Terry Wu, Ph.D., Lane
R. Rosen, M.D., Sanford Katz, M.D.
Intensity Modulated Radiotherapy (IMRT) and Imaged Guided
Radiotherapy (IGRT) has become a treatment of choice in many institutions. IMRT
provides a better dose distribution and conformality within and around a lesion,
while IGRT helps manage both inter- and intra- fraction positioning thereby
improving the accuracy of treatment delivery. Tomotherapy is a new radiation modality
that combines the use of sophisticated computer-controlled helical IMRT with an
on-board Megavoltage Computed Tomography (MVCT) scanner for image guidance (IG)
of the treatment area (IG-IMRT). It provides an unmatched accuracy in beam
delivery and patient positioning allowing for a potential increase in tumor
dose with decreased complications.
The entire Tomotherapy IG-IMRT process including patient immobilization, CT simulation, treatment planning, plan verification, patient setup, radiation delivery and QA will be reviewed. Several complex clinical examples utilizing Tomotherapy will be presented. These cases include examples of fractionated extracranial radiosurgery in the lung and esophagus, craniospinal irradiation and whole abdomen radiation therapy (WART). Preliminary results (40 patients) from fractionated lung radiosurgery for small lung tumors are promising. Treatment tolerance has been excellent with favorable measured lung volume parameters (V(20)). For craniospinal radiation, Tomotherapy offers significant advantages over the traditional matching field technique by eliminating the need for field junction and gap feathering while allowing supine positioning. Dosimetric homogeneity is also improved by minimizing the cold and hot spots. Treatment and planning with Tomotherapy is easily accomplished even with most complex cases. It will be demonstrated that Tomotherapy has the potential to significantly improve the delivery of radiation therapy in the future.