Electromagnetic radiations in diagnosis and therapy: the case of gamma camera and gamma knife

The gamma camera is a system composed mainly of a scintillation crystal and its associated electronics. It is intended to compose an image, from gamma rays emitted from an organ inside the body that had accumulated a specific compound labeled, for instance with 99mTc. The image formed gives very useful diagnostic information about the organ being investigated. The gamma knife on the other hand is a system intended for radiation therapy of tumors. Its specific advantage is that it delivers a very high radiation dose coming from about 200 thin gamma beams focusing on the tumor while protecting the intervening tissues against receiving any significant radiation dose. Protection of normal tissues in the vicinity of a tumor has been always of central importance in radiation therapy.