Nearly two thirds of people diagnosed with cancer today will receive radiation as part of their therapy. Incremental improvements in technology over the last century have culminated in what Chair of Radiation Oncology Walter J. Curran Jr., M.D. calls "revolutionary improvements over the last decade." At Jefferson's Kimmel Cancer Center, that revolution can be seen at the 50,000 square foot Bodine Center for Cancer Treatment, opened 12 years ago not only to offer the best, but also to ensure the continual development of new radiation therapy technologies.

What has changed in recent years, said Curran, is that radiation oncologists and other cancer specialists have learned that the best cancer treatment often incorporates multiple specialties and modalities. "With trained oncology nurses, with pharmacists, with psychologists and social workers, the Bodine Center was one of the first centers in the Philadelphia area to recognize the need for multispecialty collaboration in the management of cancer patients," said Curran. "And we still serve as a model of that." Radiotherapy may be used in conjunction with surgery or chemotherapy to achieve more complete tumor elimination or to control metastasis, and in some cases it can also be used in place of surgery when the goal is to preserve organ function, such as in the case of cancers of the throat, larynx, esophagus, prostate, and breast.

And even when a cure is not the goal, palliative radiotherapy may provide significant benefit to patients with cancers that are locally advanced or that have spread to the bone or the brain. Said Curran, "Probably about half of patients who have incurable cancer benefit from radiotherapy in terms of quality of life and pain control."

The approach that Jefferson uses incorporates different technologies to provide image-based treatment planning and delivery. That typically includes techniques that immobilize the patient to the greatest degree possible; imaging modalities such as spiral CT scanning, which provides high resolution images; and planning tools that calculate the most effective way to deliver the right dose of ionizing radiation to the target while sparing normal tissues.


Precision Targeting

For the more than 200,000 men each year diagnosed with prostate cancer, all of the treatment options have risks. Surgery, while offering the potential of complete removal of the tumor, too often results in damage to the surrounding nerves, sometimes resulting in impotence and incontinence. Radiotherapy, in contrast, offers an increased likelihood of retaining sexual potency. Yet irradiating prostate tumors buried deep in the pelvis places nearby sensitive structures such as the rectum and bladder at risk of radiation-induced damage. In order for radiation therapy to be an acceptable alternative in prostate cancer and many other forms of cancer, techniques have been developed that concentrate the delivery of ionizing radiation to the tumor itself, while limiting radiation exposure of the surrounding tissue.

The traditional approach to treatment planning, called conformal 3-D treatment, is to look at the cross-sectional CT image of the tumor and arrange the fields to miss healthy structures as much as possible, and then to irradiate the tumor from a number of different directions. "That works rather well in concentrating the radiation in the target area and sparing the critical structures," said James M. Galvin, D.Sc., Professor and Director of the Medical Physics Division in the Department of Radiation Oncology. "We use our bag of tricks to get a good dose distribution." These tricks include various techniques that weight the fields differently and modify them with absorbers placed in the beam.

An alternative to the traditional approach to treatment planning, called inverse planning, is now being used at Jefferson. Employing a delivery system called "Peacock" which was developed by Nomos Corporation of Sewickley, Pennsylvania, it allows the radiation oncologist to start with what is the ideal dose distribution and to work backward from that point to determine the appropriate configuration of radiation delivery. "It's a total reversal of the approach," said Curran. "Normally we think of the fields and base the dose strictly on that. Here we think of the dose and then use the treatment planning technology to determine the delivery process that will give us that dose."

The Peacock system delivers what is called intensity modulated radiation therapy (IMRT), using an approach known as "layered therapy," said Maria WernerWasik, M.D., Assistant Professor of Radiation Oncology. A special crane moves across the treatment table, delivering many small radiation beams of varying intensity. This allows the physician to modify the delivery of radiation to conform to the shape of the tumor, even if it is an irregular shape, and to get uniform levels of radiation to tumors that vary in thickness and that have hard-to-reach margins, while at the same time avoiding normal tissue. "It's the radiation oncologist's dream to be able to do this," said Werner-Wasik. By delivering radiation more precisely, Peacock allows the physician to deliver higher levels of radiation without harming normal tissue, thus increasing the likelihood of cure.

In addition, physicians may be able to provide a second course of radiotherapy when necessary. "Peacock may allow us in some cases to treat tumors that recur after initial courses of radiation," said Werner-Wasik.

The key to inverse planning is computation, according to Calvin. "You give the computer very detailed geometric information about the tumor you're trying to treat, and also about the critical body structures in the vicinity," he said. "Then you ask the computer to determine the ideal combination of beams and angles that will deliver a homogeneous dose of radiation to the various areas of the tumor regardless of its shape. And you give the computer the flexibility of varying the beam intensity at will."

The idea of inverse planning was developed in the 1980s and '90s, before there were convenient ways available for modulating the beam intensity point for point. "It was a technique in search of a technology to 

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