Dose assessment in the management of patient protection in diagnostic and interventional radiology

The increasingly widespread use of x-rays in diagnostic and interventional radiology provides not only enormous benefits to patients, but also significant radiation exposure for populations. The protection of patients against potential radiation harm requires the elimination of all unnecessary and unintended x-ray exposure in relation to effective clinical diagnosis. Dosimetry is an essential management tool for patient safety by allowing the assessment of typical radiation risks in support of the justification of procedures, and the routine monitoring and comparison of typical doses in pursuit of the optimization of patient protection. Periodic assessment of patient doses should form an integral part of quality assurance in x-ray facilities and is best based on practical measurements that provide useful characterization of patient exposure, such as entrance surface dose, dose-area product and, for CT, weighted CT dose index and dose-length product. In addition, the monitoring of cumulative dose during complex interventional procedures underpins the effective management of potential tissue reactions. Mean values determined for practical dose monitoring quantities in a facility for each type of procedure and patient group can form the basis not only for estimates of typical organ and effective doses utilizing appropriate coefficients, but also local diagnostic reference levels (DRLs). DRLs represent a pragmatic mechanism for promoting continuing improvement in performance by facilitating comparison with national values and practice elsewhere. The application of DRLs in the UK over the last 25 years, within a coherent framework for patient protection, has successfully helped to reduce unnecessary exposures, with national DRLs for many procedures falling by a factor of two.