dosimetry

lithium fluoride

ionization chambers

polymer gel

x-ray tube

using monte

dose response

dose distribution

radiation exposure

dose rate

Medical Physics

Purpose: In this study, newly formulated XR‐RV3 GafChromic ® film was calibrated with National Institute of Standards and Technology (NIST) traceability for measurement of patient skin dose during fluoroscopically guided interventional procedures. Methods: The film was calibrated free‐in‐air to air kerma levels between 15 and 1100 cGy using four moderately filtered x‐ray beam qualities (60, 80, 100, and 120 kVp). The calibration films were scanned with a commercial flatbed document scanner. Film reflective density‐to‐air kerma calibration curves were constructed for each beam quality, with both the orange and white sides facing the x‐ray source. A method to correct for nonuniformity in scanner response (up to 25% depending on position) was developed to enable dose measurement with large films. The response of XR‐RV3 film under patient backscattering conditions was examined using on‐phantom film exposures and Monte Carlo simulations. Results: The response of XR‐RV3 film to a given air kerma depended on kVp and film orientation. For a 200 cGy air kerma exposure with the orange side of the film facing the source, the film response increased by 20% from 60 to 120 kVp. At 500 cGy, the increase was 12%. When 500 cGy exposures were performed with the white side facing the x‐ray source, the film response increased by 4.0% (60 kVp) to 9.9% (120 kVp) compared to the orange‐facing orientation. On‐phantom film measurements and Monte Carlo simulations show that using a NIST‐traceable free‐in‐air calibration curve to determine air kerma in the presence of backscatter results in an error from 2% up to 8% depending on beam quality. The combined uncertainty in the air kerma measurement from the calibration curves and scanner nonuniformity correction was ±7.1% (95% C.I.). The film showed notable stability. Calibrations of film and scanner separated by 1 yr differed by 1.0%. Conclusions: XR‐RV3 radiochromic film response to a given air kerma shows dependence on beam quality and film orientation. The presence of backscatter slightly...

Calibration of GafChromic XR‐RV3 radiochromic film for skin dose measurement using standardized x‐ray spectra and a commercial flatbed scanner