Radiation Therapy for Brain Tumors

Many patients with brain tumors will undergo radiation therapy over their course of treatment. During radiation therapy, beams of radiation are used to kill tumor cells, causing tumors to shrink.

Radiation therapy can help brain tumor patients in a number of ways. Some patients with smaller, benign tumors may find that radiation therapy is the only treatment they need. For patients with large or malignant tumors, radiation therapy may be used in conjunction with surgery to relieve symptoms and slow tumor growth.

Radiation therapy is complex, especially for patients with brain tumors. It’s important to go to expert providers to get the best possible results.

At Siteman Cancer Center, we have the tools and the team to bring you outstanding care. Our Washington University radiation oncologists are internationally renowned. Their discoveries and innovations, including MRI-guided radiation therapy, Gamma Knife, and Proton Beam, have made treatment safer and more effective for brain tumor patients around the world.

What types of radiation therapy are used to treat brain and spine tumors?

Patients with brain or spine tumors will likely be treated with one of the following methods. All of them provide targeted therapy to tumors.

Some methods are referred to as “radiosurgery” because they can replace an open surgical procedure. These are:

Other methods are referred to as “fractionated radiation therapy” because patients receive treatment incrementally, over a period of time. These include:

In certain cases, a radiation source can be placed inside the patient’s body. This procedure is called brachytherapy.

Gamma Knife radiosurgery

Patients with smaller brain tumors may be good candidates for Gamma Knife radiosurgery. Gamma Knife isn’t actually a knife, but it can achieve the same results as surgery in certain patients. The treatment can often be completed in a single, multi-hour, outpatient session.

One of the chief advantages of Gamma Knife is the way it transmits high-dose radiation directly to the tumor without harming surrounding tissues. This is possible because of its unique delivery mechanism: instead of shooting a single, powerful beam at the tumor, the machine divides the dose into up to 192 weaker beams that converge only at the tumor site.

The radiation oncologists and specialist nurses who staff Siteman’s Gamma Knife Center create a 3D treatment plan for each patient. The radiation will be tailored to the exact shape of your tumor.

Gamma Knife doesn’t burn the tumor away immediately. Instead, it induces cell death over time in the tumor, causing it to shrink gradually over a period of months.

Read more about Gamma Knife radiosurgery at Siteman.

Edge radiosurgery

Edge radiosurgery is a newer form of radiation delivery. It’s performed on a linear accelerator, like fractionated radiation therapies.

However, Edge is different in that it adjusts radiation delivery to subtle movements in the patient’s body and transmits a more powerful dose. Like Gamma Knife, Edge radiosurgery is completed much more quickly than fractionated radiation therapy. The entire course of treatment lasts only one to 5 days. Each session of treatment is fairly short.

Proton beam therapy

Most radiation therapy is delivered in a beam (or beams) of particles called photons. As its name suggests, proton beam therapy instead uses a single, thin stream of proton particles to attack tumor cells.

Proton beam therapy can be an excellent choice for brain and spine tumor patients because of its high precision. The beam is adjusted to stop directly within the tumor, which means that it doesn’t pass through the body the way other radiation beams do. This drastically limits contact between radiation and healthy brain tissue.

Patients receive proton beam therapy five days a week for a period of 5 to 6 weeks.

Siteman was the first facility in the region to offer proton beam therapy, and our radiation oncologists are highly experienced at this form of treatment. Learn more about treatment at Siteman’s S. Lee Kling Proton Beam Center.

Intensity-modulated radiation therapy

Intensity-modulated radiation therapy, or IMRT, is an advanced form of external beam radiation therapy. As its name suggests, the radiation is delivered in beams of varying intensity, which allow the radiation oncologist to mold the radiation to the exact shape of the tumor. This helps protect the healthy tissues surrounding the tumor from harm.

Courses of IMRT last for 3 to 6 weeks. Patients come in for treatment 5 days a week, Monday-Friday.

MRI-guided radiation therapy

This novel approach to radiation therapy was pioneered right here at Siteman. It unites magnetic- resonance imaging to the delivery of radiation, allowing them to see exactly how the radiation is impacting the tumor.

MRI-guided radiation therapy is less commonly used to treat brain tumors. It’s best for tumors surrounded by other organs that inevitably move during treatment. Consequently, patients with spinal tumors are more likely to receive it.


Brachytherapy is a procedure in which tiny pellets of radiation are placed directly into a tumor. In some cases, they can be used to treat patients with glioblastomas.

Does radiation therapy hurt?

Radiation therapy itself is painless. You can’t feel the radiation beams entering your body.

As patients progress through weeks of radiation therapy, however, they may begin to notice discomfort and skin redness at the delivery site. Be sure to speak to your care team about any side effects you may be experiencing, and they will help you with your symptoms.

Preserving cognition in radiation therapy patients

The Washington University radiation oncologists are Siteman Cancer Center want to make radiation therapy better for patients. They recognize that radiation therapy, while helpful for treating tumors, can have unintended consequences, including a weakening of cognitive abilities.

Preserving neuro-cognition following radiation therapy is a major area of concern and research for the radiation oncologists at Siteman. In clinical trials, they are testing whether proton or photon-based therapies better protect patients’ cognitive skills. These trials will show us how we can better preserve brain function and improve patients’ quality of life.