Monte Carlo optimization of a microbeam collimator design for use on the small animal radiation research platform (SARRP).

Monte Carlo optimization of a microbeam collimator design for use on the small animal radiation research platform (SARRP). Phys Med Biol. 2018 Aug 03;: Authors: Esplen NM, Chergui L, Johnstone CD, Bazalova-Carter M Abstract Microbeam radiation therapy (MRT) is a pre-clinical, spatially-fractionated treatment modality noted for its ability to achieve a large differential response between normal and tumoral tissues. In the present study, TOPAS Monte Carlo (MC) simulations were used to optimize the design of a compact, affordable multi-slit collimator (MSC) suitable for use with the small animal radiation research platform (SARRP). MRT dose distributions in a (1×1×3)cm<sup>3</sup> water phantom were simulated for a tungsten MSC using different focal spot sizes (0.4,3mm), beam energies (40,80,220kVp), slit widths (100,125,150,175,200µm), collimator thicknesses (1.5,2.5,3cm) and collimator-to-surface distances (CSD of 1 and 3cm). Key MRT figures of merit, namely the peak-to-valley dose ratio (PVDR), full-width at half-maximum (FWHM) and peak dose rate were determined. Use of the small focal spot maximized the PVDR (40 at surface) and reduced the system's sensitivity to changes in CSD, but decreased the collimated beam output to 55.2cGy/min. The large focal spot was ill-suited for large CSD irradiations, but increased the beam output by a factor of 2.8, to 153.0cGy/min, and decreased the sensitivity to change...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research