(1715) Optimization of technique
Circumstances where significantly different doses or beam qualities are employed for the same technique/examination type may give rise to substantially different dose distributions. Hence effective dose would seem to be a relevant quantity for comparison.
DRL’s are considered to be a modality-specific dose quantity for identifying the dose that is acceptable for a satisfactory level of image quality. However, the value of DRL’s in the application of optimization strategies, when a degree of optimization has already taken place has been questioned (Sutton et al, BJR , 2014, Rehani, BJR, 2015) and alternative approaches suggested.
Under such circumstances the effective dose would seem to be an ideal risk related performance indicator to assess the optimisation of similar techniques applied in the same or different departments when measured doses are routinely below any appropriate DRL. Equally when DRL’s are expressed in a variety of different quantities (DLP. DAP. ESD etc) effective dose provides a common basis for comparison of risk related performance. A reduction of risk would then be the driving force for improvement rather than attempting to reduce a DRL, which can be inconclusive.
The collective effective doses, for patients who undergo the same or different types of examinations, provide an index of relative-risk management and thus radiation protection performance at any site. The average effective dose per patient for specific patient groups (age, sex, weight) for individual or multiple types of examination could then provide a suitable basis for comparison when different frequencies of examinations occur. Such a relative risk index should not be dependent upon the dose-response model employed unless it is used to assess lifetime excess cancer risks.