Precise radiation therapy spares healthy tissue

Radiation therapy is a powerful and highly effective cancer treatment - it can kill malignant cells, dramatically shrink life-threatening tumors and reduce pain caused by cancer. But all that power can come with a price: Radiation can damage healthy tissue as well as diseased tissue.

When doctors use radiation to treat cancer patients, it's a delicate balance: damage or kill as many cancer cells as possible while limiting the potential harm to normal cells. One way to improve the response rates and tip the balance in the patient's favor is through advanced technology that can precisely target tumors.

Precision treatment

One relatively new treatment method, known as intensity-modulated radiation therapy (IMRT), uses some of the latest equipment and medical expertise to go after cancer. This expertise has been available at the Gibson Cancer Center since April 2005 under the direction of Dr. Thomas Walden, a radiation oncologist.

IMRT equipment includes a computer-controlled linear accelerator, a machine which produces high energy X-rays. It stands about 10 feet high and 15 feet long. It generates tightly focused photon beams or X-rays that can be specially molded to conform to the shape of a tumor - or even target specific points inside a tumor.

The equipment can be rotated around the patient so that the beams are delivered from the best angles. The beams also are adjustable, allowing higher doses of radiation to be delivered to the tumor and less harmful doses reaching nearby healthy tissue than with more conventional radiation treatment.

Planning is key

The treatment is carefully planned ahead of time by a team of experts, led by Walden and his associates. Three-D computerized tomography, or CT, images are made of the tumor and surrounding tissues. Other high-end scans, such as PET (positron emission tomography) and MRI (magnetic resonance imaging), may also be used to determine the exact location and shape of the tumor.

With this information, specialists can determine the radiation dose and energy beam configurations that will be needed. The team at Gibson Cancer Center includes chief radiation therapist Shari Nichols and radiation therapists Angie Horton, Regg McIntyre and Jacque White. In addition, physicist Saad Bennouna is directly involved in the treatment planning and overseeing the quality control program.

Because IMRT is so precise, it is particularly important for the patient to remain still. Often, special reusable devices - made of foam, plastic or plaster - are molded to help the patient maintain the proper position. These devices are used only for that specific patient. The patient's skin may also be marked to help accurately align the equipment. The alignment uses fixed laser light from wall mounts, visual positioning and radiographic confirmation (X-ray pictures).

Painless procedure

Even though the equipment may sound futuristic - perhaps a little scary - IMRT is painless. And while side effects are the same as with conventional radiation therapy, they occur less often and with less intensity, offering a better quality of life for the patient.

“For the patient with prostate cancer this means less irritation to the bowel and bladder near the prostate,” Walden said. “And for the patient with a head and neck cancer, less irritation of the parotid or salivary glands, resulting in reduced long-term incidence of dry mouth and impaired quality of taste.”

Compared with conventional radiation treatment, fewer IMRT treatments may be needed. But since each treatment is more complex, individual sessions may last a little longer. Patients usually are scheduled for IMRT treatments five days a week for six to eight weeks. Sessions typically last between 15 and 30 minutes.

“Most prostate cancer patients are able to maintain normal work and social schedules during treatment with the exception of the short daily break for treatment,” Walden said. “The whole cancer center staff works hard to ensure safe, accurate treatment as well as helping the patient to maintain quality of life. Our dedicated staff includes highly trained and caring nurses, nursing assistants, a social worker and a dietitian.”

IMRT is currently being used at the Gibson Cancer Center to treat breast cancer, head and neck cancers and prostate cancer. While about half of all cancer patients receive some kind of radiation therapy, IMRT is not appropriate or necessary for all tumors.

Amanda Crabtree is the public relations officer for Southeastern Regional Medical Center. You may reach her at crabtr01@srmc.org.

By Amanda Crabtree - SRMC News
Via: www.robesonian.com