COLLISION DETECTION AND AVOIDANCE DURING TREATMENT PLANNING

Purpose: To develop computer software that assists the planner avoid p otential gantry collisions with the patient or patient support assembl y during the treatment planning process. Methods and Materials: The ap proach uses a simulation of the therapy room with a scale model of the treatment machine. Because the dimensions of the machine and patient are known, one can calculate a priori whether any desired therapy fiel d is possible or will result in a collision, To assist the planner, we have developed a graphical interface enabling the accurate visualizat ion of each treatment field configuration within a ''room's eye view'' treatment planning window, This enables the planner to be aware of, a nd alleviate any potential collision hazards. To circumvent blind spot s in the graphic representation, an analytical software module precomp utes whether each update of the gantry or turntable position is safe. Results: If a collision is detected, the module alerts the planner and suggests collision evasive actions such as either an extended distanc e treatment or the gantry angle of closest approach. Conclusions: The model enables the planner to experiment with unconventional noncoplana r treatment fields, and immediately test their feasibility.