An automated approach to seed assignment for eye plaque brachytherapy

Episcleral plaques are commonly used for the treatment of ocular rumours su ch as choroidal melanoma. Treatment planning involves the assignment of see ds to slots on the plaque to achieve a desired dose rate distribution. Seed assignment is rather straightforward if seeds are ordered on demand. Howev er, the assignment task becomes tedious and laborious if the seeds have to be chosen from an existing stock of seeds with different activities. To dar e, this task has usually been performed by a human planner through trial an d error. An algorithm has been developed to automate the task of seed assig nment using a mixed-integer programming method. We also explore ways to sim plify the problem such that the method becomes practical in most facilities . We have tested the method on three randomly chosen clinical cases from ou r past records, to show that the algorithm could yield solutions within a s horter time frame and with less deviation from the desired dose rate distri butions, as compared with the solutions from a human counterpart.