Tomotherapy is a form of Intensity Modulated Radiation Therapy. In Tomotherapy a small beamlet rotates helically around the patient while choosing where in its rotation it will deliver dose. Like IMRT this allows highly conformal treatments, thus greatly reducing doses to normal tissue and reducing patient toxicity and complications. An advantage over standard IMRT treatments is that standard IMRT minimizes the dose to normal tissue by distributing it over a set number of field angles while Tomotherapy can distribute the same dose over all 360º. This also means that Tomotherapy treatments can be very quick and easy or the patient.

Tomotherapy machines also have unique geometry and mechanics which make it ideal for patient imaging. The cylindrical geometry is very similar to a CT imaging machine and performs its imaging in a very similar way. This benefits the patient by allowing 3-D pre-treatment imaging. These images improve setup by matching the images used for treatment planning to patient anatomy on the day of treatment thereby making sure that dose is delivered accurately to the target sites.