Introduction

The use of discrete gamma ray sources to irradiate tissues is usually referred to as brachytherapy and falls into three distinct applications. Interstitial therapy is where the sources are implanted directly into the diseased tissues. Intracavitary therapy is where the sources are arranged in a suitable applicator to irradiate the walls of a body cavity from inside, in effect the sources are placed in the heart of the tumour in both of these cases. The use of surface applicators is where an external surface of the patient is treated by locally applied sources arranged on an appropriately shaped applicator. While the use of gamma-emitting surface applicators has been largely replaced by the use of electron beams and will not be covered in this chapter, limited use is made of beta plaques and these will be briefly described.

Treatment times vary from:

• A short period of time which may be measured in minutes as in the case of temporary implants

• A long period, over the effective life-time of the radionuclide during the decay phase, in the case of permanent implants.

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