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Algorithms for Intenstiy-Modulated Radiation Therapy in 3D and 4D

October 12, 2004

Date: Tuesday October 12, 2004
Time: 11am-12:15pm
Location: Woodward 149

Shuang (Sean) Luan <sluan@cs.unm.edu>

Abstract: Intensity-modulated radiation therapy (IMRT) is a modern cancer treatment technique and aims to deliver a highly conformal dose to a target tumor while sparing the surrounding sensitive structures. A key to performing IMRT is the accurate and efficient delivery of discrete dose distributions using the linear accelerator and the multileaf collimator. The MLC segmentation problems arise in such scenarios, whose goal is to compute a treatment plan that delivers the given dose distributions in the minimum amount of time. In this talk, I will first present some new MLC segmentation algorithms and software. Our new algorithms, based on a novel unified approach and geometric optimization techniques, are very efficient and guarantee the optimal quality of the output treatment plans. Comparisons between our software with commercial planning systems and the current most well known leaf sequencing algorithm in medical literature showed substantial improvement. The treatment plan computed by our software not only takes much less delivery times (up to 75% less) but also has much better treatment quality. Our software has already been used for treating cancer patients at a couple of medical centers. During the course of radiotherapy, the patient anatomy and position tend to vary from that have been used for treatment planning. This gives rise to a possibility of insufficient dose coverage to tumors and overdose to the surround sensitive structures, which may eventually lead to treatment failures. So, in the second part of this talk, I will discuss some of the future directions of our research, especially in the area of 4-D IMRT, in which the organ and tumor motions are considered in the treatment planning.