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Gamma Knife Radiosurgery: Before Treatment

Preparing for treatment with a Gamma Knife involves several steps to ensure the procedure is safe and effective. Here’s what to expect before your Gamma Knife procedure. 

Referral and Gamma Knife coordinator 

Gamma Knife treatment is offered by physician referral only. If you have questions about how referrals work or need help with a referral, contact our Gamma Knife coordinator at or complete this form.

Once you’re referred for Gamma Knife treatment, you will meet with our Gamma Knife coordinator to get an overview of the process and start coordinating your treatment. 

Consultation appointment 

The first step in preparing for Gamma Knife treatment is to have a consultation with a radiation oncologist. A radiation oncologist is a doctor who specializes in using radiation therapy to treat cancer and certain non-cancerous conditions.

During your consultation appointment, your doctor will find out if Gamma Knife radiosurgery is the right treatment for you. They will review your medical history and may order more imaging tests that are needed for treatment. The doctor will discuss treatment options with you and help you decide on the next steps.


We use images of your brain to make a treatment plan for your specific needs. In most cases, magnetic resonance imaging (MRI) is needed within 7 days of your scheduled Gamma Knife treatment. 

Simulation and mask-fitting appointment 

Once you and your doctor have decided Gamma Knife treatment is right for you, we’ll schedule your appointment for a custom mask fitting. 

To ensure the radiation is delivered precisely, it’s important that your head doesn’t move during treatment. We create a custom mask that attaches to the treatment machine and helps you stay still. 

As part of this appointment, we also complete a simulation of treatment. This involves taking images while you’re in the mask to find the best position for your head during treatment. When you return for treatment, we will help you get in the same position. 

To prepare for your mask-fitting appointment, you should: 

  • Take all your medicines as you normally do
  • Avoid wearing any jewelry or makeup
  • Eat a light meal the morning of your appointment
  • Wear comfortable clothing that does not have a hood or collar
  • Remove any facial hair such as beards, mustaches or goatees
  • Avoid wearing clips, pins, bands, braids, wigs or other hair accessories 
  • Avoid using any hair products such as hairspray or gel 
  • Let your doctor or Gamma Knife coordinator know if you’re uncomfortable with tight spaces 

When you come in for your mask fitting and simulation, here’s what to expect: 

  • Your care team will help you lay on the treatment table. We use specialized equipment and cushions to support you and make you comfortable.
  • The mask is made of a lightweight material that’s flexible when heated. While the mask is warm, it will be placed over your face with an opening around your nose. As it cools, the plastic will mold to fit your face. 
  • This process is painless, and you will be able to breathe freely. The mask has an opening for your nose. 
  • After the mask has cooled, it will hold your head securely in place. Then you will have a scan on the machine in the mask. These images will be used to create your personal treatment plan. 

Treatment planning

Over the next few days, the radiation team will use a special computer program to develop your custom treatment plan. They will use the pictures from the MRI to plan where to aim the radiation beams. The computer program uses advanced technology to maximize the safety and accuracy of your radiation treatment. 

The team will also figure out how many Gamma Knife treatment sessions you need. Typically, patients receive 1 to 5 treatments. 

Your treatment plan will be completed before your procedure begins. Your doctor will review it with you, so you know what to expect.