ABSTRACT
In radiotherapy high-energy beams such as photons, electrons, protons, neutrons, heavy ions, etc are used as a means to treat cancer. The objective of radiotherapy is to provide tumor control while compromising as little as possible the life quality of the patient. Tomotherapy is a unique therapeutic modality that includes intensity-modulated delivery in conjunction with tomographic verification capabilities. The group of tomotherapy processes just described provides a closed loop for planning, delivery and verification in radiotherapy. In tomotherapy such accuracy can be achieved in different ways. By using the computed tomography capabilities of helical tomotherapy, it is possible to develop a technique to obtain the six-parameter patient offset from the registration sonogram. Delivery modification is a valuable tool to account for patient offset previous to the treatment and may be a very useful tool to account for movements during treatment.
