Disadvantages

♦ Many sources emit gamma rays and nursing and medical staff may be exposed to low but significant doses of radiation from the patient. Staff exposure can be minimized by after-loading techniques or the use of low-energy radionuclides.

♦ Large tumours are usually unsuitable, although brachytherapy may be employed as a boost treatment following reduction in size by external beam radiotherapy and/or chemotherapy.

♦ Radiation dose falls off rapidly from the sources according to the inverse square law. In order to treat the required tissue volume adequately, accurate geometric positioning is critical. The spatial arrangement of sources used varies, depending on the type of source applicator, the anatomical position of the tumour, and the surrounding dose-limiting normal tissue. Accurate positioning of sources or applicators requires special skill and training and this is not universally available.

♦ Surrounding structures such as lymph nodes that may contain overt or microscopic cancer will not be irradiated by the implant or intracavity treatment.

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