Dosimetric Pitfall for Relative Dosimetry in Electron Disequilibrium Region

Various types of radiation detectors are used to measure relative dose distributions for therapeutic electron and photon beams. Most detectable signals from a radiation detector are correlated to the energy imparted δε to the detector [1]. This, in turn, is related to the absorbed dose in the detector, Ddet. Table I lists types of radiation detectors, their signals, and their relationship to the dose in the sensitive volume of the detectors. The meaning of the dosimetric quantities can be found in Refs. 2 – 4. In this review we will only consider the first three types of detectors, especially ionization chambers and diodes, since they are the most commonly used in acquiring beam data.