The Proton Therapy Center at The University of Texas MD Anderson Cancer Center
MD Anderson Backgrounder 03/14/06
Inside a tunnel of enormous magnets about the length of a football field in Houston, Texas, a beam of protons rockets towards its objective. Within fractions of seconds, these supercharged sub-atomic particles, stripped from the nucleus of hydrogen atoms and accelerated to the energy of upwards to 250 million volts, strike their target with lethal precision. The damage is done but with a healing effect. We are inside the Proton Therapy Center at The University of Texas
MD Anderson Cancer Center and the target of the proton beam is a malignant human tumor.
For more than half a century, the idea of using accelerated protons to treat cancer has been gestating in the minds of visionaries and evolving in the laboratories of physicists and medical scientists around the world. Now, within The Institute for the Early Detection and Treatment of Cancer at MD Anderson, the idea is becoming a reality. With the advent of the MD Anderson Proton Therapy Center, advanced technology takes hospital-based proton therapy to the next level, giving an unprecedented number of cancer patients access to a therapy more precise in destroying cancer cells without the debilitating side effects of previous radiation treatments.
The story of how the Proton Therapy Center grew from vision to reality is complex and multi-faceted, comprising chapters on medicine, physics, engineering, computer science, philanthropy and finance, as well as hydrology, geology, precision machining, industrial design and construction management. (See below for more on some of these disciplines). And the story is populated by an inspiring cast of characters, from children and manufacturing experts in Japan, to doctors and scientists and even firefighters and police officers in Houston.
But above all, this is a story of how MD Anderson continues to fulfill its mission to eliminate cancer in Texas, the nation and the world, and how it brings new hope for patients by "Making Cancer History."
Proton Therapy: A Critical Tool for Clinicians; Profound Benefits for Patients
The $125 million Proton Therapy Center at MD Anderson will be the largest and most sophisticated of its kind in the world. From the synchrotron for accelerating protons at one end of the facility to the 35-ft.-diameter, 190-ton gantries each capable of directing proton beams with sub-millimeter precision at the other, the facility comprises more than 94,000 square feet of space.
Proton therapy derives its advantage over traditional forms of radiation treatment from its ability to deliver radiation doses to a targeted tumor with remarkable precision within one millimeter that avoids the surrounding tissue, generates fewer side effects and improves tumor control. The twin goals of controlling disease and minimizing side effects are the classic aims of radiation treatment; protons enhance the opportunity for both.
Traditional X-Ray radiation treatment, although effective, is often constrained by the radiation tolerance of the normal tissue surrounding a tumor it is difficult to destroy tumor cells without destroying healthy cells nearby.
With proton therapy, however, the beam enters the body with a low dose of radiation, which increases when the beam, directed by a radiation oncologist, nears its target tumor. The radiation oncologist can precisely target where the protons stop and deposit their radiation dose. The combined effect is greater precision in targeting the tumor with a more potent dose of radiation. This means that doses can now be prescribed on the basis of how much radiation is needed to destroy a tumor, rather than a calculation of tolerance to radiation in the normal surrounding tissue.
For the oncologist, proton therapy provides other advantages. Twenty minutes after a proton treatment, the patient can undergo a PET (Positron Emission Tomography) scan, which will note the precise track of the proton beam through the body to the targeted tumor and enable the clinician to actually watch the cancer cells die.
From the treatment of its very first patient, every patient treated at the Proton Therapy Center will be placed on one of more than 30 new protocols related to tissue toxicity and optimal tumor dose to answer critical cancer questions and advance the science of proton therapy. This presents a unique opportunity to confirm the effectiveness of proton therapy as an adjunct to conventional therapy or in place of current treatments.
The benefits for patients are equally remarkable. Overall clinical benefits of proton therapy include a more targeted, higher volume dose, shorter treatment times, reduced side effects and increased treatment options for many different types of cancer. The Center will be able to provide proton therapy for more patients and more distinct disease sites. A few of the many patient groups who will benefit from proton therapy include:
Children: In general children are more sensitive than adults to the adverse effects of radiation. Proton therapy, when used to treat tumors, can minimize the amount of healthy tissues exposed to radiation, and is therefore very suitable for children. At MD Anderson, the majority of children requiring radiation therapy for their tumors will be treated with proton therapy.
