What is MR guided radiation therapy?

MRgRT (Magnetic Resonance guided Radiation Therapy) is a new and innovative radiation treatment option that is great for moving tumors and surrounding healthy organs. It allows your clinical team to see your tumor and surrounding anatomy in incredible soft-tissue quality before treatment, and in real-time during treatment. This allows the cancer treatment to be adapted precisely to suit your anatomy in every session, which aims to reduce side effects and the number of treatment sessions you need to attend.^{1, 2, 3}

Unlike other cancer radiation therapies, MRgRT combines the imaging capabilities of an MRI scan with radiation therapy to deliver treatment that is tailored to you. This means that doctors can see tumors that couldn’t be seen before, in a much clearer way. ^{1, 2} It also means that your clinical team will be able to react to how your tumor responds to therapy and improve your treatment accordingly to kill cancer cells.

A Linear Accelerator (also known as a Linac) is a dedicated cancer treatment machine that produces high energy X-rays to deliver radiation in order to treat cancer cells. Linacs will typically utilize image-guided radiation therapy (IGRT), which uses frequent imaging during a course of radiation therapy to ensure treatment precision and accuracy. These pictures are typically made using integrated CT (Computed Tomography). IGRT is particularly helpful when treating tumors in areas of the body prone to movement, as well as for tumors located close to important organs and healthy cells. Some internal anatomies require small markers to be implanted before treatment to help to see the location of the structure of interest on the images.

An MR-Linac is also a dedicated cancer treatment device, but it is integrated with a magnetic resonance imaging scanner (MRI). This type of Linac provides direct, clear views of internal organs, tissues and other structures both before and continuously throughout your treatment. MRI imagers unlike x-rays and CT, do not produce ionizing radiation. MRI pictures are created by generating a magnetic field and radiofrequency waves which are forms of non-ionizing radiation. The images allow the clinical team to see incredible detail in three-dimensions, which gives them great insights to better tailor the treatment to you. There is also no need for implanted markers.

The experience is very similar to an MRI (magnetic resonance imaging) scan, there’s no sensation associated with the radiation. You will not be able to feel the radiation or magnetic field. The couch is fairly soft, and pads are put around the arms and legs to make sure you stay comfortable and in position. You will have earplugs or earphones should you wish to listen to music. The machine can be adapted for whatever position you are in. You will always be able to communicate with the radiation therapist.

A lot of careful design has gone into the MR-Linac to make it as comfortable, open and calming as possible. This includes a ‘wide-bore’ with a special ‘flare opening’ so there is space around you, and the system is well-lit, short and open on both ends.

Average MR-Linac and MRgRT treatment sessions range from 20–45 minutes. Your doctor will tell you how many treatment sessions you will need.

The technology allows the clinical team to see your tumor and surrounding organs at the time of treatment, targeting your cancer more effectively.^{1, 2} Your tumor’s size, shape and location will change throughout treatment. MRgRT allows doctors to react to those changes and the way your tumor is responding to therapy. The radiation treatment dose delivers controlled high-energy X-rays which destroy cancer cells or damage them, which aims to stop them from growing or spreading.

MRgRT is currently used to treat a wide variety of indications (more than 40) such as prostate, liver, rectum, pancreas and lymph nodes. The MR-Linac is extremely accurate at targeting small tumors and it’s also beneficial in the treatment of metastases, where cancer has spread to other parts of the body. MRgRT is also beneficial if a cancer patient requires repeated treatment to areas that have previously received radiation therapy.

This therapy helps to guard your healthy organs against unwanted exposure to radiation which can mean you may experience fewer side effects compared to other treatment options. ^{1, 2} By delivering a more targeted dose of treatment, this therapy can also result in the need for fewer treatment sessions overall.³

Yes, adaptive radiotherapy enables the treatment to be changed, or adapted, to respond to a signal that additional information is known about you or that internal organs have changed shape or position from the original state at the time of planning. A tumor’s shape, size and location can change during the course of treatment.

MRgRT allows your clinical team to see your tumor and surrounding anatomy with magnetic resonance imaging (MRI). This provides super soft-tissue images compared to current standard CT and X-ray-based technologies without additional radiation exposure. The MRI images are taken before the treatment and continuously during the treatment (in real-time), which means treatment can be adapted to fit your anatomy and it allows the clinical team to watch your tumor as they treat it.

More than half (about 60%) of people with cancer have radiation therapy. Radiation therapy has been used to successfully treat cancer patients and kill cancer cells for many years, and advances have been made to ensure that it is safe and effective. MRgRT guards your healthy organs against exposure to radiation, which can mean you may experience fewer side effects compared to other treatment options.^1,2 Your doctor will check and update your therapy throughout your treatment.

Although there can be side effects to any radiotherapy treatment, the most common side effects of radiation therapy are typically temporary and will vary depending on which area of the body is being treated. Please be sure to talk to your doctor about any concerns or discomfort you may have during or after your treatment.

Radiation recovery is individual to you, your age, and the type of cancer being treated. Most patients will be able to carry out everyday activities during and after treatment. The most common side effects of radiation therapy such as fatigue are temporary and will typically resolve within a few weeks. Even though radiation treatments only target specific cancer cells, there are small amounts of healthy tissue that feel the effects of radiation, which is why your treatment is carefully planned and scheduled. Most cells recover within a few weeks, but very rarely some effects can develop later or require a longer recovery process. Your doctor will make sure you are aware of all possible effects at your consultation.

Your doctor will help you decide which treatments could be best for you.

We know that going through treatment can be stressful. It helps to be informed, so please find below a list of questions you may want to ask your doctor at any stage during your treatment:

• Is MRgRT the best treatment for my type of cancer?
• How will the radiation therapy be given?
• How many treatment sessions will I receive?
• Are there alternatives to MRgRT treatment?
• What are some of the support groups I can turn to during treatment?
• If I have questions after I leave, who can I speak to?
• How can I expect to feel during treatment and in the weeks following treatment?
• Will I be able to continue my normal activities during and after treatment?
• What side effects may occur from the treatment and how are they managed?
• Do I need a special diet during or after my treatment?
• After my treatment is finished, do I need to return for check-ups?

MRgRT (Magnetic Resonance guided Radiation Therapy) and MR/RT (Magnetic Resonance Radiation Therapy) are both terms that may be used to describe this new and innovative cancer treatment option that allows doctors to watch your tumor as they treat it. The MR-Linac is a dedicated treatment device used to deliver MRgRT.^{1, 2, 3}