Every day applications of radiation medicine help millions of patients worldwide. Some techniques enable physicians to see inside the human body creating digital images using short-lived radioisotopes. These are called diagnostic techniques.  Others which enable targeted and precise radiation treatment of cancer are therapeutic techniques. In general, radiation and radioisotopes find applications in the following categories of health care:
1) External beam therapy
2) Brachytherapy
3) Nuclear medicine and
4) Radiation Sterilisation of health care products

It is used for controlling or eliminating cancerous growths formed by rapidly dividing cells. For radiotherapy to effect a cure, it is essential that the correct amount of radiation (absorbed dose) be delivered to the patient. Too small a dose, and one or more cancerous cells may survive, leading to recurrence of the disease. Too large a dose, and the healthy tissue surrounding the tumour may be destroyed.  The radiation source is placed in a shielded housing and a well-defined beam of radiation emanating from the source is directed towards the tumour for treatment. Intense Cobalt-60 sources ranging from 9000 to 12000 curies encapsulated and supplied by Board of Radiation and Isotope Technology (BRIT) are being used in most of the 225 teletherapy units set up in 62 cities in India for cancer treatment. Now-a-days, electron accelerators are being widely used for radiotherapy. The advantage of electron beam therapy lies in the precision with which it can irradiate and destroy tumours. Centre for Advanced Technology (CAT), Indore, has developed electron accelerator based teletherapy machine.  In this machine, a microtron (a type of electron accelerator) accelerates electrons to an energy, which depending on the depth of the tumour varies from 6MeV to 12 MeV. For very deep tumours, the electron beam can be converted to X-rays, which then are equivalent to gamma rays from Cobalt-60 source.