Lung Cancer Patients: When treating lung cancer, radiation oncologists face a significant challenge in avoiding damage to normal, healthy tissue. Some patients have very little lung function, so saving as much normal tissue as possible is crucial. By pinpointing the radiation, there likely is an improved chance of sparing healthy tissue.
Patients with Cancer of the Head and Neck: Surgical treatment of head and neck tumors almost always involves radiation therapy to help ensure all cancer cells are killed. Yet radiation therapy has undesirable side effects, so organ preservation is a primary goal in these cases. Using proton therapy, radiation oncologists can provide heavy doses without increasing toxicity outside the immediate tumor area. For example, patients with salivary gland tumors who receive conventional radiation therapy almost always have lasting side effects, but proton therapy may help avoid them. Similarly, for brain stem tumors, a pencil-beam scanning nozzle will deliver a single proton beam of the narrowest possible dimension, sparing any of the delicate surrounding brain stem tissue.
Prostate Cancer Patients: 65 percent of all prostate cancer patients can be treated precision-targeted, high-dose proton beam therapy, sparing the rectum and bladder, and leaving both urological and sexual functions intact.
Cancers of the Eye: Proton therapy's efficacy in cancer treatment was first demonstrated in ocular melanoma. The control of the proton beam enables physicians to successfully treat cancers of the eye, while preserving the patient's eye and vision. Specially designed patient chairs, or "couches," will position the patient in front of a fixed proton beam during treatment for ocular melanomas.
Bringing a Vision to Life
Although the precision and therapeutic potential of the proton beam has been known for decades, applications were initially limited to a few disease sites. Earlier accelerators were not designed to treat patients due to limited range of energies and reliability; further, many tumors could not be visualized with sufficient precision for effective treatment and safety. It was not until 1961 that the first proton beams were directed at cancerous tumors. Then, beginning in the late 1970s, imaging modalities, including computed tomography, magnetic resonance imaging and positron emission tomography, greatly advanced the diagnosis and visualization of cancerous tumors, thus giving physicians the ability to precisely map the location of tumors. This made proton therapy more practical.
MD Anderson was the vanguard of radiation oncology more than half a century ago, when its scientists developed the first machine to use the radioactive material cobalt-60 and paved the way for more effective radiation therapy around the world. The institution continues to drive advances in radiation science and its team includes two of the world¡¦s leading practitioners.
James Cox, M.D., professors and head of the Division of Radiation Oncology and his wife Ritsuko Komaki, M.D., professor of radiation oncology at MD Anderson had been monitoring the advances in proton beam technology and recognized the enormous potential for patients. The two were to play key roles in the creation of the Proton Therapy Center, which would be the Department of Radiation¡¦s latest contribution to MD Anderson's legacy of innovation.
Transforming the Power of Radiation
Born and raised in Japan, Dr. Komaki had witnessed firsthand the destructive power of radiation after the bombing of Hiroshima. Although her family had left Hiroshima before the bombing, they returned shortly after to care for Komaki's grandmother, who had survived the blast. When a close childhood friend of Dr. Komaki died of leukemia brought on by exposure to radiation, Komaki committed to become a doctor and help to save the lives of others. She went on to do so using the very technology that had devastated her country.
Fast-forward more than forty years.
As head of the Division of Radiation Oncology, Dr. Cox would be responsible for overseeing the entire effort from setting in motion Dr. Komaki's vision to equipping the Center with leading-edge technology and in the near future, treating its first patient. Dr. Cox's expertise was pivotal in applying the most-advanced concepts in radiation oncology to MD Anderson's Proton Therapy Center, including the introduction of intensity modulated proton therapy (also known as "pencil beam"), image-guided proton therapy and the concurrent use of molecular therapies with proton therapy.
Working with Drs. Cox and Komaki as administrator for the Division of Radiation Oncology was Mitch Latinkic, who had helped establish the first hospital-based proton therapy center in the United States at Loma Linda University Medical Center in California in 1990. While the technology involved in MD Anderson's would ultimately be far advanced beyond that at Loma Linda, Latinkic's experience provided deep insight and inspiration.
