DRL as a level used in medical imaging to indicate whether, in routine conditions, the dose to the patient or the amount of radiopharmaceuticals administered in a specified radiological procedure for medical imaging is unusually high or unusually low for that procedure.?

Diagnostic reference levels (DRLs) are a practical tool to promote optimization. DRLs were first successfully implemented in relation to conventional radiography in the 1980s and subsequently developed for other modalities in the 1990s. ?

It is important to recognize that DRLs are one of the steps in the overall process of optimization. DRLs are general guideline for clinical operations and do not apply directly to individual patients and examinations.?