Multi-Source E-Beam kV X-Ray Tube for Image-Guided Radiotherapy

DESCRIPTION provided by applicant This project will lead to the development of an optimized X ray tube with focal spots that can be placed immediately below and around the multi leaf collimator MLC of a radiotherapy system By steering a focused electron beam e beam on a series of cooled tungsten targets in sequence this system will provide a set of projection images that can be reconstructed into a cm cm cm digital tomosynthesis DTS volume image that surrounds the radiation target The projection X rays are captured by a universal kV MV imager that can record portal MV images interlaced with the sequence of tomographic kV images Since the sources are positioned around the perimeter of the MLC the resulting tomographic cross section images are aligned perpendicular to the axis of the therapy beam This geometry is referred to as andquot Beamandapos s Eye Viewandquot imaging The DTS images will be used to provide precise reference coordinates of a tumor surface for programming of the MLC in near real time The preliminary specifications for the system indicate that a repetition rate of volume image per second with near mm spatial resolution will be possible The multi source e beam X ray tube will be developed by substantially the same premier team who developed the original Imatron EBCT scanners and the more recent e beam luggage scanner The e beam team consisting of TeleSecurity Sciences Inc scientists consultants and vendors has partnered with the premier cone beam CT team at UC Davis along with a key Varian consultant who are authorities on flat panel X ray imagers and in particular the kV MV imager that will be used in this project to provide simultaneous MV portal imaging with interlaced kV DTS imaging of the tumor position Phase of the project will extend the preliminary work to more precisely define the final design specifications for a future commercial system that will be appropriate for the entire radiotherapy industry Phase funding will develop a suitable prototype of the multi source e beam X ray tube which will demonstrate the feasibility and performance of the commercial system The majority of radiotherapy vendors have provided guidance and letters of support for this project The commercial implementation of the proposed system in future radiotherapy systems will permit treatment plans that will have far improved localization of radiation exposure within reduced margins beyond the apparent boundaries of a malignant mass with a corresponding reduction in exposure to surrounding normal structures This will be especially important in treating tumors of the chest and upper abdomen during free breathing where periodic motion in the range of cm to cm is often encountered

PUBLIC HEALTH RELEVANCE We propose a novel andquot Beamandapos s Eye Viewandquot BEV digital tomosynthesis DTS imaging system for image guided radiotherapy consisting of a kV multi source electron beam e beam X ray tube and universal kV MV imager which will generate higher contrast images in real time enabling better treatment local control for more patients with less collateral damage The multi source e beam X ray tube will be integrated into the radiotherapy gantry and provide projection images needed for the BEV DTS imaging in less than second The BEV DTS images reconstructed from the projection images recorded by the universal kV MV imager will be of high contrast resolution and be used to provide accurate tumor tracking information to the multi leaf collimator in real time with Hz update rate