Biophysical characterization of a relativistic proton beam for image-guided radiosurgery

Abstract

We measured the physical and radiobiological characteristics of 1 GeV protons for possible applications in stereotactic radiosurgery (image-guided plateau-proton radiosurgery). A proton beam was accelerated at 1 GeV at the Brookhaven National Laboratory (Upton, NY) and a target in polymethyl methacrylate (PMMA) was used. Clonogenic survival was measured after exposures to 1–10 Gy in three mammalian cell lines. Measurements and simulations demonstrate that the lateral scattering of the beam is very small. The lateral dose profile was measured with or without the 20-cm plastic target, showing no significant differences up to 2 cm from the axis A large number of secondary swift protons are produced in the target and this leads to an increase of approximately 40% in the measured dose on the beam axis at 20 cm depth. The relative biological effectiveness at 10% survival level ranged between 1.0 and 1.2 on the beam axis, and was slightly higher off-axis. The very low lateral scattering of relativistic protons and the possibility of using online proton radiography during the treatment make them attractive for image-guided plateau (non-Bragg peak) stereotactic radiosurgery.

Radiation Protection of Yeast Cells and DNA by Epigallocatechin Gallate and Epicatechin

“…The α/β values in our results are more than an order of magnitude higher than the previously reported values of gamma and proton irradiation of mammalian cells ability. 16,17) The α/β value is related to the radiation resistance of cells. It is considered that yeast cells are more resistant to ionizing radiation than mammalian cells.…”