Room: Stars at Night Ballroom 1
Purpose: This work evaluates a new 2D reusable radiochromic sheet (Presage), and clinical application as an economic alternative to film and as a novel radiochromic bolus material.
Methods: The 0.5cm sheets were evaluated in representative film and bolus applications. Dose readout in the sheets was achieved with an Epson flat-bed scanner, and was acquired at 10 minutes post-irradiation. Film applications included patient-specific IMRT per-field QA, and a cumulative TG-119 C-Shape test for IMRT commissioning. Sheet doses were compared to equivalent EBT and Eclipse treatment planning system dose distributions. The radiochromic bolus application involved a chest-wall scar 9e electron treatment simulated on an anthropomorphic phantom. The sheet doses were compared with the Eclipse TPS dose distribution, EBT film readout, and OSL dosimeter measurements.
Results: The sheets exhibited a radiation induced optical density change that was linearly proportional to dose, and were reusable at least 10 times (1% consistency of response). The gamma comparison at 3% 3mm of the IMRT field yielded a 97% pass-rate between the Presage sheet dose and EBT. For the TG-119 test, the gamma comparison between the sheets and Eclipse was 93% at 5% 3mm. In the bolus application, a large region of 14% under-dose was identified when comparing the Presage sheet readout with Eclipse expectations. The sheet dose measurements agreed well with EBT and OSL measurements where Presage sheet, EBT, and OSL measurements were within 2% RMS difference, compared with 7% RMS difference when EBT, Presage, and OSL measurements were each compared with Eclipse.
Conclusion: The results indicate that the reusable Presage sheets can function effectively as a radiochromic film alternative and present a significant economic advantage due to their reusability. As a radiochromic bolus they present the opportunity for a novel in-vivo secondary verification of superficial dose.
Funding Support, Disclosures, and Conflict of Interest: Research reported in this publication was supported by National Institutes of Health under award number 1R41CA217421-01A1.