Study on beam quality of heavy ion therapeutic beams

Production of fragment particles in a patient's body is one of the important problems on heavy ion therapy. It is required to know the fluence and the energy distribution of each fragment nuclide, so called radiation quality, to understand the biological effect of the incident beam precisely. In this study, angular distributions of the fragment nuclei produced by various beam nuclides, such as B, O, and Ne, in thick water targets were measured with ΔE-E method. As a result, angular distributions under each condition were obtained. Each angular distribution was approximately represented by a Gaussian distribution near the beam axis and an exponential function at angles greater than a few degrees. The width of the Gaussian distribution increases with the target thickness, and the contribution of the nuclear reaction and the multiple-scattering to the width was approximately 2 degrees. (author)