U. W. Medicine

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With mobility, a comeback:
intraoperative radiotherapy

IORT device

Using radiation intraoperatively to get negative margins after a tumor is resected came into vogue in the 1980s and 90s. The idea’s merit hasn’t waned, but the associated logistical hurdles – wheeling the anesthetized, monitored patient from the OR to a radiation vault and back again, through hallways and elevators – fell so far outside of heightened patient-safety standards that the practice was suspended.

Now IORT (intraoperative radiotherapy), like so many other technologies, is available via mobile device. With IORT traveling to the patient, instead of vice-versa, UW Medicine oncologists are again employing it.

“There’s only 10-15 of this device model around the country,” radiation oncologist Edward Kim said of the IORT instrument at UW Medical Center. “It’s designed specifically, shielded, to deliver radiation in a standard operating room.”

IORT cylinderIORT’s main advantages are its application of a relatively high single dose of energy and its ability to better exclude normal tissues from the beam’s path. It is appropriate for tumors of the pelvis, breast, head, neck and extremities, for gynecologic malignancies and, less frequently, for pancreas cancers.

“This technology can be very useful for tumors which emerge in the pelvis, a confined space where it’s very difficult to get wide margins,” surgeon Gary Mann said. “I work mostly with abdominal sarcomas and retroperitoneal sarcomas. They are often large, between 10 and 20 centimeters and touching or very close to major vessels, the liver and pancreas. Sometimes we will peel the tumor away from these critical structures … and radiate the most concerning margins in the hopes that we are extending the margin that we are unable to get surgically.”

Studies from Europe show that delivering just one dose of IORT with the newest mechanisms can produce results equivalent to the standard six-week pre- or post-op course of radiotherapy, Kim said.

Mann and Kim recently collaborated on IORT procedures that went so smoothly that the former process seemed as outmoded as black-and-white TV. Simplified, the new approach goes like this:

Gary Mann and Edward KimOnce the tumor is removed to its fullest extent, a cone-shaped apparatus through which the beam will travel is situated above the patient. At the cone’s bottom, a bevel is placed to shape and angle the beam. The 3,000-pound IORT device, which can pivot in multiple planes, is wheeled over and mated to the top of the cone. The team steps out of the OR as radiotherapy is delivered in a few moments, then the surgeon completes the operation.

“While the patient is open and the retractors are in, we examine the field together and look at the resected tumor. We discuss margins and areas of difficulty, and choose one or two that we think will benefit from IORT. We choose the appropriate cone size and bevel at the bottom to shape it to the field we want to radiate,” Mann said.

The relative ease of IORT’s mobile delivery nonetheless requires orchestration among the surgeon, radiation oncologist and physicists.

“Sometimes we plan for IORT and don’t deliver it, say, if the closest margin is on the back side, and intraoperative radiation can only come from the front.”

IORT’s recommissioning restores a valuable therapeutic option for cancer patients from throughout the Pacific Northwest. UW Medical Center is the sole facility west of Denver and north of San Francisco to employ this instrument.

To refer a patient or learn more, contact Dr. Edward Kim at 206.598.4100  or edykim@uw.edu.

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