External beam radiation therapy (EBRT) can be given using different techniques and different types of radiation. Your treatment centre may not offer all methods, but your radiation oncologist will recommend the most appropriate combination for you.
Learn more about these types of EBRT:
- Three-dimensional conformal radiation therapy (3DCRT)
- Intensity-modulated radiation therapy (IMRT)
- Image-guided radiation therapy (IGRT)
- Stereotactic radiosurgery (SRS)
- Stereotactic body radiation therapy (SBRT)
- Proton therapy
Three-dimensional conformal radiation therapy (3DCRT)
- Common type of EBRT.
- Uses imaging scans (see previous page) to help plan the treatment.
- A computer uses the scans to precisely map the location of the cancer within the body.
- The radiation is then shaped (conformed) so that the cancer receives most of the radiation, and surrounding tissues receive much less.
Intensity-modulated radiation therapy (IMRT)
- Highly accurate type of conformal radiation therapy.
- Shapes and divides multiple radiation beams into tiny beams (beamlets) that vary in strength.
- Widely used for most cancer types, especially for curative treatment.
- Volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT) are specialised forms of IMRT that use a treatment machine that rotates around the body.
Image-guided radiation therapy (IGRT)
- Uses a treatment machine that takes x-rays or scans at the start of each session.
- Markers (usually grains of gold) may be inserted into the cancer so they can be seen in the x-rays or scans.
- Positioning can be very finely adjusted, often to millimetre accuracy.
- Radiation oncologists may recommend IGRT for areas likely to be affected by movement, such as the lungs and liver when you breathe, or the prostate when the fullness of your bladder or bowel varies.
Stereotactic radiosurgery (SRS)
- Specialised type of radiation therapy.
- Combines many small radiation fields to give precisely targeted radiation in one single high dose.
- Used to treat small cancers in the brain while minimising the radiation reaching healthy brain tissue.
- A custom-made mask keeps the head still during SRS.
- Despite the name, this is not surgery and does not involve any surgical cuts.
Stereotactic body radiation therapy (SBRT)
- Similar to SRS, this method allows a few high doses of radiation to be delivered very precisely.
- May be used to treat small cancers in the body, including small lung or liver cancers or small metastases (cancer that has spread away from the primary cancer).
- Sometimes called stereotactic ablative body radiation therapy (SABR).
- Uses radiation from protons rather than x-rays.
- Protons are tiny parts of atoms with a positive charge that release most of their radiation within the cancer – useful when the cancer is near sensitive areas, such as the brainstem or spinal cord, especially in children.
- Special machines, known as cyclotrons and synchrotrons, are used to generate and deliver the protons.
- Proton therapy is not yet available in Australia (as at December 2017), but there is funding in special cases to allow Australians to travel overseas for treatment.