SU‐GG‐J‐36: Application of Gafchromic XR‐RV2 Film for Small Animal Irradiation Dosimetry

Purpose: To assess the accuracy of self‐developing Gafchromic XR‐RV2 film for the dosimetry of small animal kilovoltage x‐ray irradiation. Method and Materials: Two kilovoltage x‐ray beams (100kVp and 150kVp) for small animal irradiation from a Faxitron machine were employed in this study. The doses of a point at the center of a round field with diameter of 20cm in a 30×30×10 cm³ solid water phantom at a depth of 1cm were measured via Gafchromic XR‐RV2 films and a Farmer ion chamber. The films, cut into small samples (3.5×1.5cm² in size), were from the same batch to remove the variability between batches. Two film calibration curves were established for the two beams. The films were scanned with an Epson V700 flat‐bed scanner 24 hours after exposure and analyzed with FilmQA software. The doses of the same point for a round field with diameter of 1cm were also measured. Results: The Gafchromic XR‐RV2 film calibration curves were found to be weak dependent of beam energy (<8% difference of the pixel values between 100kVp and 150kVp). The agreement of measured doses for big field between Gafchromic XR‐RV2 films and Framer chamber were within 5% (−4.0% to 5.0%). While for small field irradiation, large difference (up to 75%) of measured doses was observed, which indicates that Farmer chamber underestimated the point dose due to field size is not big enough to cover chamber body. Conclusion: The Gafchromic XR‐RV2 film can provide acceptable accuracy of dose measurements for kilovoltage x‐ray irradiation and it is more accurate than Farmer ion chamber for small field irradiation that are often used in small animal treatments. The combination of Gafchromic XR‐RV2 film with flat‐bed scanner represents a low‐cost and viable dosimetry tool for small animal irradiation.