News Media Home | Hopkins Medicine Home
November 1994
Media Contact: Karin Twilde
Phone: (410) 955-1287
E-mail:
ktwilde@welchlink.welch.jhu.edu
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.