Image-guided brachytherapy

Abstract

Brachytherapy consists in the administration of radiation in intimate contact with the tumour, with a low exposure of neighbouring healthy tissues. Its use began in the early XX century and it has developed since then: different radioisotopes, systems of remote treatment, computer programs making individual dose calculation possible. In recent years there have been changes affecting two aspects of brachytherapy. In the first place, the incorporation of imaging techniques such as echography, computerised tomography (CT) and magnetic resonance (MR), indispensable for diagnosis and tumoural staging. Their use when the implant is being done helps in guiding and carrying out the operation with greater precision. In the second place, the use of CT, MR and echography makes better coverage of the tumour possible, or reduces the dose to healthy organs. They are used in inverse planning systems, which carry out dose calculation on the basis of the doses to be administered to the tumour and healthy organs. In these planning programs it is possible to make calculations more rapidly, taking account of the placement of the source at each moment in time. This technique, called real-time planning, is starting to show advantages in the treatment of prostate cancer. Incorporation of imaging techniques and mprovements in calculation systems mean that brachytherapy is currently playing an important role in treating cancer of the prostate, cervix, breast, head and neck tumours, bronchial tubes or oesophagus.