Application of Unlaminated Gafchromic EBT3 Film for Surface Dose Measurement in Breast Radiotherapy.

Background: Advanced radiotherapy techniques are widely used for the treatment of breast cancer. Breast cancer treatment often involves acute and late radiation effects on the skin. Quantification of surface dose is crucial due to its impact on skin toxicity, cosmetic outcomes, and local tumor control. Aims: In this study, the feasibility of using unlaminated Gafchromic EBT3 film (Ashland Advanced Materials, Bridgewater, NJ, USA) for quantification of surface dose during breast radiotherapy was explored. Materials and Methods: The dosimetric properties of this film, such as dose response, dose rate dependence, orientation dependence, and Ultraviolet-spectrum analysis, were also studied. A CIRS thorax phantom (CIRS Inc. Norfolk, Virginia) with a removable breast attachment was used for surface dose measurement. Tangential beam three-dimensional-conformal radiotherapy (3D-CRT) and 7-field intensity-modulated radiotherapy (IMRT) treatment plans were generated on the computed tomography images of the CIRS thorax phantom. The unlaminated EBT3 films were positioned on the breast attachment, at medial and lateral positions, and the treatment was delivered using 6 megavoltage X-rays generated by a TrueBeam medical electron linear accelerator (Varian Medical Systems, Palo Alto, USA). The exposed films were scanned with an EPSON 10000XL flatbed scanner, and the percentage surface dose was determined by taking the ratio of the measured dose and prescribed dose. Results: The average percentage surface doses for 3D-CRT and IMRT techniques were found to be 43.11% and 34.78%, respectively. Conclusion: This study demonstrated the feasibility of using unlaminated EBT3 Gafchromic film for surface dose evaluation in breast radiotherapy, providing valuable insights to optimize treatment strategies and enhance patient outcomes.