External beam radiation treatments are given on a machine called a linear accelerator. This machine uses electricity to create the radiation beams.
For all of the techniques described below, you will need a planning CT scan prior to treatment (See Your Treatment Pathway (please see "Your treatment pathway" on the "Having RT" tab for more information). You may also need other types of scans such as MRI or PET.
Your radiation therapists may also take additional images (e.g. scans and x-rays) to make sure that your position is correct before giving the radiation each day. This is called image-guided radiation therapy, or IGRT, and is often built into most radiation techniques in BC.
Intensity modulated radiation therapy, or IMRT, is radiation therapy where the shape of the radiation field changes as treatment is delivered. The radiation field is shaped so that the tumour, or where the tumour was, can get a high dose, while the normal tissue is avoided.
Volumetric Modulated Arc Therapy, or VMAT, is a form of intensity modulated radiation therapy (IMRT). The big difference with VMAT is the treatment machine moves around you in a circle as the radiation is given. This machine motion allows for further shaping of the field.
3D conformal radiation therapy, or 3DCRT, is radiation therapy given to closely fit the treatment area. First, the radiation oncologist decides what area needs to have treatment. The radiation beams are then shaped to match this area. The beams from the treatment machine are also angled to target the treatment area and avoid healthy tissue.
Stereotactic radiation therapy uses special equipment to position the patient. There are two types of special equipment: masks and body moulds (a hard cushion fitted to your body). This equipment allows us to give radiation in a more precise way. When we use this equipment, we can give higher doses of radiation with each treatment.
Stereotactic Radiation Therapy is not appropriate for all types of cancers or tumour locations.
When stereotactic radiation is delivered to the body (lung, liver, bone, etc.), it is called stereotactic body radiation therapy (SBRT) or stereotactic ablative radiation therapy (SABR). This radiation is delivered in 3 to 8 treatments. The treatments might not be every day, but may be spaced out with a day in between treatments.
If you need a body mould, this will be created during the radiation planning process. You may also need a mask, or shell, around your head and shoulders.
When stereotactic radiation is delivered to the brain, it is either delivered in one of two ways:
- a single treatment called stereotactic radiosurgery (SRS), or
- multiple treatments, called stereotactic treatment (SRT).
For stereotactic treatments to the brain, a specialized mask is created that keeps your head very still. This mask will be tight but shouldn’t be uncomfortable.