Abstract: A volumetric modulated arc therapy (VMAT) treatment plan may be optimized by obtaining a VMAT treatment plan and calculating a radiation dose matrix corresponding to each a plurality of beamlets, wherein each beamlet represents a change in field when an MLC leaf is moved a predetermined unit distance. The method includes defining an enhanced objective function (EOF) for achieving one or more clinical objectives and minimizing the EOF for proposed leaf positions iterating through each leaf of at least a subset of the leaves of the VMAT treatment plan (wherein the proposed leaf positions move each leaf into the field or out of the field by the predetermined unit distance and correspond to the addition or subtraction of the corresponding radiation dose matrix). The set of leaf positions of the VMAT treatment plan is updated according to the proposed leaf positions of the minimized EOF.

Abstract: Linear accelerator (“linac”) downtime invariably impacts delivery of patients' scheduled treatments. Transferring a patient's treatment to an available linac is a common practice. Transferring a VMAT plan from a linac equipped with a standard-definition MLC to one equipped with a higher definition MLC is practical and routine in clinics with multiple MLC-equipped linacs. However, the reverse transfer presents a challenge because the high-definition MLC aperture shapes must be adapted for delivery with the lower definition device. An efficient method to adapt VMAT plans originally designed for a high-definition MLC to a standard definition MLC is disclosed herein. The dosimetric results of the present adaptation method are presented for head-and-neck, brain, lung and prostate VMAT plans. The delivery of the adapted plans was verified using standard phantom measurements.

Abstract: Linear accelerator (“linac”) downtime invariably impacts delivery of patients' scheduled treatments. Transferring a patient's treatment to an available linac is a common practice. Transferring a VMAT plan from a linac equipped with a standard-definition MLC to one equipped with a higher definition MLC is practical and routine in clinics with multiple MLC-equipped linacs. However, the reverse transfer presents a challenge because the high-definition MLC aperture shapes must be adapted for delivery with the lower definition device. An efficient method to adapt VMAT plans originally designed for a high-definition MLC to a standard definition MLC is disclosed herein. The dosimetric results of the present adaptation method are presented for head-and-neck, brain, lung and prostate VMAT plans. The delivery of the adapted plans was verified using standard phantom measurements.