Date Approved


Graduate Degree Type


Degree Name

Medical Dosimetry (M.S.)

Degree Program

Allied Health Sciences

First Advisor

Bethany S. Marshall MS CMD, RT(T)

Second Advisor

Perry Johnson, PhD

Third Advisor

Kevin Kirby CMD, RT(R)(T)

Academic Year



Proton arc therapy (PAT) will become widely available soon. It is crucial to determine if this technique and the associated calculation algorithms provided by treatment planning system vendors compete favorably with established proton therapy techniques like intensity modulated proton therapy (IMPT) and the Monte Carlo dose calculation algorithm used to compute IMPT doses in today’s clinic. RaySearch Laboratories have produced a modified Monte Carlo algorithm called ELSA.

ELSA stands for early layer spot assignment and is RaySearch Laboratories proposed solution to reduce optimization time during treatment planning for PAT. This research study will look at proton plan robustness to determine if PAT planned with the ELSA algorithm competes favorably with IMPT planned with Monte Carlo. Proton plan robustness, while not standardized across all clinics, is well known and widely used in various forms at proton therapy centers across the world. Robust optimization techniques can be utilized during treatment planning to ensure better target coverage and organ at risk (OAR) sparing during daily treatments. Once planning is complete, physicists often evaluate proton plan robustness to gauge treatment plan safety for patient treatment given the range uncertainties and variations in linear energy transfer (LET) that are inherent with proton beam therapy.

In this study, PAT plans showed similar robustness to IMPT plans and demonstrated superior clinical target volume (CTV) coverage for worst-case scenarios, indicating its potential advantage in ensuring adequate dose delivery. The findings also suggested that both PAT and IMPT plans performed comparably in handling uncertainties and patient anatomy variations. These results align with previous research indicating potential benefits of PAT in conformality and reducing low-dose radiation exposure to normal tissues. However, the authors acknowledged the need for further research due to potential sample size limitations.

Included in

Oncology Commons