Dose Distribution Evaluation and Independent Quality Check of Spherical INTRABEAM™ Applicators via Radiochromic EBT۲ 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 EBT۲ film. Material and Methods: Theindependent quality check of ۱.۵, ۳.۵, and ۵-cm spherical Intrabeam™ applicators was accomplished using particular EBT۲ film cutting pieces with internal rounded edges in a water phantom. Prior to this measure, the film was calibrated at three distances from the ۵-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 <۰.۰۵). 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, ۱۴.۹۷%, ۱۷.۵۹%, and ۳۰.۹۲% of the relative mean doses were measured at ۱ cm depth of ۱.۵-cm, ۳.۵-cm, and ۵-cm applicators, respectively. A ۱۰%/۱mm 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 oftheIntrabeam device.

Keywords:

Analysis of Variance , Calibration , x-rays , water