ABSTRACT
In this chapter, the author describes that the various types of commercially available detectors used in radiotherapy are described along with their particular dosimetric characteristics and clinical applications. Radiation detectors that provide point measurements have a long and extensive use in radiotherapy. Although many radiation detectors provide point dose measurements, they can also be utilized to obtain three-dimensional dose distributions, as well as provide dose information at regions of interest at various anatomical sites such as eyes, skin, and scrotum. Active detectors provide an instantaneous reading while passive detectors require some time post-irradiation for a reading. Active detectors such as ionization chambers and diodes provide an immediate "real-time" reading. The accuracy of a detector measurement is the degree of closeness of the measured value to the actual value. Since radiotherapy utilizes polyenergetic radiation, the ideal radiation detector would have a response independent of energy. However, energy-compensated diodes have been developed that decrease their over-response to lower energy photons.
