ABSTRACT
The purpose of this chapter is to outline the basics of how inorganic crystals can be used for fiber-coupled luminescence dosimetry, for example, during brachytherapy or external beam radiotherapy with megavoltage (MV) photons. Inorganic crystals generally offer two luminescence signals that can be used for dosimetry: prompt radioluminescence (RL) and optically stimulated luminescence (OSL). The RL signal is present only during the irradiation, whereas the OSL signal can be generated any time after the irradiation by stimulation with an external light source. Under ideal conditions, the RL signal provides an online signal that is proportional to the absorbed dose rate at the position of the crystal, whereas the OSL signal is proportional to the passively integrated absorbed dose. Fiber-coupled luminescence dosimetry with inorganic crystals is similar to the techniques based on organic plastic scintillators described elsewhere in this book. In both cases, the instrumentation can be placed several meters away from the radiation sensing element, and this element can be made relatively small (submillimeter size). Inorganic crystals such as carbon-doped aluminum oxide or copper-doped quartz are less water equivalent than organic plastic scintillators (in terms of both effective atomic number and mass density), but the inorganic crystals offer improved methods for stem signal suppression, and they also seem to provide a higher sensitivity. This chapter first discusses the basics of luminescence physics using carbon-doped aluminum oxide as the key example. Other materials and their applications in medical dosimetry are briefly discussed in Section 17.4.
