dose distribution evaluation and independent quality check of spherical intrabeam™ applicators via radiochromic ebt2 film measurement

Introduction: the present study was conducted to implement a simple practical independent quality check of depth dose and isotropy of the intrabeam™ therapeutic x-ray machine using radiochromic ebt2 film. material and methods: the independent quality check of 1.5, 3.5, and 5-cm spherical intrabeam™ applicators was accomplished using particular ebt2 film cutting pieces with internal rounded edges in a water phantom. prior to this measure, the film was calibrated at three distances from the 5-cm applicator in water to clarify the effects of beam spectrum and dose rate alteration on film response. to this end, three calibration curves were plotted. results: the results of the one-way analysis of variance showed a critical difference between film pieces receiving equal doses at various distances (p<0.05). therefore, depth dose curves were designed using all three calibration curves. smaller applicators represented steeper dose fall-off, compared to the larger sizes. in this regard, 14.97%, 17.59%, and 30.92% of the relative mean doses were measured at 1 cm depth of 1.5-cm, 3.5-cm, and 5-cm applicators, respectively. a 10%/1mm gamma index was satisfied for the lateral dose evaluation of corresponding depth relative to z-direction. conclusion: the approach implemented in this study could be carried out as a rapid monthly quality check method for the dose distribution evaluation of the intrabeam device.