ABSTRACT
This chapter explores the different detector technologies to determine the quantity of interest, absorbed dose to water, in proton and carbon ion beams and discusses their application to three-dimensional dosimetry. It explains the energy dependence of the detector response and its effect on the measurement of depth-dose distributions. Light-ions interact with matter by two interaction mechanisms: electromagnetically with atomic electrons and target nuclei and by nuclear interactions with target nuclei which can result in target fragmentation and, in the case of ions heavier than protons, in projectile fragmentation. The chapter discusses the need for relative dosimetry, range measurement, and the accurate determination of spot positions. Nuclear interactions resulting from the strong nuclear force can be categorized as inelastic or nonelastic. The more common instrument to perform reference dosimetry in a particle therapy is the air-filled ionization chamber. The chapter describes the issues of spatial resolution, water equivalence, and energy dependence of detectors, including those used in multidimensional detector systems.
