In-vivo dosimetry in total body irradiation using GafchromicTM EBT-3 film: A retrospective analysis for quality assurance

Background: total body irradiation (tbi) is a specialized radiotherapy technique and it varies from routine radiotherapy techniques that involve a complex treatment procedure. it is therefore mandatory to perform an in-vivo dosimetry check to ensure dose accuracy and homogeneity during treatment. there is also a clear demand for invivo dose validation which must be reliable. the primary objective of this work is to review in-vivo dosimetry measured for our tbi patients using film. materials and methods: in this study, in-vivo dosimetric data of 185 patients who received tbi during 2015 to 2021 were evaluated. the measurements were performed at 14 anatomical sites using gafchromictm ebt-3 film (the ashland inc., bridgewater, usa). for midplane dosimetry, a special tbi phantom was designed and used for measurements. result: for most of the patients, the in-vivo dosimetry result and the mean dose to the whole body were within ±10% (90.1% - 110%) of the prescription dose. the standard deviation was calculated for all the patients and the values were observed between 2.4cgy to 24cgy. also, the analysis shows that both surface and mid-plane dosimetry were within the acceptable limits of ±10% of prescription dose. the mean mid-plane dose with film and ionization chamber shows 1.5% variation at the umbilicus. conclusion: this extensive patient data analysis, as well as the reproducibility of patient dosimetry values and dose homogeneity of ±10% from the prescription dose, proves that the tbi treatments at our center meet the acceptable limits and ebt3 films are reliable in tbi in-vivo dosimetry.