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Wednesday, April 05, 2006



Radiation kills cancer cells, but the treatment also can affect surrounding healthy tissue.

Two hospitals in mid-Michigan have added new external radiation technology that works with computerized images to better protect healthy cells and pinpoint tumors throughout treatment.

St. Mary's of Michigan's Seton Cancer Institute in Saginaw is using the TomoTherapy HI-ART System. TomoTherapy has a rotating radiation beam that is constantly modulated to target the exact shape of the cancer.

Before each treatment, a clinician takes a verification CT (computerized tomography) image to make sure the beam is targeted directly on the tumor. Some types can change shape or even shift from day to day, with patient weight loss or shrinking of the tumor.

Doctors initially map the tumor with computerized imaging. The verification scan is compared to the original image to guide the radiation.

During treatment, radiation rotates 360 degrees as the patient lays on a bed that moves through the machine. TomoTherapy delivers small beamlets of high-energy radiation from every point on a spiral, which allows for treatment of large tumors and multiple sites at the same time.

The machine, made by TomoTherapy Inc. of Madison, Wis., cost $3.5 million. There are 56 in use in the world, including four in Michigan -- which has the most of any state, company representatives said. The others are in Flint, Lansing and Grand Rapids.

In Midland, MidMichigan Medical Center has an updated version of a linear accelerator radiation machine called the Varian Clinac IX with on-board imaging and image-guided capabilities. MidMichigan invested $3.3 million to install the equipment, which is in use in 50 hospitals in the country.

The Clinac IX can use several types of imaging, including X-ray and CT scan, to verify the position of a tumor right before treatment. When healthy tissue is protected, it sometimes allows doctors to administer stronger doses of radiation to destroy the tumor, said Dr. Rajnikant H. Mehta, radiation oncologist at MidMichigan.

This machine in Midland also tracks internal movement during treatment and can block radiation as the tumor moves out of position during the patient's breathing cycle. This is especially important for lung cancer patients, Mehta said.

Radiation is used to treat cancer because it destroys the ability of cells to grow and multiply. Healthy cells around the treatment site will recover and resume normal activity, but radiation can cause side effects -- both long and short term.

With older technologies, doctors have to plan larger margins surrounding a tumor to make sure radiation will hit all the cancerous tissue. These newer systems that better track tumor size and location allow for smaller margins and less surrounding damage, doctors said.

For David J. Kabat, 68, of Saginaw Township these advances will help him get through eight weeks of radiation therapy to treat his prostate cancer. Last week, Kabat was the first patient to undergo TomoTherapy treatment at St. Mary's.

"I was a little hesitant at first, but it was a piece of cake," Kabat said. "I had seen something on TV about this therapy, but I had no idea it was in Saginaw. My doctor said this was the place to be and the way to go."

The prostate is one of the male sex glands, about the size of a walnut and located just below the bladder and in front of the rectum.

In treating prostate cancer, initial radiation side effects can include skin irritation, abdominal discomfort such as gas or cramping, frequent urination and fatigue.

Scarring also can appear over time, and in some patients, cause narrowing of the inside of the bowel. Scarring of nerves in the prostate area can cause erectile dysfunction.

In his early treatment, Kabat said he experienced no problems. He will continue the procedure five days a week. Each visit may take about 30 minutes, but the actual radiation time lasts just a few moments.

"I'm not worried about the cancer now," said the retired paper plant supervisor and father of four.

TomoTherapy is "beyond state of the art," said Dr. Michael C. Cappelli, radiation oncologist at Seton.

The Institute also has two linear accelerator machines for external radiation, which it will continue to use on patients who face less risk of side effects.

"Use of the TomoTherapy will be based on the tumor location and its proximity to critical structures," Cappelli said. "We can reduce the surrounding margin by four times."

With the rotating radiation, there are "no limits" to treatment, he said. The radiation can deliver to sites from head to toe without other body structures getting in the way, he added. The machine opens and closes as it spins to put radiation only on the target site. Patients won't have to move into different positions, Cappelli said.

Clinicians won't have to immobilize patients as completely, and in treating brain tumors, they won't have to use metal frames that screw to the skull.

The machine also can perform "radiosurgery" on the head or body, which involves a one-time high dose of radiation. Doctors also could retreat a location after a previous full course of radiation, Cappelli said.

MidMichigan began using its new Clinac machine in late December, and is building up to taking more advantage of its imaging capabilities, said Courtney Szelesi, manager of the radiation/oncology department.

This fall, Saginaw Radiation Oncology Center, 4141 Tittabawassee, will add pieces to its Varian Clinac 21 EX linear accelerator to provide image-guided radiation therapy. The Center is a joint service of Covenant HealthCare of Saginaw, Bay Medical Center of Bay City and MidMichigan Medical Center of Midland. v

Jill Armentrout is a features writer and Neighbors coordinator at The Saginaw News. You may reach her at 776-9681.

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