This team embarked on an exploration of all companies with the capability to apply this technology and it soon became clear that the best candidate was Hitachi, which had built high-energy proton accelerators in Japan. In 1998, the team had a breakthrough: As chance would have it, the Hitachi executive in charge of the accelerator project was a former high school classmate of Dr. Komaki. Their relationship would help to overcome the many obstacles involved in constructing the compact particle accelerator and transporting it halfway around the world.
Bringing Together the Right Partners
Before work on the MD Anderson Proton Therapy Center could begin, the matter of financing had to be addressed. Echoing the uniqueness of the center itself, a novel public-private partnership was formed to develop, own and operate the facility, with each partner playing a highly specialized role.
Each of the financial partners has a local connection but global vision, beginning with The Styles Company, a developer of specialized health care facilities, and Sanders Morris Harris, the largest investment-banking firm based in Texas. Following a competitive selection process involving multiple bidders, these two firms had the responsibility to bring together a team that could most effectively finance, build, equip and manage the Proton Therapy Center. The two will also manage non-clinical operations of the facility after it is opened. MD Anderson, which provided a lease on land valued at $2.5 million for the facility, will have full clinical, research and staffing responsibilities. No public tax money was involved in development of the Center.
Among the lead investors in the project are the Houston Police Officers' Pension System and the Houston Firefighters' Relief & Retirement Fund, among the largest municipal pension funds in Texas. That both funds - which have a responsibility to manage assets in the best interests of members and survivors - have provided significant real-estate debt financing and equity investment for the Center is a tremendous vote of confidence in MD Anderson, the technology and the promise it holds for patients fighting cancer.
With major funding in place, the partners turned to finding precisely the right mix of companies that possessed sophisticated technology and knowledge and could work seamlessly with other industry leaders to create a proton therapy center like no other.
In Hitachi, Ltd., and General Electric Company, they found both world leaders in proton therapy systems and medical imaging, respectively, and financial investors. Varian Medical Systems is the world¡¦s leading producer of fully integrated systems of hardware and software products for treating cancer with radiation. IMPAC Medical Systems provides healthcare IT solutions to more than 1,500 institutions worldwide. All of these prestigious companies were eager to lend their expertise to creating this state-of-the-art, fully computer-integrated Center.
Rounding out all of this was a $1.6 million grant to MD Anderson from Houston's Brown Foundation, designated to educate physicians and other clinicians, patients and the public about the uses and benefits of proton therapy, and to subsidize housing and transportation costs for patients who could not otherwise travel to Houston.
Construction on the Proton Therapy Center began in 2003 and, thanks in part to the deep commitment and involvement of its partners, is on schedule to treat its first patient in early 2006. It is expected that this limited partnership will serve as a blueprint for other public universities and private investors to create mutually beneficial entities to further education, research and medical care.
A Best-In-Class Facility
When it opens, the Proton Therapy Center - the first fully computer-integrated one in the world - will stand as an international center of excellence for proton therapy, research and education. Within its 94,000 feet of space the Center will have distinct areas.
The first section or floor of the Center will house eight examination rooms; clinical space; faculty and staff offices; financial and business offices; and a library and conference and education center.
The second area or floor, for patient treatment, will include a simulation suite for CT; PET/CT and MRI imaging capability; exam rooms and additional clinical space. In addition there are anesthesiology work areas, holding and recovery areas; medical dosimetry areas for treatment planning; medical physics work areas; and, physician work areas.
The treatment rooms themselves are perhaps the most impressive aspect of the facility. Three of the rooms will be quipped with giant gantries - three stories tall, 35 feet in diameter, weighing 190 tons and resembling giant ferris wheels - each capable of maneuvering the proton beam to precisely target the patient's tumor. A fourth room will utilize a stationary beam with two treatment areas for irradiating eye tumors and for larger tumors in the body, including tumors of the central nervous system. A fifth room will contain an experimental station; among its expected uses includes NASA's exploration into what effects the impact protons - the most abundant particles in space - and the release of neutrons might have on space shuttle equipment as well as the health, safety and performance of its astronauts.
Advanced Technology to Generate the Proton Beams
The technology used in Proton Beam Therapy system - including a particle accelerator, beam transport and delivery systems and treatment room gantries - has been evolving for more than half a century.
The protons for the beam originate in an injector. They are stripped out of the nucleus of hydrogen atoms and sent to the synchrotron or particle accelerator.
