Pericardial Effusion during Proton Therapy in a Patient with Chemorefractory Hodgkin Lymphoma.

We present a case of recurrent pericardial effusion presenting during proton therapy in a 24-year-old female receiving mediastinal treatment for classical Hodgkin lymphoma. Pericardial effusion is typically considered an event accompanying lymphoma diagnosis or as a subacute or late effect of radiotherapy. Rarely has it been described as occurring during radiation treatment with photon-based radiotherapy, let alone proton therapy. It is unclear what underlying cause triggered recurrent effusion in this patient. Identifying and managing pericardial effusion during treatment delivery is important to consider as it may affect radiation dosimetry, particularly with proton therapy. Doing so will help ensure patients receive optimal treatment and minimize the risks of morbidity and mortality.

Using Robust Optimization for Skin Flashing in Intensity Modulated Radiation Therapy for Breast Cancer Treatment: A Feasibility Study.

PURPOSE: To study the feasibility and the effectiveness of a novel implementation of robust optimization on 2 sets of computed tomography (CT) data simultaneously for skin flashing in intensity modulated radiation therapy for breast cancer. METHOD AND MATERIALS: Five patients who received treatment to the breast and regional lymphatics were selected for this study. For each patient, 3 plans were generated using 3 different skin-flashing methods, including (1) a manual flash plan with optimization on the nominal planning target volume (PTV) not extending beyond the skin that required manually postplanning the opening of the multi-leaf collimator and jaw to obtain flash; (2) an expanded PTV plan with optimization on an expanded PTV that included the target in the air beyond the skin; and (3) a robust-optimized (RO) plan using robust optimization that simultaneously optimizes on the nominal CT data set and a simulated geometry error CT data set. The feasibility and the effectiveness of the robust optimization approach was investigated by comparing it with the 2 other methods. The robustness of the plan against target position variations was studied by simulating 0-, 5-, 10-, and 15-mm geometry errors. RESULTS: The RO plans were the only ones able to meet acceptable criteria for all patients in both the nominal and simulated geometry error scenarios. The expanded PTV plans developed major deviation on the maximum dose to the PTV for 1 patient. For the manual flash plans, every patient developed major deviation either on 95% of the dose to the PTV or the maximum dose to the PTV in the simulated geometry error scenarios. The RO plan demonstrated the best robustness against the target position variation among the 3 methods of skin flashing. The doses to the lung and heart were comparable for all 3 planning techniques. CONCLUSION: Using robust optimization for skin flash in breast intensity modulated radiation therapy planning is feasible. Further investigation is warranted to confirm the clinical effectiveness of this novel approach.

Protons offer reduced bone marrow, small bowel, and urinary bladder exposure for patients receiving neoadjuvant radiotherapy for resectable rectal cancer.

BACKGROUND: To assess the potential benefit of proton therapy (PT) over photon therapy, we compared 3-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT), and PT plans in patients undergoing neoadjuvant chemoradiation for resectable rectal cancer at our institution. METHODS: Eight consecutive patients with resectable (T2-T3) rectal cancers underwent 3DCRT, IMRT, and 3-dimensional conformal PT treatment planning. Initial target volumes (PTV1) were contoured using the Radiation Therapy Oncology Group anorectal atlas guidelines. Boost target volumes (PTV2) consisted of the gross rectal tumor plus a uniform 2-cm expansion. Plans delivered 45 Gray (Gy) or Cobalt Gray Equivalent (CGE) to the PTV1 and a 5.4-Gy (CGE) boost to the PTV2. Ninety-five percent of the PTVs received 100% of the target dose and 100% of the PTVs received 95% of the target dose. Standard normal-tissue constraints were utilized. Wilcoxon paired t-tests were performed to compare various dosimetric points between the 3 plans for each patient. RESULTS: All plans met all normal-tissue constraints and were isoeffective in terms of PTV coverage. The proton plans offered significantly reduced median normal-tissue exposure over the 3DCRT and IMRT plans with respect to pelvic bone marrow at the V5Gy, V10Gy, V15Gy, and V20Gy levels and the small bowel space at the V10Gy and V20Gy levels. The proton plans also offered significantly reduced median normal-tissue exposure over the 3DCRT plans with respect to the small bowel at the V30Gy and V40Gy levels and the urinary bladder at the V40Gy level. CONCLUSIONS: By reducing bone marrow exposure, PT may reduce the acute hematologic toxicity of neoadjuvant chemoradiation and increase the likelihood of uninterrupted chemotherapy delivery. Bone marrow sparing may also facilitate the delivery of salvage chemotherapy for patients who subsequently develop hematogenous metastasis. Reduced small bowel exposure using PT may also reduce toxicity and possibly facilitate the use of more-aggressive chemotherapy with radiotherapy.