Patent ID: 8858414

Claim:
A programmable method for setting subarcs in a segmented short-arc volumetric modulated arc therapy (VMAT) to fit a breath-hold interval, comprising the following steps: (a) dividing an arc in the VMAT into a certain number of subarcs; (b) setting four cut-edge control points within each subarc to form three segments, each segment defining a range over which a prescribed dose of radiation is delivered with the segments arranged in a continuous manner on the subarc and the delivery of the prescribed radiation dose being continuous through the segments; (c) setting monitor units (MUs) for the segments within each subarc, wherein the monitor units for a starting (first) control point, second control point, third control point and stopping (fourth) control point are designated as MU 1 , MU 2 , MU 3 and MU 4 , respectively, and the stopping control point is a starting point of a subsequent subarc; and (d) determining a dose distribution within each subarc by setting delivered MUs in each segment, wherein the delivered MUs in a first segment are distributed according to a formula: MU 1 +X 2 MU 2 ; the delivered MUs in a second segment are distributed according to a formula: (1−X 2 ) MU 2 +X 3 MU 3 ; and the delivered MUs in a third segment are distributed according to a formula: (1−X 3 )MU 3 +X 4s MU 4 ; X 2 is a proportion of the delivered MUs distributed for the first segment between the starting control point and the second control point, while (1−X 2 ) is a proportion of the delivered MUs distributed for the second segment between the second control point and the third control point; X 3 is a proportion of the delivered MUs distributed for the second segment between the second control point and the third control point, while (1−X 3 ) is a proportion of the delivered MUs distributed for the third segment between the third control point and the fourth (stopping) control point; and X 4s is a proportion for converting the delivered MUs at the stopping control point to that at the starting control point of the subsequent subarc; wherein each subarc is in an interval less than a single breath-hold.