Proton Beam Therapy

The S. Lee Kling Proton Beam Center at Siteman Cancer Center. The S. Lee Kling Proton Beam Center at Siteman Cancer Center.

The S. Lee Kling Proton Therapy Center at the Siteman Cancer Center is the only proton therapy center located within a 240-mile radius of St. Louis.

The center houses two proton units: the world’s first compact proton beam accelerator, called the Mevion S250™ Proton Beam Therapy System, as well as a second unit equipped with pencil-beam scanning technology.

Radiation oncologists and physicists here helped evaluate the original system, the Mevion S250, and developed the patient protocols and quality standards for this advanced proton treatment technology.

Both systems allow for extremely precise adjustments to the radiation beam, so physicians can precisely target tumors while minimizing damage to surrounding tissue.

Proton beam therapy’s main advantage is that proton radiation specialists can control radiation beams by:

  • Depth
  • Shape
  • Amount of radiation dose

In other external radiation therapies, radiation beams pass through a patient to a defined location and then exit the body on the other side, leaving deposits of radiation all along their path. Because proton radiation therapy allows for depth control, the majority of radiation is held until the proton beams hit the precise area targeted. Little to no radiation is delivered past the tumor.

Proton therapy cancer treatment can be used as a solo treatment option or it can be used in combination with other radiation therapies or chemotherapy.

There are only a handful of proton beam therapy centers in the United States, most with large, football field-sized treatment areas. In contrast, the Mevion S250™ system, called a superconducting synchrocyclotron proton accelerator, is much more compact, fitting into about 2,000 square feet. The compact nature of the technology makes it more versatile as well as more cost-effective to use.

The Mevion S250 system, which debuted in late 2013, is ideal for patients with solid tumors that are located near sensitive structures or tissues, such as the eyes, brain or spinal cord. It is particularly beneficial for children, where precise targeting is critical to avoid impacting growing bones or tissues. St. Louis Children’s Hospital and the Siteman Cancer Center are committed to providing proton beam therapy in a way that is sensitive to the needs of children and their families.

Pencil-beam scanning technology

This technology is the most advanced form of radiation therapy available, as it delivers extremely precise treatments of proton therapy.

Installation of this second unit began in early 2019 and was completed in June 2020.

“Pencil-beam scanning helps us provide patient-specific care for adults and children, particularly those who have especially complicated cases,” said Stephanie M. Perkins, MD, director of the Proton Therapy Center and an associate professor of radiation oncology at Washington University.

Pencil-beam scanning delivers proton therapy in a single, narrow proton beam aimed directly at the tumor and adjusted for intensity. The beam then “paints” the radiation dose onto the tumor.

Our Comprehensive Cancer Team

Our team of proton beam therapy experts includes:

Radiation Oncologist – The medical specialist who oversees your entire care and prescribes the length and dose of treatment.

Medical Dosimetrist – Works directly with the radiation oncologist to implement the cancer treatment plan by mapping out the dosage parameters around your tumor and the precise angles and depth of the proton beams.

Medical Physicist – Oversees the actual delivery of proton beam therapy, ensuring the accuracy of the proton beam.

Proton Beam Therapy Nurse – A nurse with advanced training in caring for both adult and pediatric patients who undergo proton beam therapy.

Radiation Therapists – Your guides into the proton therapy treatment room and will assist in positioning you correctly on the proton beam therapy treatment couch. They will also take X-rays to ensure the accuracy of your position prior to the start of treatment and will remain with you during your entire treatment session.

Anesthesiologists and Nurse Anesthetists – For patients, particularly children, who need sedation during proton beam therapy, both a dedicated proton beam anesthesiologist and a nurse anesthetist who are highly skilled at caring for infants and children are on site.

What to Expect

  • Simulation: Prior to your first treatment, you will be asked to come to the Department of Radiation Oncology on the lower level of the Center for Advanced Medicine to undergo a CT scan and/or x-rays to initially develop your treatment plan. You will be placed in a large bore CT scanner so that we can accurately map out your tumor location and the parameters for treatment dosage.
  • Immobilization Devices: A head mask or body mold will be created prior to your first treatment to make sure your head or body stays in position during treatment. Once that is complete, you will be scheduled for a series of proton beam therapy treatments in the S. Lee Kling Proton Therapy Center, conveniently accessed on the street level of our adjacent North Parking Garage at 224 S. Euclid Ave.
  • Proton Therapy Treatment: Treatment sessions are once a day, five days a week for an average of 20 to 40 sessions (every weekday for about a month and a half). Your doctor may order a shorter or longer series of treatments depending upon the type and location of your cancer. Each treatment session averages 30 minutes, although some may last as long as an hour.
  • Anesthesia: Proton beam therapy does not hurt but in some cases anesthesia may be required for minors to minimize movement.

Frequently Asked Questions

How long does the radiation remain in my body?

Proton radiation, once delivered to the targeted tumor site, has a very short life. After you complete treatment, you can leave the treatment room without any risk or radiation exposure to others.

Is proton therapy experimental?

No, proton therapy is neither experimental nor investigational. It has been used in the United States for more than 50 years and in a hospital setting since 1990. It is an established form of treatment that is widely accepted by physicians, government agencies and many insurers.

Can proton therapy be used in conjunction with other forms of cancer treatment?

Yes. Depending on the case, proton therapy may be used in combination with traditional radiation, chemotherapy and/or as a follow-up to surgery. What are the side effects from proton therapy? Minimal to no side effects, compared to conventional forms of radiation. Much more easily tolerated than standard radiation therapy.

What kinds of tumors are best treated by proton therapy?

Tumors that are localized and have not spread to distant areas of the body.

Directions to the S. Lee Kling Proton Therapy Center

Parking: Convenient self-parking on the Washington University Medical Center campus is available in the Euclid Garage, located at 224 S. Euclid Ave. Valet parking also is available directly outside of the Center for Advanced Medicine, right across the street.

Directions from the Euclid Garage to Radiation Oncology in the lower level of the Center for Advanced Medicine (CAM): Take the Euclid Garage elevators to the third floor, cross the walkway link and take the main CAM elevators to the lower level. This will take you to the main Radiation Oncology waiting room.

Directions from the Euclid Garage to the S. Lee Kling Proton Therapy Center: Take the Euclid Garage elevators to the first floor. The entrance to the Proton Therapy Center is to the left.

Contact Information

Department of Radiation Oncology Center for Advanced Medicine
4921 Parkview Place
St. Louis, MO 63110
1-800-221-4336 or 314-747-7236

S. Lee Kling Proton Therapy Center
224 S. Euclid Ave.
St. Louis, MO 63110