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Advanced programming offer
new weapon against prostate cancer
SAN FRANCISCO -- Feb. 19, 2001 -- A merger
of advanced mathematics with cutting-edge computer technology
may give doctors a powerful new weapon in the battle against
prostate cancer.
Researchers have developed a computerized
expert system that would help radiation oncologists optimize
placement of radioactive "seeds" for prostate brachytherapy,
a non-surgical treatment that has been growing in popularity.
Beyond providing treatment more precisely tailored to each patient,
the system targets escalated doses of radiation at tumor pockets,
and accounts for changes that occur in the prostate volume during
treatment.
Dr. Eva K. Lee, assistant professor of industrial
and systems engineering at the Georgia Institute of Technology,
presented details of the advanced treatment planning system today
at the 167th annual meeting of the American Association for the
Advancement of Science (AAAS) in San Francisco.
She says the system can potentially improve
tumor control, reduce uncomfortable side effects and cut the
cost of the procedure by dramatically reducing the time required
to design radioactive seed treatment, allowing optimized plans
to be created and revised in minutes as the procedure proceeds.
"The system allows us to effectively
manipulate the large number of variables involved, something
that is far too complex for even the best human experts,"
says Lee, who is also an assistant professor of radiation oncology
at Emory University School of Medicine. "We can deliver
better precision and create the optimal plan for each patient.
This system should help cut the recurrence rate for prostate
cancer and reduce toxicity to healthy tissue."
Prostate brachytherapy involves implantation
of tiny radioactive seeds in the cancerous prostate. Continuous
radiation from the seeds kills the cancer cells, allowing patients
to avoid surgery that can produce such complications as incontinence
and impotence.
To successfully treat the cancer, however,
physicians must carefully design the radiation dose, balancing
the high radiation levels needed to eradicate the cancer against
the need to protect healthy nearby tissue. Further complicating
treatment is the blood fluid buildup that occurs as needles are
inserted to place the seeds. Resulting changes in prostate volume
can mean delivering too little radiation at the beginning of
treatment and too much as the swelling subsides.
"It is very complicated to produce a
successful implant," says Lee, who collaborated on the work
with Dr. Macro Zaider, professor and head of brachytherapy physics
at Memorial Sloan Kettering Cancer Center. "Proper coverage
of the entire prostate is very important, but it can be very
difficult to carry out the plan. The seeds cannot always be placed
in the location you want, so you must be able to compensate for
that. Our system allows real-time planning, and corrections can
be made as you proceed."
Ultrasound images of the patient's prostate
are used by the system to help determine optimal radioactive
seed placement based on such variables as prostate volume, location
of tumor pockets, radioactivity levels of the seeds, location
of the urethra (which passes through the prostate) and regions
of the organ that may be unreachable by placement needles. Mixed
integer programming and computational optimization techniques
are the core technological tools used.
The system incorporates dose-calculation engine,
a modeling automatic design of seed configuration for use in
the operating room, magnetic resonance spectroscopy imaging information
to target escalated doses to tumor regions into a computer program.
It also allows planning to account for changes in prostate volume,
and an ability to correct seed configuration intra-operatively
to account for seed displacement, needle distortion, or unforeseen
difficulties encountered during implantation.
"To the physician, this will be a black
box," Lee says. "They will not need to know what is
going on with the mathematics. All they will have to do is tell
the system what they want in the plan."
In most current treatments, seed placement
is determined manually based on a simulation of the patient's
prostate. Done days or weeks ahead of the operation, this "pre-plan"
takes hours to produce. By cutting the planning time to as little
as 15 minutes, the system should reduce costs and allow physicians
to spend more time with their patients, Lee says.
The system, funded by the National Science
Foundation, the Whitaker Foundation, and CPLEX, a division of
ILOG Inc. is ready for commercialization, but it will have to
receive FDA approval before being made available to treatment
centers. However, Lee has used real patient data to compare her
system against treatment plans designed by radiation oncologists.
Those results suggest the system will provide significant improvements
in treatment outcomes.
The system operates on a wide range of computing
platforms, including Windows NT personal computers.
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