Investigating the Dosimetric Characteristics of Microbeam Radiation Treatment

Background: High‑radiation therapeutic gain could be achieved by the modern technique of microbeam radiation treatment (MRT). The aim of this study was to investigate the dosimetric properties of MRT. Methods: The EGSnrc Monte Carlo (MC) code system was used to transport photons and electrons in MRT. The mono‑energetic beams (۱ cm × ۱ cm array) of ۵۰, ۱۰۰, and ۱۵۰ keV and the spectrum photon beam (European Synchrotron Radiation Facility [ESRF]) were modeled to transport through multislit collimators with the aperture’s widths of ۲۵ and ۵۰ μm and the center‑to‑center (c‑t‑c) distance between two adjacent microbeams (MBs) of ۲۰۰ μm. The calculated phase spaces at the upper surface of water phantom (۱ cm × ۱ cm) were implemented in DOSXYZnrc code to calculate the percentage depth dose (PDD), the dose profile curves (in depths of ۰–۱, ۱–۲, and ۳–۴ cm), and the peak‑to‑valley dose ratios (PVDRs). Results: The PDD, dose profile curves, and PVDRs were calculated for different effective parameters. The more flatness of lateral dose profile was obtained for the ESRF spectrum MB. With constant c‑t‑c distance, an increase in the MB size increased the peak and valley dose; simultaneously, the PVDR was larger for the ۲۵ μm MB (۳۳.۵) compared to ۵۰ μm MB (۲۱.۹) beam, due to the decreased scattering photons followed to the lower overlapping of the adjacent MBs. An increase in the depth decreased the PVDRs (i.e., ۵۴.۹ in depth of ۰–۱ cm). Conclusion: Our MC model of MRT successfully calculated the effect of dosimetric parameters including photon’s energy, beam width, and depth to estimate the dose distribution.

کلیدواژه ها:

Dosimetry ، microbeam radiation treatment ، Monte Carlo simulation