The synchrotron resembles a brightly colored larger-than-life Lego(r) structure, but is actually a ring of magnets about 20 feet in diameter through which protons circulate in a vacuum tube. As the magnetic field in the ring is increased, the energy of the protons is also increased. When the magnetic field reaches the energy value corresponding to a prescribed beam energy, the field is held constant while the protons are slowly extracted from the ring. In one-half second the protons are accelerated to a maximum energy of 250 million electron volts.
From the synchrotron, the proton beam is accelerated at nearly light speed into the beam transport system where bending and focusing magnets guide the beam around corners and focus it to the desired size and as it travels to a specified location within a controlled environment, or vacuum tubes. The computer control system monitors the size, position and intensity of the beam at main points. Variations from the prescribed parameters send messages through the computer network to adjust the beam or trip interlocks that automatically shut it off. Patient safety always comes first.
The beams are delivered into three of the treatment rooms via the [rotating] gantries, or can also be delivered through a stationary port with two branches - one for irradiating eye tumors and the other tumors in the body including tumors of the central nervous system.
Intensity Modulated Proton Therapy (IMPT) or "pencil beam" scanning for proton therapy patients will be used, making it one of a few centers using this technique in the world. IMPT can change the energy of a proton beam at any time to penetrate a tumor at varying depths, offering the most precise form of delivering radiation therapy. Intricate treatment planning systems will program a pencil-beam scanning nozzle, designed especially for the MD Anderson facility, to deliver a single, narrow proton beam (about a centimeter in diameter) that is magnetically swept across the tumor, layer by layer, depositing the radiation dose like a painter's brush strokes, without the need to build beam shaping devices.
The novel application of sophisticated milling machinery and computer technology will enable physicians to precisely replicate the irregular 3-D shape of tumors through customized beam shaping devices used for each patient during the course of their treatment. These devices will be used in the passive scattering nozzles in the Center.
Engineering, Construction and Safety
Faced with enormous engineering, construction and safety challenges, the MD Anderson Proton Therapy Center team enlisted the far-ranging expertise of specialists including geotechnical engineers, hydrologists, architects and computer scientists.
For example, prior to excavation, 85 million gallons of water had to be removed from the ground beneath the building site in order to temporarily remove hydrostatic pressure. Without this removal, the high water table below Houston could potentially cause the building to settle, thus interfering with the precise calibration required for the proton therapy system. The effort effectively lowered the water table by 25 feet, which will be maintained by a system of two large groundwater lift stations that will perpetually remove groundwater from underneath the building and lower the hydrostatic water pressure to protect from the periodic flooding experienced in the Texas Gulf Coast area.
Safety required other special construction approaches and building features. Radiation containment, for example, demanded that two-thirds of the facility be built below ground level with eight-foot concrete walls and 12-foot thick ceilings - much like a submerged iceberg. Had the center been built above ground level, 15-foot walls would have been required. Electrical contractors faced an added challenge in installing fives miles of electrical conduit embedded in the 28,000 cubic yards of concrete that make up those eight-foot thick walls. Multi-tiered, highly computerized, monitoring, safety, and fire-suppression systems (including a 5,400 gallons-per-minute firewater flow capacity) have been designed and installed to ensure the highest level of safety.
Looking to the Future: Research to Benefit Tomorrow's Patients
Every aspect of the new Proton Therapy Center reflects the values and strategies that make
MD Anderson the world's most respected cancer center. Notably, the center will underscore and strengthen MD Anderson's multidisciplinary approach to patient care and its commitment to translational research.
With the advent of the Proton Therapy Center on MD Anderson's campus, a powerful new tool will be integrated into MD Anderson's holistic approach to patient care. MD Anderson has pioneered the design and management of a multidisciplinary approach covering all stages of patient care, from evaluation and diagnosis through treatment and post-care. Pathologists, radiologists, medical oncologists, surgeons, radiation oncologists, nurses and social workers all work as a team to coordinate care and treat the whole patient. Together, they provide patients with carefully timed and monitored treatment, developed from multiple expert perspectives. Proton therapy will be an important part of this process.
Equally important is the value the center adds to MD Anderson's comprehensive translational research program, for which it has received more grants from the National Cancer Institute than any other medical institution in the U.S. And it has successfully transferred breakthrough knowledge from the laboratory to the clinic, extending the lives of thousands of patients.