Tomotherapy

As a TomoTherapy radiation therapeutic method is called, similar to a diagnostic CT scanners, the beams can be directed from all sides on the part of the patient to be irradiated at the. To this end, rotating the radiation source in a corresponding ring ( see illustration). As radiation source a small linear accelerator of 6 MeV energy is used.

Highest precision in the alignment of the radiation is achieved by before each treatment with low-dose radiation from the linear accelerator, a CT image series creates a is used with the TomoTherapy unit combined CT scanner to control the exact positioning of the tumor to be irradiated (so-called image -guided radiotherapy IGRT ).

The strip-shaped radiation field of the linear accelerator is split by a multileaf collimator of 64 separately controllable closures in 64 rectangular single fields. Same time, each rotation of the system is mathematically divided into 51 directions of irradiation with 7 ° difference. Thus, each individual therapy session from tens of thousands of individual fields ( so-called beamlets ) that are individually modulated ( in strength varied). Therefore particularly complicated, possible to the target volume adjusted dose distributions are possible, similar to the earlier intensity modulated radiotherapy IMRT. The TomoTherapy can easily handle concave target volumes and as many goals in the same session.

With the irradiation of the tumor patient is often associated side effects will be reduced.

The treatment method was first used clinically in 2003. It is based on developments at the University of Wisconsin (USA). The only producer is the U.S. firm Accuray Inc.. Worldwide, about 300 units are in operation, including 11 in Germany and 3 in Switzerland ( as of 2011).

Hauptanwendungsbebiete the tomotherapy are malignant neoplasms such as prostate cancer, lung cancer, breast cancer and head and neck cancers.