RADIATION FIELD MODELING AND COMPUTERIZED TREATMENT PLANNING

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The vast improvements of the medical imaging and localization technology over recent years has brought a challenge to physics and computer technology to extend the capabilities of computerized treatment planning and optimization. A new photon beam model using a convolution kernel derived from experimental data has been derived and added as an alternative to the TPS for evaluation against the older NFD-based model. The number of integrated sectors in the electron beam model has been increased from 16 to 128, considerably improving the accuracy of irregular field dose distributions. A comprehensive set of tests has been devised to provide quality assurance of new versions of the TPS. The new version has the ability to permit working with a larger image (640 x 640) in addition to the standard images. A set of controls has been added to facilitate 3D, non-coplaner planning by interactively controlling gantry, collimator and pedestal. while instantaneously updating a 3D beam's eye view of the patient and all outlined structures. The ability to reflect the presence of tissue compensators in the dose distribution has been added. The handling of blocked photon fields using an experimental convolution kernel has also been added. The ability to move between multi-level images and dose distributions, as well as non-axial views (beams' eye, sagittal, coronal) using keyboard commands has greatly improved the clinical utility of the program. The next release, scheduled for the end of the year, will incorporate the ability to perform comparative treatment planning, will feature a standard 512 x 512 main window, with smaller secondary windows. The main image can be panned and zoomed for accurate outlining of small structures. The ability to add additional "drop" beam datasets will also be added. Coordinated CT-MRI planning will also be introduced using a set of tools to scale and register images and output the results in the standard TPS format. The final clinical version of the TPS is scheduled for June, 1997, and will incorporate an electron beam algorithm with inhomogeneity correction and the ability to perform brachytherapy calculations using the AAPM TG-43 formalism. The development of the TPS as a major research effort of ROB will also conclude, so that research can concentrate on other areas.