What is "tomotherapy"

Tomotherapy or helical tomotherapy (HT) is a type of radiation therapy in which the radiation is delivered slice-by-slice (hence the use of the Greek prefix tomo-, which means "slice"). HT is a form of computed tomography (CT) guided intensity modulated radiation therapy (IMRT). HT machines are purpose built for IMRT and differ from IMRT delivered by conventional medical linear accelerators (LINACs) in a number of ways. The main difference is that in HT a narrow intensity modulated pencil beam is delivered from a rotating gantry while the patient is simultaneously moved through the bore, compared to the much wider intensity modulated beam and static patient in conventional IMRT. HT units are therefore better able to target treatment sites throughout the body without a pause for the patient to be moved and set-up differently.