Spot positioning based on minimum monitor unit (MU) constraint and optimization objectives for a radiation therapy system

A computer system comprising a processor coupled to a bus and memory coupled to said bus wherein said memory is programmed with instructions that when executed cause said computer system to implement a method of determining spot positioning for each field associated with a target volume (TV), said method comprising:

• accessing dose volume constraints and information associated with a TV structure and an associated organ at risk (OAR) structure;
• determining a respective density map for each of the TV structure and the OAR structure;
• using a minimum number of protons per spot constraint, computing a respective minimum distance between spots for a portion of a field that overlaps with the TV structure and a portion of the field that overlaps with the OAR structure;
• and
• applying a rendering process to convert the density maps for each of the portions into a set of points;
• and
• using the set of points and the minimum distance between spots computed, determining a respective spot map for each of the portions.

A computer implemented method of determining spot positioning for each field associated with a target volume (TV), said method comprising:

• accessing dose volume constraints and information associated with contours associated with a TV structure and an associated organ at risk (OAR) structure;
• using the dose volume constraints and the information associated with the contours, determining a respective density map for each of the structures;
• using a minimum number of protons per spot constraint, computing a minimum distance between spots for a portion of a field that overlaps with the TV structure and a portion of the field that overlaps with the OAR structure;
• and
• applying a rendering process to convert the density maps for each of the portions into a set of points;
• and
• using the set of points and the minimum distance between spots computed, determining a spot map for each of the portions.