What is brachytherapy?
Brachytherapy involves radiation delivered from a tiny source implanted directly into or next to the tumour.
These sources produce gamma-rays, which have the same effect on cancer cells as X-rays.
This treatment reduces damage to surrounding healthy tissue, limiting side effects.
Several brachytherapy techniques are used in cancer treatment.
- Interstitial brachytherapy - uses a radiation source placed within tumour tissue, such as within a prostate tumour
- Intracavitary brachytherapy - uses a source placed within a surgical cavity or a body cavity, such as the chest cavity, near a tumour
- Episcleral brachytherapy - used to treat melanoma inside the eye, using a source that is attached to the eye
In brachytherapy, radioactive isotopes are sealed in tiny pellets or “seeds.”
These seeds are placed using delivery devices, such as needles, catheters, or some other type of carrier.
The isotopes then decay naturally, giving off radiation that damages nearby cancer cells.
After a few weeks or months, the isotopes decay completely and no longer give off radiation.
The seeds won’t cause harm if they are left in the body.
Brachytherapy may be able to deliver higher doses of radiation to some cancers than external beam radiation therapy – while causing less damage to normal tissue.
There are two main types of brachytherapy: low dose rate (LDR) and high dose rate (HDR).
Low dose rate brachytherapy
Low dose rate (LDR) brachytherapy can be thought of as ‘take-away’ radiation.
In this therapy, small radioactive ‘seeds’ are implanted near or in the tumour.
These stay permanently in place, releasing small amounts of radiation over several weeks or months.
Most commonly in Australia and New Zealand, this technique is used for treating primary prostate cancers.
Men can get back to their usual activities within a day or two of having the ‘seeds’ inserted.
In low-dose-rate treatment, cancer cells receive continuous low-dose radiation from the source over a period of several days.
High dose rate brachytherapy
High dose rate (HDR) brachytherapy is similar to LDR brachytherapy, but the delivery is a bit different.
Instead of staying in the body permanently, the radioactive sources are removed at the end of each treatment session.
Also, the radiation sources deliver a more intense dose of radiation during each session (usually 1-3 sessions).
It is often given with external beam radiation therapy to provide a “boost” of radiation to a tumour while sparing surrounding normal tissue.
During treatment, a robotic machine attached to delivery tubes placed inside the body guides one or more radioactive sources into or near a tumour. It then removes the sources at the end of each treatment session.
High-dose-rate treatment can be given in one or more treatment sessions.