Method to optimally splitting arcs in modulated arc therapy (MAT) plans

A system for identifying possible are segments for removal in a modulated arc therapy plan, the system comprising:

• at least one electronic processor programmed to:
• iteratively optimize a modulated arc therapy plan for an initial arc segment;
• compute respective geometric freedom (GF) metrics for each control point (CP) of the initial arc segment, wherein an individual GF metric indicates whether a specified nominal dose of radiation can pass through target voxels associated with a corresponding CP without passing through an identified critical organ voxel;
• and
• determine contiguous groups of CPs with GF metric values below a pre-selected threshold as candidate arc segments for removal from the modulated arc therapy plan.

A method of identifying possible arc segments for removal in a modulated arc therapy plan, the method comprising:

• iteratively optimizing a modulated arc therapy plan for an initial arc segment;
• computing a geometric freedom (GF) metric for each control point (CP) of the initial arc segment by operations including:
• computing a ratio, for each beamlet of the CP, of a number of tumor voxels touched by a beamlet divided by a sum of a number of voxels of critical organs touched by the beamlet;
• summing the GF metric values for the beamlets of the CP to generate the GF metric for the CP;
• determining contiguous groups of CPs with GF metric values below a pre-selected threshold as candidate arc segments for removal from the modulated arc therapy plan;
• and
• estimating a re-distribution of a dose of the modulated arc therapy plan with the candidate arc segments removed from the modulated arc therapy plan.