Many people are familiar with the idea of radiation therapy for treating brain tumors, but what you may not realize is that there are several different forms of radiation treatment. One method is Gamma Knife®, a form of stereotactic radiosurgery, which has been used and refined over the past 40 years to safely and effectively treat brain and skull base conditions. Another form of radiation treatment is proton therapy, a fairly new option that you may have come across in news articles or while reading online.
To help you better understand the differences between the two technologies, the following information will outline differences between Gamma Knife vs. proton therapy, including the procedures themselves and what they are typically used to treat. Though your doctor will make treatment recommendations based on your individual condition and health factors, having a broad understanding can help you feel more informed about the entire process.
Gamma Knife Radiosurgery Procedure
Gamma Knife is a form of stereotactic radiosurgery, a specialized form of radiation treatment that utilizes 192 individual photon beams to target a very focused area. Despite its name, Gamma Knife does not involve any surgery or incisions and takes place entirely in an outpatient setting. This means there is no hospital stay, no surgical risk, and no lengthy post-operative recovery period.
Because of the precision and accuracy of Gamma Knife, your doctor can use it to treat only the target area, sparing healthy surrounding tissues. As a result, you can expect fewer of the unpleasant side effects sometimes associated with conventional radiation therapy. The treatment itself typically takes 15-60 minutes, and many patients require only a single session. However, should your condition require further therapy, Gamma Knife can be repeated, and it can be used in conjunction with other treatments, such as surgery.
Gamma Knife is typically performed in an outpatient setting and does not require a hospital stay. Many patients will only need a single treatment session, though this depends on each patient’s individual diagnosis.
The procedure itself involves four general steps. First, to ensure the patient does not move out of position during the treatment, a lightweight frame or custom mask is positioned on his or her head. The patient then undergoes a high resolution MRI to establish the size and location of the treatment target. Using this information, the radiation oncologist and neurosurgeon determine the specifications of the patient’s treatment, including target volume, radiation dose and number of treatments.
Once the treatment plan is finalized, the patient undergoes the actual treatment procedure. The frame/mask is positioned on the patient’s head, and secured to the treatment table. The table is moved into position, and the treatment begins. Patients may have a single treatment session or multiple treatments (up to five), depending on their unique condition.
Proton Therapy Procedure
Proton therapy is also a highly specialized form of radiotherapy in which beams of fast-moving particles (protons) are used to treat certain cancers. It has actually been around for many years, however, has gained much attention in recent years as the technology has become more widely available. One of the interesting properties of proton beam therapy and other particle therapies is that when the beam enters the body, it travels and then stops at a defined distance called the Bragg peak. This means that the tissue beyond that distance doesn’t get exposed to radiation. This is particularly advantageous in children with certain cancers where developing parts of the body may be spared from radiation exposure. This is not as beneficial in adults and there is no clear indication for the use of proton therapy in adult patients. Proton therapy is used much in the same way as conventional x-ray or photon based treatments where small daily doses of radiation are delivered over a period of several weeks depending on the disease being treated.
Gamma Knife vs. Proton Therapy
Though they are both forms of radiation therapy, Gamma Knife radiosurgery and proton beam are unique forms of technology and have different features, as outlined below.
Pros and Cons of Both Procedures
There are some similarities between the Gamma Knife and proton therapy as they are both forms of radiation, however, there are key differences in their indications.
|Gamma Knife||Proton Therapy|
|The procedure takes place in an outpatient setting and does not require a hospital stay.||X||X|
|You are awake during the procedure.||X||X|
|Delivers less radiation to surrounding tissues compared to whole brain radiation.||X||X|
|Noninvasive procedure that doesn’t require any surgical incisions.||X||X|
|Can treat delicate areas within the brain with sub millimeter precision.||X|
|Indicated for the treatment of metastatic brain tumors.||X|
Side Effects of Both Procedures
The side effects of Gamma Knife radiosurgery and proton beam therapy relate to factors such as the area being treated and the size and frequency of your dose. Side effects can include:
- Nausea and vomiting
- Irritation at the administration site
- Delayed swelling in the months following treatment
Recovery Time for Both Procedures
Because Gamma Knife radiosurgery and proton beam therapy are not surgical procedures, there is virtually no recovery time. Patients can return to their daily activities within a day or so of treatment. However, because proton beam therapy can require weeks of treatment, there can be a stretch of time before you begin recovering, effectively lengthening the overall recovery period.
Gamma Knife Advantages
The advantages of Gamma Knife vs. proton therapy are related to the advanced technology of Gamma Knife and the way it delivers treatment to the target area. With proton therapy, there are some difficulties associated with the ability to precisely predict the exact stopping point of the particles due to a process called “range uncertainty,” resulting in potential for greater radiation dose to immediately neighboring healthy tissues.
The photons that Gamma Knife treatment utilizes, however, deposit their radiation dose in a much more predictable manner and are able to precisely target tumors in very sensitive locations with unparalleled accuracy and precise control of a concentrated radiation dose to single or multiple tumors.
Other advantages of Gamma Knife vs. proton therapy include:
- Research: Until recently, proton therapy has been limited to just a few medical centers, so it doesn’t have the years of proven research and results that Gamma Knife treatment does.
- Availability: Proton therapy isn’t widely available, which could delay treatments and/or require lengthy travel for some patients.
- Metastatic Tumors: Gamma Knife can be used to perform radiosurgery where few treatments of focused high dose radiation are delivered to treat multiple small tumors within the brain that have spread from other locations with excellent sparing of normal brain. Proton therapy has not been shown to be feasible in this situation due to the relatively larger volumes of normal brain that would have to be treated to high doses of radiation.
Gamma Knife vs. Proton Therapy for Brain Tumors
While both Gamma Knife radiosurgery and proton beam therapy can be used to treat brain tumors, only Gamma Knife can reliably be used to perform highly focused treatments such as stereotactic radiosurgery. The brain is an incredibly delicate organ, requiring a high degree of precision when treating brain tumors. Only the Gamma Knife possesses the accuracy required to treat multiple conditions such as metastatic brain tumors and benign conditions. The Gamma Knife system has been proven through decades of research as an excellent treatment option for many patients with brain tumors. This is why the team at The Valley Gamma Knife Center has chosen the Gamma Knife system over proton beam therapy for treating its patients.
The Right Treatment for You
Gamma Knife radiosurgery has been used to treat over 1 million patients worldwide for conditions of the brain and skull base. With its superior technology developed specifically for treating these conditions, the Gamma Knife system offers the highest accuracy on the market as compared to other available radiation therapy technologies.
If you still have questions about the differences between Gamma Knife vs. proton therapy or why your doctor has recommended one treatment over the other, be sure to bring them up at your next appointment. He or she will be glad to discuss the factors taken into consideration when developing your treatment plan to ensure you are comfortable with your upcoming treatment.