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New proton therapy facility will offer another tool in treating cancer

Jeffrey Bradley holds a brass aperture for use in proton therapy.
Hilary Davidson | special to the Beason | 2013

This article first appeared in the St. Louis Beacon. - New technology is everywhere these days. Even in the basement of the Washington University School of Medicine’s north parking garage.

There, nestled next to Applebee’s restaurant and the Parkway Hotel, is an unassuming office with a sign in the window: S. Lee Kling Center for Proton Therapy.

Set to open by the end of this year, it is the first proton therapy facility in Missouri. Proton beam therapy is a type of radiation therapy in which targeted proton beams are aimed at a tumor. It is believed to be more precise than intensity modulated radiation (IMRT) therapy, which come from X-rays, making the new technology ideal to use on cancers such as brain tumors, where any error means destroying healthy brain tissue.

This facility differs from other proton facilities around the country in several ways, says Dr. Jeffrey Bradley, S. Lee Kling professor of radiation oncology and director of the Proton Center at Washington University School of Medicine. Instead of being housed in a large facility with three or four treatment rooms, the center has only one treatment room. As second generation technology, its cyclotron is much smaller than the first generation, and costs much less: $25 million compared to the more than $100 million it cost to build the first generation of proton therapy facilities, said Bradley.

The space in the parking garage is ideal, Bradley says, because of its proximity to the Siteman Cancer Center, which will make it easy for physicians to access patients while staying close to Siteman.

“Effectively we look at it like we’re building a treatment unit just 50 yards away,” he said.

The proton center’s proximity also makes it less expensive to staff, he said, and makes sharing resources, such as a CT scanner, possible.

“We basically need 4 therapists, a nurse, and a reception person. We share our resources across the street. We don’t need to buy a CT scanner.”

Small is part of the design, Bradley said.

“A lot of the other proton centers are big, four-room centers and they built them miles away where there was space for that,” said Bradley. “(Then) you have to put together a staff that just works at the proton center.”

With just one treatment room, Bradley said the facility will be able to pick and choose patients who will benefit most from proton beam therapy. Some centers, he said, steer as many patients as possible toward the more-expensive proton therapy to pay for the large facilities.

“We’ll be the first ones, and for now the only ones, to have to choose who we treat.”

The target patients, says Bradley, are patients whose tumors border healthy tissue that is extremely sensitive to radiation, such as pediatric cancer patients, patients with brain tumors, head and neck cancers, cancers around the eyes or the spine, and lung and esophageal cancers.

Citing recent controversy surrounding the higher costs of proton beam therapy, particularly for prostate cancer patients, Bradley doesn’t see proton beam therapy as necessarily better, depending upon the case.

“I don’t happen to think that it’s any better for prostate than IMRT,” he said. “We’ll select (patients) where there’s a clear advantage to protons."


The cost of proton beam therapy at the center will be approximately 40 percent higher than standard radiation therapy, Bradley said. That means that a course of IMRT (standard) radiation costing $20,000 will cost insurers around $28,000.

Some of this additional cost, says Bradley, comes from the instruments used to guide the beam so precisely.

How it works

While the proton beam has accuracy to within 0.1mm, the machine requires brass apertures and tissue compensators to direct it to the unique shape of each tumor.

A brass aperture is a large ring made of brass loaded onto the machine much like a filter is put on a camera lens. The brass aperture, which is custom made for each patient, shapes the proton beam as it’s coming out of the machine. Equally important is stopping the proton beam at the distant edge of the tumor. For this a ring made of acrylic or plastic, called a tissue compensator, is custom made for each patient.

“[The tissue compensator] basically is designed to shape the distal edge (the edge farthest from the center) of the beam to the shape you want. If it’s spherical, you would shape the edge of the beam so that it’s spherical at the distal edge,” said Bradley.

The varying thicknesses of the acrylic or plastic cause the beam to stop at different places. Each aperture costs around $300 to make, one of the factors that drives up the cost of proton beam therapy. If the tumor changes size or shape, new apertures must be made. If a patient receives the proton beam from more than one angle, apertures must be made for each angle. Bradley expects that the cost of making apertures will average about $1,000 per patient.

Bradley believes, by creating a small, lower-cost proton therapy center, Washington University is pioneering the way for other hospitals to offer proton therapy on a smaller scale.

“I think it’s going to revolutionize treatment. By reducing the overall cost of delivering protons, and having a single room system, and making that successful, it will enable other hospitals and other centers to buy these single room units that are less expensive,” he said.