Multicentre dose audit for clinical trials of radiation therapy in Asia

A dose audit of 16 facilities in 11 countries has been performed within the framework of the Forum for NuclearCooperation in Asia (FNCA) quality assurance program. The quality of radiation dosimetry varies because ofthe large variation in radiation therapy among the participating countries. One of the most important aspectsof international multicentre clinical trials is uniformity of absolute dose between centres. The National Instituteof Radiological Sciences (NIRS) in Japan has conducted a dose audit of participating countries since 2006 byusing radiophotoluminescent glass dosimeters (RGDs). RGDs have been successfully applied to a domestic postaldose audit in Japan. The authors used the same audit system to perform a dose audit of the FNCA countries.The average and standard deviation of the relative deviation between the measured and intended dose among46 beams was 0.4% and 1.5% (k = 1), respectively. This is an excellent level of uniformity for the multicountrydata. However, of the 46 beams measured, a single beam exceeded the permitted tolerance level of ±5%. Weinvestigated the cause for this and solved the problem. This event highlights the importance of external audits inradiation therapy