TABLE OF CONTENTS Modern radiotherapy is a highly complex and technically demanding field. The safe, accurate and reproducible delivery of complex three-dimensional radiation distributions must be accomplished in an efficient way. National and international requirements for medical and radiation safety and traceable quality standards must also be fulfilled. Radiation detectors therefore play a crucial supporting role in all aspects of radiotherapy.
A range of different detector systems are used for a variety of different types of measurement. The two main types of measurement are: (i) quality assurance of equipment, and (ii) verification of treatment delivery. The main types of detector fall again into two groups: point detectors, including ionization chambers, semiconductor detectors and thermoluminescent detectors (TLDs), and area detectors, including radiographic film and electronic portal imagers.
In this chapter, the major types of detector system used in radiotherapy will be discussed. The physical principles of operation and typical uses will be presented briefly for each detector. A short introduction to the physics of radiotherapy and an overview of the detection of photons and electrons at the energies commonly used in radiotherapy is also given by way of an introduction. References to more detailed treatments of each topic are included throughout, including reference to some published guidelines and protocols for dosimetric measurements. Radiotherapy dosimetry is a very specialised but well documented and regulated field. Readers wishing to carry out accurate dosimetric measurements are...
