TEXAS REGIONAL MEDICAL TECHNOLOGY CENTER
As part of a settlement agreement between the U.S. Department of Energy (DOE) and
the State of Texas, DOE proposes to transfer $65 million of federal funds to the
Texas National Research Laboratory Commission for construction of the Regional
Medical Technology Center (RMTC), to be located in Ellis County, Texas.
The RMTC would be a state-of-the-art medical facility for providing proton cancer
therapy. The RMTC would be operated by the State of Texas in conjunction with the
University of Texas Southwestern Medical Center. The Center would take advantage
of the linear accelerator assets of the Superconducting Super Collider (SSC) to
accelerate protons (the positively charged particle in a hydrogen atom) to high
energies. Accelerated protons would be used for the treatment of cancer patients
at the site. DOE's role in the proposed action is limited to providing the $65
million contribution.
Cancer therapy with a proton beam.
Project Purpose: Proton Cancer Therapy.
Each year, more than 1 million Americans are diagnosed with cancer, and by 1999
more than 90,000 cases will be seen each year in Texas alone. Some cancer deaths
can be prevented by destroying the cancer at its origin.
A common and often effective form of therapy is to attack the cancer with beams
of radiation, such as x rays, gamma rays, or neutrons. With these types of
radiation therapy, however, the radiation dose is greatest near the surface of
the patient's body, and the dose decreases the further it penetrates. As a
result, the healthy tissue in front of a deep-seated cancer tumor will receive a
larger dose of radiation than the tumor itself, and the healthy tissue behind
the tumor can also receive a significant dose. This unavoidable damage to healthy
tissues often causes serious side effects during radiation therapy, and it
generally reduces the usefulness of such therapy for the treatment of cancer,
in spite of its effectiveness in destroying the cancer itself.
In contrast, the treatment of cancer using proton beams has a significant
advantage. When a beam of protons is accelerated to high energy and directed at
a tumor, the protons gradually slow down, releasing a modest radiation dose to
the area near the surface of the body. Then, when the protons are moving very
slowly, the radiation dose increases rapidly until the protons come to a complete
stop. This increased radiation dose is called the "Bragg peak" named for the
discoverer of this effect. Because proton beams can be specifically tailored to
each patient by beam-shaping devices, an effective dose of radiation is delivered
primarily to the tumor, and healthy tissues can largely be spared (Figure 1).
This ability to deliver the radiation dosage primarily to the diseased area makes
proton therapy an extremely precise form of cancer treatment. This precision is
especially desirable when a tumor is located near a critical organ such as the
brain or spinal cord.
The Site of the RMTC.
Project Description: Proton Accelerators. The linear accelerator that was planned as the proton beam injector for the SSC had been partially completed before the SSC project was terminated. As part of the termination settlement between the United States and the State of Texas, $65 million of federal funding will be provided for incorporating part of the linear accelerator and its associated assets into a medical facility that will be known as the Regional Medical Technology Center. The Center will use these existing assets in a proton therapy complex.
The completed portion of the SSC linear accelerator, along with a segment that has almost been completed, will be used to inject the linear accelerator beam into a new proton synchrotron, a type of circular accelerator designed to provide a high-energy proton beam. The high-energy beam from the synchrotron will then be transported through a sophisticated system of magnets, instruments, and beam-shaping devices so that it can be focused to the exact needs of the cancer patient. The energy of the proton beam provided by this system can be as high as 350 MeV (million electron volts).
Buildings: The existing SSC Linear Accelerator building will house the injector for the proton therapy synchrotron. The injection beam will be transported from the injector to the synchrotron via a new tunnel, and the synchrotron itself will be located in a new multi-story building that will also house the patient treatment areas of the Proton Therapy Facility. Substantial clinical areas in this new building will be used for diagnostic imaging, treatment planning, patient support, administration, and staff support.
July 1995 lb
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