A Malaysian Secondary Standard Dosimetry Laboratory participation in the IAEA/WHO Postal Dose Quality Audit: Data Analysis 2009 – 2019

Participation of Secondary Standard Dosimetry Laboratory (SSDL) of Malaysia in the IAEA/WHO Postal Dose Quality Audit Service is very important in confirming the traceability of absorbed dose measurements provided to the radiotherapy centres. In the audit, the SSDL was supplied with a set of dosimeter for irradiation with absorbed dose to water of 200 cGy in reference conditions using ⁶⁰Co teletherapy or medical linear accelerator. In the period of 2009 to 2019, a total of 10 photon beams from ⁶⁰Co teletherapy unit, 6 MV X-ray and 10 MV X-ray produced by medical linear accelerator have been audited. The results of the audit demonstrate that the mean of percentage deviations between the SSDL and the IAEA measurements was -0.35% with standard deviation of 0.86%. The deviations vary between a minimum percentage relative deviation of -2.5% and a maximum of 0.6%. These results were considered satisfactory in which complied with the IAEA's acceptance limit of ± 3.5%.