| 摘要 |
An optimization method for a fluence pattern to be provided via a radiotherapeutic apparatus comprising a multi-leaf collimator comprises an iteration of a progressive solution (such as a gradient approach) of the fluence profile, at least some iterations including a weighted penalty function which varies between solutions favored by the collimator design and solutions not so favored, later iterations including the penalty function at a greater weight. Thus, the penalty function represents locally preferred solutions derived from the constraints of the multi-leaf collimator (MLC). As the iteration progresses, the greater weight assigned to the penalty function drives the method towards a solution which is possible given the MLC constraints. However, the lesser weight attached in the early stages of the iteration allows the method to settle towards a genuinely preferred solution. Overall, therefore, the method migrates towards a theoretically ideal solution and then diverts to a nearby practically possible solution. In this way, a solution is obtained which can be put into practice but is close to a theoretically ideal solution, ie a solution that would be preferred in the absence of MLC constraints. It is preferred that the penalty function is calculated over a part of the fluence profile in the region of the then location of the iteration solution. The method can be embodied in a suitable computer program, which can be stored on a data carrier. An apparatus can comprising a storage means in which the program is located and a processing means for running the program. |
