DOSIMETRIC CHARACTERIZATION OF CUSTOMIZED PLA PHANTOM FOR RADIOTHERAPY

The purpose of this study was to assess the dosimetric properties of PLA (polylactic acid) phantom in comparison to solid water phantom for photon and electron beam radiotherapy. The standard solid water and PLA phantom were characterized for their uniformity and Hounsfield Unit (HU) using SOMATOM computed tomography (CT) scanner. Ionization chamber and Gafchromic EBT3 films were used to measure the dose delivered at the depth of maximum dose in the solid water and PLA phantom. The dose prescribed during the irradiation with photon and electron beams were set from 50 to 1000 cGy. The results show the percentage dose difference measured using ionization chamber for 6 and 10 MV photon beams between solid water and PLA phantom was less than ± 4%. Meanwhile, for 6 and 12 MeV electron beams, the percentage dose differences measured for both phantoms was within ±2%. Measurement using Gafchromic EBT3 films also agreed with ionization chamber results with percentage dose differences between solid water and PLA phantom less than ± 4%. In conclusion, the PLA phantom could potentially be applied for routine quality assurance check and dosimetry confirmation in radiotherapy as an alternative to standard solid water phantom.