Danny Z. Chen Shuang Luan Chao Wang Coupled Path Planning, Region Optimization, and Applications in Intensity-Modulated Radiation Therapy. 271-283 2008 ESA http://dx.doi.org/10.1007/978-3-540-87744-8_23 conf/esa/2008 db/conf/esa/esa2008.html#ChenLW08