Monte Carlo Simulation of Limitations of Bremsstrahlung Radiation for Microbeam Radiation Therapy

Neba Robinson Neba 
with D. Wells, V. Dimitrov, A. Hunt, F. Harmon, W. Beezhold
Idaho Accelerator Center, Department of Physics
Idaho State University

Microbeam Radiation Therapy (MRT) is an innovative preclinical radiation therapy technique where tissue is irradiated by passing a beam of radiation through microscopically thin slices of parallel microplanar multi-slit collimator. This method has drawn wide attention from its two fold advantage of its ability to damage tumor cells while preferentially sparing healthy surrounding tissue. Previous studies on MRT use x-rays from synchrotron radiation sources where radiation is passed through a multi-slit collimator with microscopically thin slit widths and center-to-center (c-t-c) distances. Directly irradiated micro-slices of tissue are referred to as “peak” dose regions separated by “valley” dose regions. The motivation for this work lies in the fact that the cost of building, running and maintaining a synchrotron facility presents a great limitation to the potential implementation of microbeam radiation therapy around the world (if it becomes clinically available). It will be much more cost effective if this potential treatment technique works with conventional radiotherapy electron linear accelerators or pulsed-power electron accelerators which are less expensive to buy, to run and maintain, and can fit into conventional radiotherapy rooms. In this work we investigated the limits to peak-to-valley dose ratios with electron linear accelerators or pulsed-power electron accelerators, and compared these results with those obtained using synchrotron radiation sources. We simulated the PVDR (peak-to-valley dose ratio) as a function of electron beam energy, beam hardening and the peak and valley collimation widths and spacing on multi-slit collimator.


* Department of Defense (DOD), award no: FA8650-04-2-6541