Author: Lordina Owusuwaa Oheneferewoo Asibey, Rachel B. Ger, Heng Li 👨🔬
Affiliation: Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Johns Hopkins University, Howard University 🌍
Purpose: Treatment of cancer patients with proton therapy requires robust optimization applications to be able to provide adequate target coverage whiles sparing healthy tissues. Our goal was to evaluate the robustness optimization applied clinically for thoracic cancer patients and provide recommendations for optimal robustness criteria.
Methods: Treatment plans for thoracic cancer patients treated at the Johns Hopkins Proton Therapy Center were analyzed. Clinical robust margins of 3mm or 5mm were applied to account for setup uncertainties alongside a 3.5% range uncertainty. The target and organs at risks’ clinical goal coverage for the Quality Assurance CT scans (QACTs) of the patients were evaluated and the differences between the nominal plans and the QACTs were also analyzed.
Results: The proportion of QACT plans that met both clinical objectives and robustness standards was observed to be 74.73%. A comparative analysis of the nominal plans and the QACTs revealed that 1.18% of the total QACTs performed better than the clinical plans, with 29.57% matching the nominal plans, and 79.26% falling below the nominal plans.
Conclusion: The Proton therapy treatment for thoracic cancer patients exhibited effective robustness with a great amount of target coverage and good normal organ sparing observed across majority of the patients. Further investigation on the target coverages that were found to be below the robustness criteria is recommended. Also, refining robustness parameters further can enhance precision and minimize risks to healthy tissues, offering valuable insights for future treatment protocols.