November 1994
Media Contact: Karin Twilde
Phone: (410) 955-1287

The Johns Hopkins Oncology Center has installed a new state-of-the-art radiation therapy simulation device that allows physicians to more precisely plan and deliver radiation treatment for cancer patients.

The high-tech device, called AcQsim (pronounced accusim), manufactured by Picker International, Inc., of Cleveland, is one of only a few operating in the United States. It combines the latest technology of diagnostic CT scans and computer software to provide three-dimensional treatment planning.

The AcQsim takes standard CT scans and generates three-dimensional images and simulation views on a sophisticated computer system. A team of radiation oncologists, radiation therapists and physicists then uses these 3-D images to develop treatment plans for patient therapy.

"Treatment planning is probably the most crucial part of radiation therapy. It's where we decide what dose of radiation to deliver and where to direct the radiation beam. The goal is to maximize the dose to the cancer and have minimum damage to healthy tissue or organs," explains Michael Herman, Ph.D., acting chief of medical physics in the Oncology Center's radiation oncology division.

Moody Wharam, M.D., director of radiation oncology, says the AcQsim system provides the physician with more precise information on the location of disease and of critical normal structures than does traditional two-dimensional simulation. "On the computer screen, beam orientation can be adjusted as bones and other parts of the anatomy are displayed to determine the optimal radiation beam path," he says.

Currently used two-dimensional treatment simulation cannot show what happens to normal tissue and organs surrounding the tumor site and leaves operators concerned about dose levels to healthy tissue. It also requires patients to remain motionless, sometimes for hours, on a flat table beneath a machine that simulates, using benign light rays, the path of radiation beams generated by a linear accelerator during actual treatment.

"With the AcQsim, we scan patients and send them back to the comfort of their own homes while our treatment planning team targets the tumor by viewing the treatment path as if it were the radiation beam," says Herman. He expects the AcQsim ultimately to replace two-dimensional simulation.

The first simulations with the AcQsim at Hopkins were in September.

-- JHMI --
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