The development of GAMMA knife treatment planning system

GAMMA-TPS was a three dimensional treatment planning system of high performance specially developed for ELEKTA's GAMMA Knife Treatment System, which had an independent image input system of Microsoft Windows' style based on personal computer (486 or higher) and multimedia card and a main planning system of X-Windows' style based on SGI INDIGO2 workstation. It worked with a nice and friendly graphical interface; could input and manage patient's details; extract external contours automatically and determine contours of target or ROIs interactively; reconsf interest within skull, at the same time of contour-drawing; determine automatically or interactively the parameters of focuses, such as number, position, collimator size, source distribution etc; make dose prescription at the point of maximum dose or at any other reference point and make out automatically the precise treatment time for each focus. To make GAMMA-TPS safer or for the sake of evaluation and scientific research, it provided the user with kinds of verification tools, such as volumetric dose distribution, Beam's Eye View, Dose-Volume Histograms, isodose contours, isodose surfaces, dose summary table, magnifier etc. As a result, it exported the treatment plan by means of laser jet printer. We presented the essential concepts of our treatment planning approach, and illustrated these in a clinical case.