Clinical Flow Improvement by Direct Conversion of Proton Plans across Different Platforms

Abstract

<h3>Purpose/Objective(s)</h3> For proton therapy plans, switching proton machines without re-optimization can greatly improve the clinical efficiency, when proton machines belong to different platforms. This study focused on machine switching efficiency between Proteus-1 and Proteus-plus platforms by modeling a Proteus-1 proton machine with built-in range shifter (P1RS) for direct recalculation of treatment plans between P1 and universal nozzle of Proteus-plus (P+US) systems. <h3>Materials/Methods</h3> For institutions with multiple platform proton machines (i.e., P+ to P1), re-planning is usually required if a patient needs to be moved from P+ to P1 machines due to their different spot sizes. This usually requires re-planning of the patient and creates significant time delay when one machine is down or overloaded. We are proposing commissioning a P1 machine model use built-in range shifter (P1RS) with snout position fixed at 45cm upstream from isocenter. The in-air spot size and PDD of the P1RS are compared to those of the P+US. The P+ patient plans are recalculated using P1RS machine directly with both pencil beam and Monte Carlo dose engines. <h3>Results</h3> The P1RS machine model has similar in-air spot size as those of P+US (see Table). There are noticeable differences between the PDDs of the two models. For patient plan with field size less than 20cm by 24cm, preliminary investigation of direct conversion of treatment plans between the two machine models indicates that it is feasible. <h3>Conclusion</h3> P1 model with a built-in range shifter can simulate a P+US system. Direct recalculation of treatment plan between the two systems is feasible with acceptable dosimetric differences and could increase machine switching capabilities and improve clinical flow efficiency.