«Internal» radiotherapy
Brachytherapy is a method of irradiation which involves placing radioactive sources in contact with or even within a tumour. This treatment is therefore targeted directly at the area which is affected by the cancer. Brachytherapy is particularly useful in the treatment of gynaecological and ENT cancers and cancer of the prostate.
Depending on the positioning of the radioisotopic material in relation to the tumour, one can distinguish two types of brachytherapy:
- Contact brachytherapy: the source is placed in contact with the tissue to be irradiated using the existence of natural body cavities, which serve as receptacles for the radioactive material and its carrier.
- Interstitial brachytherapy: the sources are inserted within the tumour as, for example, in tumours of the tongue, breast and prostate.
Different treatment types
Different treatment types are defined by the rate of delivery of the dose (ratio of the total dose delivered and the time during which the radioactive sources remain within the tissue):
- High dose-rate brachytherapy (HDR): in this situation, the treatment duration is a few minutes and is repeated between 2 and 10 times.
- Low dose-rate brachytherapy (LDR): the radioactive sources are left in place continuously over several days and this form of treatment does require that the patient remains in hospital for some days.
- Pulsed brachytherapy is a method which employs a small radioactive source, which is moved step by step within the tissue to be irradiated. Each pulse lasts for 5 to 45 minutes and is administered at hourly intervals throughout the 24 hours.
- In the treatment of prostate tumours, seeds of iodine-125 are inserted under anaesthesia and left in place indefinitely.
The choice between the various methods depends on tumour type. When admission is necessary it is to a single room. Because radioactivity is being used, visiting may be restricted.
