Brachytherapy is a form of localized radiation therapy that is used to kill cancer cells and shrink tumors.
The treatment is usually overseen by a radiation oncologist who evaluates the patient and plans the appropriate therapy, including the area of the body that needs to be targeted and the amount of radiation that is needed.
A range of specialists are involved in the different aspects of brachytherapy and examples of the professionals found in a treatment team include an oncologist, dosimetrist, radiation therapist, nurse and a surgeon.
Brachytherapy may be given on a permanent or temporary basis. In permanent brachytherapy, seeds containing the radioactive material are implanted either inside or nearby the tumor. Low dose radiation is gradually absorbed over time and eventually fades after six months.
For temporary brachytherapy, a catheter or applicator is a used to deliver the radioactive material to a target site. In cases of low dose radiotherapy, this material is usually placed in the delivery device for 12 to 24 hours before being removed, while high dose radiation may only be administered for a few minutes. Various different radioactive sources are used in brachytherapy. Some examples include:
- Radioactive iodine
- Radioactive palladium
- Radioactive cesium
- Radioactive iridium
Once the material is selected, it is delivered to the target site using one of two methods:
- Hot loading – The radioactive material is placed manually and directly into the target tissue.
- Afterloading – A delivery device is placed into position using imaging studies and then loaded with the radioactive material by hand (manual afterloading) or by an automated machine (automatic remote afterloading).
Brachytherapy radiation doses
Treatments may be delivered at a high dose-rate (HDR) over 10 to 20 minutes per session in bursts or at a low dose-rate (LDR) over 20 to 50 hours. Treatment can also be delivered in periodic pulses, referred to as pulsed dose-rate or PDR.
Preparation for brachytherapy
Before brachytherapy, a patient undergoes tests to check their general health. Examples of these tests include ECG, routine blood tests, pre-treatment ultrasound, MRI scan, CT scan and chest X-ray. The bowel is cleared before the procedure, especially if it involves the pelvic organs.
Before brachytherapy begins, an intravenous drip is used to administer an anesthetic to the patient. Depending on the extent of the operation, general or local anesthesia or a sedative may be delivered.