Radiation Therapy

Radiation Therapy

You have been referred to a radiation oncologist by your primary care doctor or one of your other cancer doctors. Our nurse will help you make an appointment to meet the radiation therapy team.

Before starting radiation therapy, you may need to get X-rays, an MRI or a CT scan (CAT scan). Your doctor will let you know if this is necessary.

Radiation Therapy CT ScanHere at the OHSU Knight Cancer Institute, we use the most advanced technology for treating brain tumors with radiation. This includes the Novalis Tx™ with BrainLAB technology and state-of-the-art Varian linear accelerators.  We've chosen the Novalis Tx system rather than similar technologies like Gamma Knife or CyberKnife.

External Beam Radiation Therapy

External beam radiation therapy is the most common type of radiation for brain cancer. A movable linear accelerator controlled by a computer creates the radiation beam. Instead of delivering many beams at once, the machine moves around the patient, sending radiation to the tumor from different angles.

External beam radiation treatments are usually given Monday through Friday. A certified radiation therapist administers the treatment and monitors the patient’s progress. Most visits take 15 to 45 minutes, although the actual treatment time is only a few minutes.

Stereotactic radiosurgery

Stereotactic radiosurgery is one type of external beam radiation therapy. A small tumor area receives a large dose of radiation in one treatment session. Stereotactic radiosurgery is mostly used for brain tumors and other tumors inside the head. The dose can sometimes be repeated if needed.

Your doctor might also decide to give the same dose or a slightly higher dose in several treatments. This is called fractionated stereotactic radiosurgery. It can also be called stereotactic radiotherapy.

For some stereotactic radiosurgery treatments, the patient wears a head frame attached to the skull. This lets your radiation therapy team aim the radiation beams precisely and avoid healthy tissue. Imaging scans, such as CT (CAT) scans and MRI scans, help pinpoint the tumor’s exact location. Radiation is sent to the tumor from a machine. The radiation is very precise, and nearby tissues are protected as much as possible.

Novalis Tx stereotactic radiosurgery for brain cancer 

At the OHSU Knight Cancer Institute, we use the Novalis Tx radiosurgery system to treat brain tumors. Novalis Tx stereotactic radiosurgery is one of the most advanced cancer treatment options available.

Three-dimensional conformal radiation therapy (3D-CRT)

This type of external beam radiation is also called conformal external beam radiation therapy. During treatment, the machine delivers radiation that is shaped to match the brain tumor. Radiation is sent to the tumor from different directions, reaching more tumor cells.  

If you have 3D-CRT radiation for brain cancer, you might wear a mask to help keep your head in position. This allows your treatment team to aim the radiation beams more accurately. Using a very precise beam allows your doctor to increase the radiation dose to destroy more brain tumor cells. It also helps protect healthy tissue.  

Intensity modulated radiation therapy (IMRT)

Intensity modulated radiation therapy (IMRT) conforms to shape of the brain tumor like 3D-CRT. The strength of the radiation beam can be lowered in areas that need less treatment, and increased where there are more tumor cells. This helps kill more cancer while protecting healthy tissue. It can also decrease side effects.

Whole brain radiation therapy

The whole brain is sometimes treated with radiation therapy. If you have metastatic brain cancer, you might have this type of treatment. Whole brain radiation therapy can treat metastatic brain tumors throughout the brain, including brain tumors that are too small to see on a CT or MRI scan.