The impact of external dosimetry verification in radiotherapy

Abstract

The value of independent dosimetry audit is now better recognised and has become well documented. From the excellent work of the IAEA and national standards labs in reference dosimetry audit through to end-to-end measurements which follow the commissioning of a new advanced radiotherapy technique, there is no doubt that the quality of radiotherapy has improved over recent decades, and that audit has played a role in this. These independent audits increase the confidence in delivery as well as creating the data which allow centres to benchmark themselves against others and thus know whether they have got the best out of a system. This process also improves standards by identifying outliers and providing support to help them improve. However the impact of dosimetry audit also extends further. A survey in the UK on quality assurance procedures for IMRT, suggested that audit increases confidence and therefore helps to support the reduction of measurement based QA which is done on a per patient basis. There is also increasing evidence that dosimetry audit has an impact on improving clinical outcomes. Additionally the robust approach of external beam audit has been taken up in brachytherapy and an increasing number of dosimetry audits are now taking place for source based therapy. Furthermore the experience in therapy audit is helping to guide the development of quality assurance in pre-clinical work, thus ensuring true end to end dosimetry verification from the laboratory to the clinic.