Global optimization of treatment planning for external beam radiation therapy.
External beam radiation therapy is a well-known option for treating and controlling certain central nervous systems lesions, such as arteriovenous malformations, metastatic lesions, malignant gliomas, and tumors in various parts of the body. The process of treating a patient using external beam radiation therapy consists of constructing a precise three-dimensional map of the anatomical structures in the location of interest (target volume), developing a treatment plan for delivering a predefined dose distribution to the target volume and executing the plan using an accepted beam delivery apparatus. Thus, the basic strategy of external beam radiation therapy is to utilize multiple beams of radiation from multiple directions to "cross-fire" at the target volume so that radiation exposure to normal tissue is kept at relatively low levels, while the dose to the tumor cells is escalated.
Current methods for treatment planning include a manual trial-and-error approach and computer aided models that incorporate fixed variables. None of the current approaches can optimize a treatment plan easily for a physician.
The present invention improves existing methods by describing a system for providing a globally optimal treatment plan for delivering a prescribed radiation dose to a target tumor volume within a patient using an external beam radiation source. In the field of external beam radiation therapy, the present invention reduces normal tissue complications, improves tumor control, enables physicians to evaluate a set of globally optimal solutions, reduces the time and cost associated with producing a treatment plan, eliminates trial and error visual optimization, enables physicians to perform radiation therapy in complex situations, such as where critical structures are near the tumor, improves the percentage of tumor volume covered by a prescription isodose line, reduces the ratio of the maximum dose to the prescribed dose, improves the ratio of the volume of the prescribed isodose surface to the target volume, and improves the ratio of the maximum dose received by normal tissue to the prescribed dose.