Breast Proton Therapy Treatment and Optimization Recommendations
R Ger*, K Sheikh, B Floreza, E Gogineni, V Croog, H Li, J Wright, Johns Hopkins Medicine, Washington, DC
Presentations
TU-D930-IePD-F4-2 (Tuesday, 7/12/2022) 9:30 AM - 10:00 AM [Eastern Time (GMT-4)]
Exhibit Hall | Forum 4
Purpose: To provide recommendations for robustness criteria, daily imaging, and QACT frequency for breast cancer patients treated with proton therapy.
Methods: All patients treated for localized breast cancer at the Johns Hopkins Proton Center between November 2019 and February 2022 were eligible for inclusion. Daily shift information was extracted for each patient and examined through control charts. If an adaptive plan was used, the time to re-plan was recorded. 3mm and 5mm setup uncertainty was used to calculate robustness. Each patient’s QACTs were assessed to determine if they fell within the initial robustness range for breast/chest wall and lymph node target coverage.
Results: Sixty-six patients were included in this study: 19 intact breast patients, 25 non-reconstructed chest wall patients, and 22 patients with implants. 16%, 13%, and 41% of breast, chest wall, and implant patients had a re-plan, respectively, with an average time to re-plan of 16, 11, and 6 days, respectively. Only patients with implants required 2 adaptive plans. Daily shift data showed large variation and did not correlate with plan adaptation. Patients without adaptive plans had QACTs with DVH metrics within robustness more frequently than those with adaptive plans. Under 3 mm robustness for patients that did not have an adaptive plan, 100%, 100%, and 91% of patients had QACTs within robustness for the axilla, internal mammary nodes, and supraclavicular nodes, while 60%, 55%, and 60% of patients with an adaptive plan had QACTs within robustness, respectively. 5mm setup uncertainty did not significantly improve this.
Conclusion: We recommend utilizing daily CBCT due to the large variation in daily setup with 3 mm setup uncertainty in robustness analysis. If daily CBCT imaging is not available, then larger setup uncertainty should be used. Two QACTs should be conducted during treatment if the patient has implants, otherwise, one QACT is sufficient.
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