Pergascript orange-based polymeric solution as a dosimeter for radiotherapy dosimetric validation.

Abstract

A radiation colour former amino fluoran dye, Pergascript Orange (PGO), in a polyvinyl butyral solution containing a colour developer, hexachloroethane (HCE), was prepared and investigated for radiotherapy dosimetry of 60Co, 6\u202fMV and 15\u202fMV photons. PGO, a colourless dye, reacts with the acid produced upon radiation exposure of HCE, enabling the lactone ring to open and the orange colour of PGO to develop. The ring opening of PGO was confirmed by the appearance of a broad peak of OH- at 3360\u202fcm-1, CO carboxylic peak at 1763\u202fcm-1, and an iminium group peak at 1640\u202fcm-1. The dose response of all prepared compositions was linear in the dose range of 1-20\u202fGy. Increasing HCE in the dosimeter matrix from 63\u202fmM to 106\u202fmM enhanced the radiation sensitivity by ≈58%. The radiation sensitivity of PGO-PVB (PGO-P) dosimeter is comparable with Fricke gel and higher than N-(Isobutoxymethyl) acrylamide polymer gel dosimeters. The experimental results reveal an energy-independent response (≈1.2% variation at 1σ) in the studied range of radiotherapy beam quality from 60Co beams to the beams from Linacs with a maximum energy of 15\u202fMeV. Based on the theoretical study, this dosimeter is water equivalent from 80\u202fkeV to 10\u202fMeV. The overall uncertainty was found to be 4.5% at the 95% confidence level, indicating the possibility of using PGO-P dosimeter in conventional radiotherapy dose verification.