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 TomoTherapy Hi-Art System® delivers a very sophisticated form of intensity-modulated radiotherapy (IMRT), and combines treatment planning, CT image-guided patient positioning and treatment delivery into one integrated system.

The equipment used for TomoTherapy looks much like a computed tomography (CT) system: the patient lies on a couch 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, targeting tumors with optimal levels of radiation while minimizing the dose to healthy areas. The movements of the couch and the rotation of the gantry can be easily adapted.

The advantage of TomoTherapy is having a radiation treatment beam projected into the tumor continuously as it rotates rather than having a limited number of fixed beams, each providing only a fraction of the dose necessary to irradiate the tumor. With the TomoTherapy Hi-Art System®, physicians can adjust the size, shape and intensity of the radiation beam to target the radiation to the size, shape and location of the patient's tumor.

In addition, the new TomoTherapy Hi-Art System® integrates imaging with radiation treatment, which provides physicians with full three-dimensional information for accurate daily patient positioning. It's TomoImage® capabilities allow physicians to verify the position of the tumor before each treatment session, so adjustments can be made on the spot to make sure that radiation is delivered exactly where it should be. The doctors can also adapt the doses before each treatment session in function of the results of the previous sessions.

The UZ Brussel was one of the first clinics worldwide to introduce in 1995 IMRT in clinical practice and the first European center to implement sequential tomotherapy clinically. The latter was customised to work on a conventional linear accelerator and, based on its success, the idea of a dedicated helical tomotherapy machine became a reality.

With the clinical implementation of helical tomotherapy, the UZ Brussel confirms again its pioneering role in radiation therapy by introducing new and challenging technologies for the benefit of the patient, after the introduction of the Novalis® Body Shaped Beam Surgery™ (Brainlab, AG) for stereotactic (body) radiosurgery in 2000.

"Since the TomoTherapy system increases treatment accuracy, patients may benefit from reduced side effects and improved clinical results", concludes Professor Guy Storme. “The ability to do 3-D imaging immediately before each treatment to verify the location of a tumour also increases precision.”

NEW TREATMENT APPROACH

The Tomo® Process combines treatment planning, CT image-guided patient positioning and treatment delivery into one integrated system:

Treatment Planning

Before beginning TomoTherapy treatment, the physician uses three-dimensional images and special software to define the precise contours for each tumor. The physician also decides how much radiation the tumor should receive, as well as acceptable levels for surrounding structures. Then the TomoTherapy Hi-Art Planning station calculates the appropriate pattern, position and intensity of the radiation to be delivered.

CT Image-Guided Patient Positioning 

Precise patient positioning is crucial for effective radiation treatment. With the TomoTherapy Hi-Art System®, physicians can take a special CT scan, called a TomoImage®, 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 tumours, such as prostate cancers, can change shape or shift from day to day. With the TomoTherapy Hi-Art System®, physicians can make sure that the radiation is directed precisely from one session to the next. 

Radiation Delivery

TomoTherapy combines intensity modulated radiation therapy (IMRT) with a helical delivery pattern. Photon radiation is produced by a linear accelerator (or linac), which rotates multiple times around the patient. The linac moves in association with a device called a multileaf collimator, or MLC. The computer-controlled MLC has two sets of interlaced leaves that modulate radiation beam while the patient, located on the treatment couch, moves slowly through the center of the gantry ring.