◾ Small Field of View Gamma Cameras and Intraoperative Applications
Although early gamma scanners were around in the middle part of the last century, the concept of the gamma camera was invented by Hal Anger in 1952 whilst working at the Donner Laboratory in the University of California in Berkeley, USA. e early prototype consisted of a pinhole collimator and a sodium iodide at intensifying screen placed in front of a photographic plate. e device demonstrated the ability to produce a clinically relevant image, by showing the gamma ray distribution emitted from the patient on the at crystal. e sensitivity of the camera was low and a long exposure time and relatively high amounts of radioactivity were required to produce images. A few years later, Anger improved the prototype design by replacing the gamma ray detector with 4 in. diameter scintillator coupled to an array of seven photomultiplier tubes (PMTs). He also developed ‘Anger arithmetic’ to determine the position of the scintillation event that occurred in the crystal by comparing the photons collected in individual PMTs.