Radiation Therapy

Radiation therapy uses high-energy rays or particles to destroy cancer cells. It is usually used to treat brain and spinal cord tumours. Your healthcare team will consider your personal needs to plan the type and amount of radiation, and when and how it is given. You may also receive other treatments.

Radiation therapy is given for different reasons. You may have radiation therapy:

• as your main treatment to destroy the tumour cells when surgery can’t be done, and medicines are not effective
• to destroy tumour cells left behind after surgery to reduce the risk that the tumour will come back (recur) (called adjuvant therapy)
• to treat recurrent brain tumours
• to prevent or relieve the symptoms of brain and spinal cord tumours

 3D-Conformal Radiotherapy (3D-CRT)

• 3D-CRT is the delivery of an individualized radiotherapy plan that is created using three-dimensional imaging. Patients first undergo a specialized planning computed tomography (CT) scan. After which, the radiation oncologist outlines the target tumour(s) and nearby normal organs. The shape of radiation beams are then shaped to match the tumor to make sure all visible disease is well covered while sparing normal organs and tissues as much as possible. When treating the brain, patients wear a custom-fitted plastic mask to prevent patient movement during treatment and ensure consistent set-up between treatments.

Intensity-Modulated Radiotherapy (IMRT)

• IMRT is an individualized, CT-based approach similar to 3D-Conformal Radiotherapy but with a more sophisticated treatment planning and delivery process. A higher number of beams, beam angles and the ability to change the shape of the beams during treatment allow for more precise radiotherapy. This type of radiotherapy does a better job of matching the tumour shape and sparing normal tissues.

Volumetric Modulated Arc Therapy (VMAT)

• VMAT is a type of IMRT treatment approach but with an added level of complexity. While the radiation treatment is being delivered, the arm of the radiation delivery machine moves in one or more arcs around that patient at the same time while the radiation beam shapes are changing to match the tumour. This allows for faster treatment delivery and additional beam angles to work with.

Stereotactic Radiosurgery (SRS)

• Is the delivery of precise, high dose radiotherapy to one or more tumours in the brain typically in 1-5 treatments. The precision of this technique allows higher doses of radiation to be delivered just to the tumours, allowing for maximum sparing of normal brain tissue. This requires sophisticated immobilization techniques to ensure the head does not move during treatment and is in the same position for each treatment if more than 1 treatment is planned.

Radiation Treatment Machines

Linear Accelerator (LINAC)

• LINAC is the most common type of radiation treatment machine and can be found in every radiation treatment centre in Canada. It can treat the brain or body using a 3D-CRT, IMRT, VMAT or SRS technique. There are variations between these machines depending on the manufacturer and model.

CyberKnife

• CyberKnife is a radiation treatment machine manufactured by Accuray Inc. that includes a LINAC mounted on a robotic arm that can track tumor and patient motion in real-time and make adjustments to improve accuracy. It can treat the brain or body using a 3D-CRT, IMRT or SRS technique.

GammaKnife

• GammaKnife is s a radiation treatment machine manufactured by Elekta that can deliver up to 200 beams onto a target to achieve very precise and high dose radiotherapy. It uses a SRS technique and is only used to treat the brain. A few common indications for the GammaKnife include brain metastases, vestibular schwannomas, atriovenous malformations and functional conditions like trigeminal neuralgia. Older models required patient immobilization with a frame attached to the patient using 4 invasive pins. The most recent model allows for immobilization with a non-invasive mask and can also track patient movement during treatment.

MR-LINAC

• MR-LINAC is a novel radiation treatment machine that is comprised of a LINAC with a built-in magnetic resonance imaging (MRI) device. This allows for image-guided radiation treatment delivery using MRI, which provides the most detailed picture of the brain. These images can be used to adjust radiation coverage prior to each treatment to maximize accuracy. The first patient in Canada was successfully treated using an MR-LINAC in August 2019 at the Odette Cancer Centre, Sunnybrook Health Sciences Centre in Toronto.

Complementary and Alternative Medicine (CAM)

Complementary therapies are products and practices used along with conventional medical treatment. Alternative therapies are treatments used instead of conventional treatment. If you choose to use a CAM therapy or a CAM practitioner in conjunction with your treatment plan, it is important to tell your health care team. Knowing all the therapies you are using, including CAM, allows your health care team to provide care that is comprehensive and safe.

Clinical Trials

Clinical Trials have allowed the medical community to improve treatments and the quality of life of patients everywhere. Clinical Trials may be evaluating a completely new way of treating brain tumours, may be developing different ways to administer an existing treatment or looking at new combinations of drugs. This is all done with a focus on improving the quality of life for those affected. Clinical trials may not yield favourable results, but with each trial, important questions may be answered and progress is made.

Participation in clinical trials is voluntary. Your oncologist or surgeon may approach you about participating, or you can ask your health care team if a clinical trial is open or expected to open for someone in your situation.