To prevent errors in dosimetry from causing radiation injuries, the Dosimetry Laboratory performs a follow-up procedure if the TLD identifies errors. When a TLD audit detects discrepancies, the centre is alerted accordingly, and asked to repeat the test. If the second TLD audit does not show good results, the follow-up programme ensures the hospital knows how to fix the problem and can do so effectively. Targeted expert missions and more comprehensive medical physics reviews can also be provided upon request to address cases of non-compliance that might be revealed by a TLD audit process.
Medical physicists performing TLD dose measurement. (Photo from IAEA TLD irradiation video tutorial, E. Izewski, IAEA)
Since it became operational, the IAEA/WHO TLD audit programme has revealed a large number of poorly calibrated radiation sources. The records of TLD audit results have been showing a steady increase in hospitals' abilities to get the dose right. More and more low and middle income countries now possess radiation oncology clinics. Most of the over 12,000 radiotherapy beams checked since the inception of the IAEA/WHO TLD programme have been in these low and middle income countries. Since these countries may not be able to afford establishing and maintaining a national audit system, the IAEA/ WHO TLD audit programme offers them this service. Without TLD audits, the concerned Member States would not be able to guarantee accurate calibration of their radiotherapy facilities.
The IAEA/WHO TLD audit service has contributed to improvements in the quality of radiotherapy dosimetry practices worldwide. In over 2,200 radiation oncology clinics in 132 countries that use the TLD service, both clinicians and patients can trust that the radiation beam calibration is correct, leading to reliable and effective treatment.