equipment for the clinical task
• Selection of the correct X-ray beam collimation
• Correct selection of exposure parameters
• Correct radiographic technique.
• Correct patient positioning
• Ensuring correct image processing techniques are used
• Training of staff in correct radiographic techniques
• Consultation with the MPE

Diagnostic Reference Levels (DRLs)

A DRL is an aid to the optimisation of patient dose and is defined in IRMER17 as a level of patient dose for a typical examination of a group of standard-sized individuals for broadly defined types of equipment.

IRMER17 requires the dental practice to set DRLs for local use, in consultation with its MPE, for each type of dental radiography in use at the practice, and for both adults and children (if relevant).

Local DRLs should be set at values no higher than the prevailing national DRLs published by PHE. These national DRLs, which are updated every few years, are based on UK-wide patient dose surveys. The current values can be found here.

Patient doses should be reviewed regularly against local DRLs with assistance from the MPE. This should happen whenever a routine performance test is carried out for an X-ray set and whenever new equipment is installed, which could be a new X-ray set or a new imaging system, such as changing from film to a digital system.

Where patient doses consistently exceed the local DRLs, a review of radiographic practices should be carried out with the MPE. The objective of such a review is to identify the underlying reasons for the higher doses and then to either improve radiographic technique or justify the use of continued techniques.