Frederic DeBros adjusts the position of a patient about to receive proton-beam treatment at the Harvard Cyclotron Laboratory. Photo by Jon Chase.

It's an old machine with a strange history as both an atom smasher and a tumor buster. No other atom smasher has ever treated so many cancer patients over so long a period.

Known as a "cyclotron" and located at Harvard University, the machine produces beams of atomic particles energetic enough to break open an atom or destroy a tumor. On Saturday, June 5, physicists and physicians will gather at the Harvard Cyclotron Laboratory to celebrate 50 years of experiments on the fundamental nature of atomic forces and the treatment of more than 8,000 cancer patients.

"The information that was obtained here is still used to aid our overall understanding of atoms, and the medical techniques developed here are used all over the world for treatment of brain, eye, prostate, and other cancers," notes Richard Wilson, Mallinckrodt Professor of Physics at Harvard.

"Even as we speak," he said in an interview this week, "patients are being treated. Also, the National Aeronautics and Space Administration [NASA] still does an occasional experiment at the laboratory to learn about the effects of radiation in space."

The cyclotron takes protons from the hydrogen in water and whirls them around a circular track. Bursts of radio waves gradually increase the speed and energy of these positively charged particles until they form powerful beams. The invisible beams then collide with atoms, tumors, or payloads that must survive in outer space, where protons fly around freely.

Protons and neutrons make up the cores, or nuclei, of every atom. Given enough energy, beams of them can crack open any atom to reveal what's inside. Protons and neutrons also are slammed into each other to study the forces that bind them together inside an atomic nucleus.

Norman Ramsey participated in the construction of the cyclotron, then used it for experiments in basic atomic physics from 1949 until 1962.

The radioactive beams destroy tumors that cannot be reached effectively by surgery, drugs, or other types of radiation such as X- rays. "X-rays go through a tumor but protons can be made to stop inside it, allowing the particles to better concentrate radiation where you most want it," Wilson explains. "That delivers a higher dose to the tumor while a lesser dose reaches normal tissues nearby. As a result, higher cure rates are possible with no more, and often less, unwanted side-effects."

Drafted for War

The June 5 celebration is open to the public. It features tours of the cyclotron and a symposium that will discuss its history and the pioneering experiments done there.

Harvard built the first such machine in 1937, but the federal government drafted it during World War II. It was taken apart and shipped to Los Alamos, N.M., in 1943, for service in designing the first atomic bombs.

The move had to be made in secrecy, so a radiation therapist arrived at Harvard to request its movement for what he said were medical purposes. Percy Bridgeman, a University researcher who won a Nobel Prize in Physics in 1946, told the government agents they could not have the machine if they were going to use it for medical purposes. But, he added, "if you are going to use it for what I think you're going to use it for, you are welcome to it."

After the war, the government never gave back the cyclotron, so Harvard received funds from the Office of Naval Research to build a new one, completed in 1949. From then until 1967, physicists from many parts of the world used the machine to increase knowledge about the nature of atoms and their interactions with each other.

"We did good, basic measurements of atomic forces that are fundamental for understanding the nature of all matter," notes Norman Ramsey, Higgins Professor of Physics Emeritus and a Nobel laureate. He helped supervise construction of the machine and did experiments at the laboratory until 1962.

The facility trained about 30 doctoral students in atomic physics, who in turn spread their knowledge throughout industry and academia.

"One of them was Allan Cormack, who worked as a research associate with Dick Wilson and me," Ramsey recalls. "We knew he was doing other work on the side, but we didn't stop him. That work had to do with developing techniques to analyze CAT scans, and Cormack later won a Nobel Prize in Medicine for it. Since we never stopped him from doing what we thought of then as boondoggling, Dick and I and Harvard like to take some credit for the award."

Richard Wilson came to Harvard in 1955 and upgraded the energy of the proton beam emitted by the cyclotron. He then conducted many physics experiments, the results of which are still used by researchers today.

One of the designers of the cyclotron, Robert R. Wilson, thought of using the machine for medical purposes even before it was built. With the proper energy and positioning of the beam in relation to the patient, he concluded, protons would travel rapidly through healthy tissue and cause minimal damage. If they hit the tumor as they slowed down and stopped, the particles would cause a maximum of destruction in the malignancy.

"Those calculations were what made the Harvard cyclotron so successful for cancer treatments," Ramsey says. "Other cyclotrons tried to do the same, but never could do it as successfully as we did."

In 1961, Raymond Kjellberg, a young neurosurgeon at Massachusetts General Hospital in Boston, became the first to use the Harvard beam to treat a malignant brain tumor. By the time of his death in 1993, Kjellberg had treated nearly 3,000 patients.

Kjellberg, Wilson, and others tried to interest various medical institutions in proton-beam treatment for cancer, but to no avail. Physicians insisted, in the late 1960s, that cancers would be cured by chemotherapy.

"That view turned out to be drastically over- optimistic," Wilson says wryly.

Reaching A Low Point

The cyclotron facility reached its low point in 1967-68. Physicists began to use machines that produced much higher energy for research on subatomic particles, and proton treatment of tumors had not caught on yet. In 1968, Andreas Koehler, now assistant director, was the only employee, part-time. That year, the government classified the cyclotron as "excess property" and announced that anyone who was interested could have the machine and ancillary equipment for the cost of removal.

There were no takers, so Kjellberg continued to treat patients. By the mid-1970s, he and his colleagues developed methods to treat larger brain tumors. Koehler and his team worked out techniques for treating various eye tumors. These included choroidal melanomas that, before proton therapy, had been treated by removing the eye. These medical successes impressed the National Institutes of Health enough for it to provide funds that rescued the machine.

More recently, the cyclotron laboratory added treatments for certain forms of macular degeneration, the leading cause of blindness in older people. New collaborations were started with Massachusetts General Hospital and the Massachusetts Eye and Ear Infirmary in Boston, which continue to this day.

In the 1990s, under director Miles Wagner, the lab has been giving 25 treatments a day, five days a week. During the evenings and on weekends, NASA has been conducting experiments on radiation protection for satellites and on how light atoms in young stars combine to make heavier, more complex elements.

Cancer treatments will soon be taken over by the Northeast Proton Therapy Center at Massachusetts General Hospital. This regional center can accommodate up to a thousand patients a year, and researchers there will investigate new approaches to cancer therapy.

Those interested in the June 5 symposium can find a program and other details at http://phys4.harvard.edu/~wilson/50th_anniversary_of_cyclotron.ht ml.

The Cyclotron will be open to visitors from 8 a.m. to 5 p.m. on Saturday, June 5. It is located at the Harvard Cyclotron Laboratory, 44 Oxford St., Cambridge.

The symposium celebrating 50 years of science and medicine at the Cyclotron will be held June 5 at the Science Center, Kirkland and Oxford streets, Cambridge, from 8:30 a.m. to 5:45 p.m. END