Radiotherapy Proton Interactions in Matter

Abstract

A survey of physics useful to proton radiotherapy, centered on stopping, scattering and hard scatters: 1. Introduction 2. The fundamental formula dose = fluence x mass stopping power. Practical units, comments on effective stopping power. 3. Range: experimental definition, Beth-Bloch CSDA theory, range-energy tables and approximations, range straggling. 4. Multiple Coulomb Scattering: suggested reading, elements of Moliere theory, the Gaussian approximation, scattering power. 5. Hard scatters (nuclear interactions): contributing reactions, shape and size of the halo, experiment, halo as a Monte Carlo test. 6. Bragg curve (effective stopping power): limiting cases S_em and S_mixed, transverse equilibrium, computing S_em, measuring S_mixed, parameterizing the nuclear halo. 7. Looking ahead: Fermi-Eyges theory, the Preston and Koehler rules, a proton dose algorithm from first principles. Appendices: A. Acronyms B. Symbols C. Gaussians D. Relativistic kinematics E. Simple design problems.

52 pages, 27 figures. Version, with all appendices and figures, of Ch.2, "Proton Therapy Physics," 2nd edition, H. Paganetti ed., Taylor & Francis (2018) (to be published)