Brachytherapy - intracavitary, interstitial, metabolic, contact tumor tissue radiosensitivity, Therapeutic window.
Brachytherapy (coming from the greek Brachy = short distance) is, as we’ve said, a form of radiotherapy where a sealed source of radiation is placed inside or next to the area requiring treatment. The radiation only affects a very localized area around the radiation source, limiting the overall side effects.
Intracavitary
- Intracavitary breast brachytherapy is the placement of a single catheter into the cavity left in the breast after the removal of the tumour (this may be during or after the operation)
- The catheter is then connected to an afterloader which delivers the radiation directly into the cavity.
Interstitial
- Another form of breast brachytherapy, involves the temporary placement of several flexible plastic catheters in the breast tissue which are placed around the tumour at specific angles.
- The angles are chosen to minimise radiation of the breast and maximise radiation of the tumour. Often done as a ‘boost’ after EBRT.
Metabolic
- Uncertain about this, seems to be that radioactive metabolites are injected which then damage the tumour, but this would be radionuclide therapy, maybe query?
Contact tumour radiosensitivity
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Therapeutic window
- Radiation can be temporary or permanent
- Permanent involves implantation of seeds that emit radiation for weeks or months before becoming decayed, often used in prostate cancer
- Dose rate (or intensity) is expressed in Grays per hour, we give low dose for cancers such as in the oral cavity, oropharynx, sarcomas and prostate cancer. High doses (exceed 12 Grays per hour) are used in tumours of cervix, esophagus, lungs, breasts and prostate.