Adaptive Radiation Therapy Real-time Planning Helps Physicians Target Changing Cancers
adiation therapy depends on careful planning. Physicians use advanced imaging and sophisticated calculations to develop treatment plans that precisely target tumors. But what happens when the target area changes during treatment? The Radiation Oncology team at Froedtert & The Medical College of Wisconsin is leading national efforts to find a solution.
“Tumors can shrink significantly during treatment,” said Christopher Schultz, MD, Medical College of Wisconsin radiation oncologist. “After a few weeks, a tumor may not be the size and shape it was at the start. Nearby lymph nodes may also shrink and patients may lose weight.” These changes can cause healthy tissues to move into the target field. For example, radiation intended to treat a tongue cancer may now threaten major salivary glands or the voice box. “The risk is that normal tissues will also get a high dose of radiation intended for the tumor,” Dr. Schultz said.
Recreating a treatment plan from scratch can take days. The alternative is adaptive radiation therapy (ART) – the use of daily computed tomography (CT) imaging and innovative software to make fast, precise adjustments.
“ART is ‘real-time’ treatment planning that lets us adapt dose coverage to the characteristics of the tumor weekly or even daily,” Dr. Schultz said. “Avoiding critical structures ultimately leads to fewer long-term side effects.”
For example, ART can be important for patients with prostate cancer. “The shape of the prostate may change daily based on the amount of pressure from the rectum and bladder,” said Colleen Lawton, MD, Medical College of Wisconsin radiation oncologist. “If the difference from the original scan is small, we reposition the patient. Without ART, if the difference is big, treatment would have to be rescheduled to allow creation of a new plan.”
ART ensures optimal treatment is delivered, which is better for the patient. Allen Li, PhD, Medical College of Wisconsin medical physicist, helped develop several tools that shave hours off the planning process. “In the case of prostate cancer, we can generate an adaptive plan in 10 minutes – while the patient is on the table,” Dr. Li said.
Only a handful of cancer centers worldwide offer adaptive radiation therapy to patients. Medical College of Wisconsin radiation oncologists and medical physicists have published extensively on ART, and frequently present their findings at national and international cancer conferences.
Biologically Based Adaptive Radiation
Adaptive radiation planning relies on anatomical information supplied by CT scans. “In the future, we will incorporate metabolic and physiologic information from PET (positron emission tomography) scans or advanced MRI,” Dr. Schultz said. “This information will let us see which part of a tumor is dying – and adjust treatment to give a higher dose to resistant areas, leading to individualized therapy. Ultimately, we’ll be able to provide better outcomes for patients.”
Christopher Schultz, MD Allen Li, PhD
Colleen Lawton, MD
Honored Among the Best
Thousands of physicians in the nation are surveyed annually to identify the most skilled specialists treating complex medical conditions. Overall, the list includes more physicians from The Medical College of Wisconsin than any other group, practice or institution in Wisconsin. A total of 270 Medical College of Wisconsin physicians who practice at Froedtert were nominated by peers as Best Doctors in America®
. Special Report 2012 866-680-0505 5
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