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Tomotherapy

Advanced technology makes it possible to deliver radiation with unprecedented precision.

Ever since radiation proved to be a valuable weapon against cancer, doctors and researchers have been looking for ways to make radiation treatments safer and more effective. The critical issue has been finding a way to deliver enough radiation to destroy abnormal cells while minimizing damage to surrounding healthy tissue. In this search, tomotherapy has been a remarkable leap forward.


How tomotherapy works

Tomotherapy combines state-of-theart intensity modulated radiation therapy (IMRT) with the precision of computed tomography (CT) scanning technology. Radiation oncologists create detailed three-dimensional maps of the size and location of a tumor and use these images to plot the tumor’s exact contours, the surrounding organs, and sensitive tissue. Then they prescribe the dose of radiation the tumor should receive. Based on the prescription, the tomotherapy system programs the appropriate pattern for the treatment, calculating the precise position and intensity of the radiation beams.

Part of tomotherapy’s groundbreaking technology allows a single radiation beam to be divided into thousands of tiny, narrow beamlets that deliver radiation from all angles, in a pattern planned by doctors and coordinated by computers. As the shape or the location of the tumor changes over time, the angles and intensity of the beams are adjusted as well to improve the effectiveness of the treatment.

Treatment with tomotherapy

Tomotherapy is a quick and painless process, with daily treatments that usually take about 20 minutes. The machine is shaped like a large ring, with a bench — sometimes known as a couch — that slides through the ring’s opening. The radiation therapist positions you on the couch, usually on your back. Once treatment starts, you move slowly through the center of the ring while lying on the couch.

The first phase is an initial CT scan using the tomotherapy equipment, so that the doctor can check whether the tumor’s anatomy has changed and adjust the planned dosage and delivery accordingly. The therapist may also change your positioning on the couch as a result of this scan, and may also use special equipment to keep you from moving during treatment. Then the couch once again moves you through the machine, which delivers radiation in the prescribed pattern, typically over the course of five minutes.

Uses of tomotherapy

Tomotherapy can be used to treat many cancers, some of which would have been difficult or unsafe to treat with conventional radiation. Here are some of the ways it’s used:

Retreatment: When cancer recurs in a part of the body that has previously been treated with radiation, retreating the area can lead to scarring and ulceration. Because of tomotherapy’s precision, retreatment is now safer and more effective for people who have reached their maximum tolerance for conventional radiation. In these cases, the initial CT scan to map the recurrent cancer is particularly important, since it can sometimes be difficult to distinguish between active recurring cancer and scar tissue from previous treatment.

Total Metastases Irradiation (TMetI): When multiple metastases are present, tomotherapy can target visible tumors in multiple areas of the body with high doses of radiation, while limiting damage to healthy tissue. In this case, doctors typically use tomotherapy in coordination with chemotherapy, which helps treat smaller metastatic sites, called micrometastases, that may not be visible or treatable with targeted radiation.

Brain tumors: Tomotherapy allows doctors to treat metastatic brain tumors — cancer that has spread to the brain from other parts of the body — with a two-step process. First, they treat the whole brain with a moderately low dose of radiation — not strong enough to damage the brain, but enough to eliminate scattered cancer cells that cannot be seen on scans. Then, doctors use tomotherapy to treat all visible brain tumors with extra radiation, while avoiding damage to healthy brain cells.

Head and neck cancer: Tomotherapy makes it possible for doctors to treat the lymph nodes in the tongue, throat, and larynx while avoiding the salivary glands. Damage to the those glands can result in permanent dry mouth, a condition known as xerostomia.