assessment of surface and build-up doses for a 6 mv photon beam using parallel plate chamber, ebt3 gafchromic films, and primo monte carlo simulation code

Background: accurate assessment of surface and build-up doses has a key role in radiotherapy, especially for the superficial lesions with uncertainties involved while performing measurements in the build-up region. objective: this study aimed to assess surface and build-up doses for 6 mv photon beam from linear accelerator using parallel plate ionization chamber, ebt3 gafchromic films, and primo monte carlo (mc) simulation code. material and methods: in this experimental study, parallel plate chamber (ppc05) and ebt3 gafchromic films were used to measure doses in a build-up region for 6 mv beam from the linear accelerator for different field sizes at various depths ranging from 0 to 2 cm from the surface with 100 cm source to surface distance (ssd) in a solid water phantom. measured results were compared with monte carlo simulated results using penelope-based primo simulation code for the same setup conditions. effect of gantry angle incidence and ssd were also analyzed for depth doses at the surface and build-up regions using ppc05 ion chamber and ebt3 gafchromic films. results: doses measured at the surface were 14.78%, 19.87%, 25.83%, and 31.54% for field sizes of 5×5, 10×10, 15×15, and 20×20 cm², respectively for a 6 mv photon beam with a parallel plate chamber and 14.20%, 19.14%, 25.149%, and 30.90%, respectively for ebt3 gafchromic films. both measurement sets were in good agreement with corresponding simulated results from the primo mc simulation code; doses increase with the increase in field sizes. conclusion: good agreement was observed between the measured depth doses using parallel plate ionization chamber, ebt3 gafchromic films, and the simulated depth doses using primo monte carlo simulation code.