What is TomoTherapy?

TomoTherapy is a new way to deliver radiation treatment for cancer. TomoTherapy literally means "slice therapy," and gets its name from tomography, or cross-sectional imaging. The revolutionary system delivers a very sophisticated form of intensity-modulated radiotherapy (IMRT), and combines treatment planning, patient positioning, and treatment delivery into one integrated system.

Unlike traditional radiation therapy systems, which deliver radiation through one or a few separate beams, TomoTherapy delivers radiation with a rotating, intensity-modulated fan beam. The patient lies on a bench that moves continuously through a rotating ring. As it revolves around, the ring delivers photon radiation in the shape of a fan beam. The result is that radiation is delivered in a spiral rotation around the patient, hitting tumors with high levels of radiation while keeping the dose from hitting healthy areas.

What is the advantage of TomoTherapy?

The advantage of TomoTherapy is having one radiation beam projected into the tumor from all different positions as it rotates, rather than having several beams, each with only a fraction of the dosage necessary to irradiate the tumor With TomoTherapy, we can adjust the size, shape, and intensity of the radiation beam and actually 'sculpt' the radiation to conform to the size, shape, and location of the patient's tumor.

In addition, the new TomoTherapy system integrates imaging with radiation treatment, which provides doctors with full three-dimensional information for accurate patient positioning. Its computerized tomography (CT) capabilities allows doctors to verify the position of the tumor before each treatment dose, so adjustments can be made on the spot and ensure that radiation is delivered only where it should be.

Researchers at the University of Wisconsin-Madison, who were exploring ways to deliver intensity modulated radiation therapy (IMRT), first developed the concept of helical TomoTherapy. TomoTherapy Inc. was later founded by two members of the research group: Professor Thomas "Rock" Mackie of the University of Wisconsin-Madison, Department of Medical Physics and Human Oncology, and Paul J. Reckwerdt, an accomplished mathematician and software engineer. The system received 501(k) clearance from the U.S. Food and Drug Administration in February 2002.

The John T. Vucurevich Cancer Care Institute was chosen as one of the first 10 research centers in the world to offer the revolutionary technology. The equipment used for TomoTherapy looks much like a computed tomography (CT) system: the patient lies on a table that moves continuously through a rotating ring gantry. The gantry houses a linear accelerator, which delivers radiation in the shape of a fan beam as the ring is turning. With the couch moving at the same time the gantry is rotating, the radiation beam makes a spiral (or helical) pattern around the patient.

Treatment Planning

Before beginning TomoTherapy treatment, the doctor uses three-dimensional images and special software to establish the precise contours for each tumor and any surrounding regions at risk, such as sensitive organs or structures. The doctor decides how much radiation the tumor should receive, as well as acceptable levels for surrounding structures. Then the TomoTherapy system calculates the appropriate pattern, position, and intensity of the radiation beam to be delivered.

Patient Positioning

Precise patient positioning is crucial for effective radiation treatment. With the TomoTherapy system, our doctors can take a special CT scan just before each treatment to verify the tumor's location and adjust the patient's position, if necessary. This is extremely useful since a patient's position may change slightly from session to session and certain types of tumors, such as prostate cancers, can change shape or shift from day to day. With TomoTherapy, doctors can ensure that the radiation is directed right where it should be from one session to the next.

Radiation Delivery

TomoTherapy combines intensity modulated radiation therapy (IMRT) with a spiral delivery pattern. Photon radiation is produced by a linear accelerator (or linac), which travels in multiple circles all the way around the patient. The linac moves in unison with a device called a multileaf collimator, or MLC. The computer-controlled MLC has two sets of interlaced leaves that move in and out very quickly to constantly modulate the radiation beam as it leaves the accelerator. Meanwhile, the couch is also moving, guiding the patient slowly through the center of the ring, so each time the linac comes around, it's directing the beam at a slightly different plane on the patient's body.

Throughout the procedure, the patient can relax within the large bore, which has an opening nearly three feet wide. The linac and all the other rotating components are completely enclosed in the so that nothing comes in contact with the patient or the therapist.

Rapid City Regional Hospital is one of the first nine facilities worldwide to receive the groundbreaking TomoTherapy technology, and the only community-based hospital. We are fortunate and grateful that such technology, normally available only at university-based and larger metropolitan hospitals, is now available locally.

View Map of Hospitals with TomoTherapy Technology (PDF)

Institute Insider - TomoTherapy (PDF)