The IAEA/WHO TLD postal programme for radiotherapy hospitals.

BACKGROUND AND PURPOSE Since 1969 the International Atomic Energy Agency (IAEA), together with the World Health Organization (WHO), has performed postal TLD audits to verify the calibration of radiotherapy beams in developing countries. MATERIALS AND METHODS A number of changes have recently been implemented to improve the efficiency of the IAEA/WHO TLD programme. The IAEA has increased the number of participants and reduced significantly the total turn-around time to provide results to the hospitals within the shortest possible time following the TLD irradiations. The IAEA has established a regular follow-up programme for hospitals with results outside acceptance limits of +/- 5%. RESULTS The IAEA has, over 30 years, verified the calibration of more than 3300 clinical photon beams at approximately 1000 radiotherapy hospitals. Only 65% of those hospitals who receive TLDs for the first time have results within the acceptance limits, while more than 80% of the users that have benefited from a previous TLD audit are successful. The experience of the IAEA in TLD audits has been transferred to the national level. The IAEA offers a standardized TLD methodology, provides guidelines and gives technical back-up to the national TLD networks. CONCLUSION The unsatisfactory status of the dosimetry for radiotherapy, as noted in the past, is gradually improving; however, the dosimetry practices in many hospitals in developing countries need to be revised in order to reach adequate conformity to hospitals that perform modern radiotherapy in Europe, USA and Australia.