The Science of Proton TherapyFAQs
Frequently Asked Questions
- What's a proton?
- How does proton therapy work?
- What is a cyclotron?
- What's the difference between proton radiation and traditional X-ray radiation?
- Is proton therapy experimental?
- Is proton therapy covered by insurance?
- Why aren't more physicians familiar with proton therapy?
- What types of cancer can proton therapy treat?
- Can proton therapy be used for children with cancer?
- How does proton treatment work?
- What kind of success has proton therapy had?
- Are there side effects?
- How do I contact MPRI?
What's a proton?
Protons are charged particles that possess a well-defined range of penetration determined by both the proton beam's radiation and the density of the tissue through which it passes. Like X-rays, protons can be used to destroy cancer cells, but proton radiation can be more precisely guided, making proton therapy an optimal treatment for localized tumors, cancers near vital organs, and pediatric cancers.
How does proton therapy work?
Proton therapy uses the protons from hydrogen atoms that are left after the electrons are removed. A cyclotron or synchrotron is used to accelerate the protons, then sends them through a beam transport system to individual treatment rooms, where they are used to treat tumors.
As each proton enters the body, there is a low dose of radiation released at the surface and a sharp burst of radiation released as the proton nears the end of its range. This is called the Bragg Peak, and it can be placed at a specific depth in the tissue so the radiation hits exactly where needed and leaves the healthy tissue beyond the tumor unaffected. The proton beam can even be contoured to the shape of the tumor, further decreasing radiation exposure to healthy cells and limiting side effects.
What is a cyclotron?
A cyclotron is a circular particle accelerator in which hydrogen particles are accelerated and protons are extracted to create a proton beam. Higher velocity synchrotrons are also used at some proton treatment centers.
What's the difference between proton radiation and traditional X-ray radiation?
Traditional X-ray radiation affects everything in its path, so doctors often limit the radiation dose to minimize damage to critical organs. X-rays also continue to pass through the body after reaching the tumor, affecting the healthy cells beyond it.
Proton radiation therapy achieves greater precision while providing a lower dose of radiation to healthy tissues. This advantage allows higher doses to be delivered to the tumor with a lower risk of hurting healthy cells.
Is proton therapy experimental?
No. Proton therapy is not experimental. It is an established cancer treatment recognized by government and regulatory agencies.
Is proton therapy covered by insurance?
Proton therapy is covered by Medicare and most private insurance carriers. It is also covered by Medicaid in many states, including Indiana. MPRI's financial advisors are dedicated to working with you and your insurance provider to help you obtain coverage or authorization.
Why aren't more physicians familiar with proton therapy?
Although proton therapy has been used in the U.S. for more than 30 years, recent advances in computer-assisted treatment systems and imaging technologies, such as CT imaging, MRIs, and PET scans, have enabled technicians to precisely plot tumor locations, allowing the proton beam to work to its full potential. Additionally, to produce a proton beam, a treatment facility must have a particle accelerator (such as a cyclotron or synchrotron). Because particle accelerator construction is very expensive, proton therapy is currently offered in only a few treatment centers around the U.S. As new proton facilities are built, more physicians will become familiar with this therapy and recommend it for their patients.
What types of cancer can proton therapy treat?
Proton therapy is most effective for localized tumors or cancers that are located near a vital organ. Metastasized cancers, or cancers that have spread throughout the body, may benefit from X-ray therapy, chemotherapy, or a combination of other treatments. Click here for a list of cancers currently being treated at MPRI.
Can proton therapy be used for children with cancer?
Yes. Proton therapy is highly effective for treating pediatric cancers because it doesn't damage healthy growing bone and tissues, allowing children to develop normally and reducing the risk of secondary tumors later in life.
How does proton treatment work?
Treatments are usually given five days a week, for a period of 6 to 8 weeks. The actual proton beam time is about one to two minutes, but total daily treatment time can range from 30 minutes to an hour due to the time spent carefully positioning the patient. For more information on the treatment process, see What to Expect.
What kind of success has proton therapy had?
Proton therapy has increased cure rates in several cancers, reduced short- and long-term side effects, and reduced the risk of secondary tumors among children as they grow up. It is the most precise form of radiation currently available to treat cancer patients.
According to several research studies, proton therapy has achieved promising results:
- Studies conducted at Loma Linda University Medical Center over the past 5 years show that the overall disease-free survival rate of proton therapy patients with prostate cancer has reached 89 percent, and patients have fewer side effects than with traditional treatments.
- With the use of proton therapy, 10-year cure rates for patients with tumors at the base of the skull have increased from 35 percent to 75 percent.
- The five-year control rate for patients with paranasal sinus tumors has increased from 25 percent to 85 percent.
- Of 1,351 patients with uveal melanoma treated with protons in Villigen, Switzerland, the 10-year actuarial local tumor control rate was 96 percent and the eye retention rate was 94 percent.
Are there side effects?
Depending on a patient's age, medical history, and condition, he or she may experience minor side effects. Some patients experience fatigue, skin irritation, or slight hair loss.
How do I contact MPRI?
Please contact us for more information about MPRI or to refer patients for treatment.