RADIATION-THERAPY POTENTIAL OF INTENSE BACKSCATTERED COMPTON PHOTON BEAMS

For close to 100 years radiation treatments of cancer have used photon radiation produced by the bremsstrahlung process. Free-electron-laser (FEL) technology can produce backscattered Compton photons and this p rovides an opportunity to investigate a new spectrum of photons. In co ntrast to bremsstrahlung, the energy spectrum of the backscattered Com pton photons is peaked at the high energy. The beams also have small d ivergence and hence are highly focused. Dose is calculated using Monte Carlo modeling and the results show that the energy distribution can improve the relative tumor to normal tissue dose distribution especial ly for deep tumors. It is found that fluxes on the order of 10(11) pho tons/s are required. The small divergence means that precision small f ield treatments can be done without collimation and also opens up the possibility of activation applications. These properties may be exploi ted to advantage in the future. This paper reviews the medical therapy potential and discusses benchmarks for FEL performance which are impo rtant to future backscattered Compton therapy applications.