Image Guided Radiation Therapy: Trilogy vs TomoTherapy
Jay J. Zheng, Ph.D., D.A.B.R.
21st Century Oncology, Inc.
Radiation Oncology
Centers of
Abstract: Image
Guided Radiation Therapy (IGRT) has been increasingly adopted by clinicians in
radiation oncology around the world. Leading the technology, TomoTherapy, Inc. and Varian Medical Systems, Inc. have
introduced their unique, yet different ways of doing IGRT. A TomoTherapy machine is capable of
generating approximately 3.5 MV computerized tomography (MVCT) of a patient at
pre-treatment position. Fusion of the MVCT images with the KVCT images
used in planning produces shifts for moving the patient to the desired position
for treatment. On the other hand, Trilogy utilizes its isocentrical
On-Board Imaging (OBI) device to create either a 2D match with a pair of
orthogonal KV images or a 3D image fusion with the