Purpose: Agnew and McGarry presented a suite of images to evaluate software for gamma analysis, and verified with it a comprehensive set of commercial programs [Agnew CE, McGarry CK. A tool to include gamma analysis software into a quality assurance program. Radiotherapy and Oncology. 2016 Mar 1;118(3):568-73]. The purpose of our study was to validate the implementation of gamma analysis in Radiochromic.com (Radiochromic SL, Benifaió, Spain) by using these tests. Two different versions of Radiochromic.com were evaluated: currently available version 3.3 and a pre-release version.
Methods: The Agnew and McGarry's (AG) tests consist of four synthetic geometric images and two clinical images (IMRT and VMAT plans). The synthetic images have known gamma results assuming that the evaluated image is not interpolated. However, real dose distributions are continuous, and more accurate gamma values are obtained by interpolating the evaluated images. The results of the clinical AG tests depend on the interpolation used. Both Radiochromic.com versions apply bicubic interpolation, although the resolution of the interpolated images may differ. Also, the pre-release version has the option of not interpolating, employs parallel computation, and can calculate 1D to 3D gammas.
Results: In the clinical tests, Radiochromic.com v3.3 had a mean passing rate and standard deviation of 99.0 ± 1.4%, while in the pre-release version it was 98.9 ± 1.5%. For comparison, from the AG paper, mean passing rates for FilmQAPro, PTW Verisoft v6.1, and Sun Nuclear SNC v6.5 programs were 96.2 ± 6.0%, 98.8 ± 1.9%, and 98.5 ± 2.1%, respectively. In the synthetic tests, the pre-release version obtained exact results and v3.3 had errors of -0.1 ± 0.5% as a consequence of interpolation.
Conclusion: The accuracy of the implementation of the gamma analysis was validated in both versions of Radiochromic.com.
Funding Support, Disclosures, and Conflict of Interest: B Casar acknowledges partial financial support from the Slovenian Research Agency through the research Grant P1-0389. I Mendez and J Rovira Escutia are co-founders of Radiochromic.com.