Tomotherapy.

In commercial use since 2003, TomoTherapy is the youngest generation of radiation therapy used to treat malignant tumours. The technology has been in development since 1990 when a research team at The University of Wisconsin, Madison first began experimenting with the technology that would eventually turn into TomoTherapy.

The biggest and most obvious change from traditional methods of radiation delivery was the first step the researchers took: they mounted the radiation-delivering equipment ("Hi-Art" system) onto a "ring gantry" which allowed the device 360 degree access to their patients. This enabled the doctors to quickly reposition the Hi-Art so as to direct the beams of radiation in short bursts from multiple angles. Because beams of radiation enter the body from several different angles for short amounts of time, there is less damage to surrounding tissue. With older methods, static rays are aimed at the same spot over and over. This makes lower-intensity beams necessary which are less effective and because of the repeated exposure there is more damage to healthy tissue - despite the lower levels of radiation.

TomoTherapy allows doctors to perform radiation therapy in the most accurate way possible. The ring structure enables the doctor to perform a computed tomography (CT) scan between treatments so as to make certain the exact location of the tumor is targeted. Because of the frequent CT scans, doctors are able to adjust equipment positioning to compensate for shifts in anatomical structures. It is also possible to put patients in the best position possible to access the area receiving treatment.

The TomoTherapy system looks (from a patient's point of view) very similar to a CT machine. The patient lies on a couch which moves in and out of the ring gantry while the Hi-Art equipment orbits the body and shoots out beams of radiation. The process usually takes about 10-20 minutes, but of course this depends on the patient.