Document Type : Original Paper
Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
Medical Physics Research Centere, Faculty of medicine, Mashhad University of Medical Sciences, Mashhad, Iran
Cancer Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
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: Theindependent 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 oftheIntrabeam device.