Room: Karl Dean Ballroom A1
Purpose: This work presents an initial evaluation of a novel reusable radiochromic sheet, which has been developed for potential use as an economic film substitute and an in-vivo radiochromic bolus. The sheet is made from a new formulation of PresageÂ® (Heuris Inc.), with radiation-induced optical density (OD) change amenable to read-out with a commercial flat-bed optical scanner.
Methods: Basic radiochromic properties of the Presage-ReU sheet were characterized including temporal decay of OD, dose sensitivity and consistency with repeat irradiations, response uniformity, and temperature and beam energy dependence. An optimized readout procedure was devised including scanning time window. Temporal decay was evaluated by scanning sheets at multiple time-points post-irradiation. The dose sensitivity and energy dependence were tested by irradiating sheets to various doses at different energies and comparing the change in OD signal per unit dose. Memory effect from previous irradiations was investigated by irradiating the same sheet with increasing field sizes on subsequent days (after the prior irradiation had cleared). The thermal dependence at time of irradiation was investigated by submerging the sheets in different temperature water baths during irradiation, and tracking OD change.
Results: The radiation induced OD change in the sheets was found to decay to baseline within 24 hours, and a scanning time window of 0-24 minutes was identified, where the OD change is <3%. The sheets were not observed to carry a memory of previous irradiations within measurement uncertainty. Repeat irradiations showed consistent sensitivity (OD within 5%, tested for 6 irradiations). The sensitivity of the sheets was found to be slightly temperature-dependent, but remained within 3% for Â±2 degrees of skin temperature.
Conclusion: Presage-ReU shows promise as an economic multi-purpose alternative for film applications and as a radiochromic bolus. Further work is required to confirm inter-batch consistency, and to develop a softer material for bolus applications.
Funding Support, Disclosures, and Conflict of Interest: Research reported in this publication was supported by National Institutes of Health under award number 1R41CA217421-01A1.