Pencil Beam Scanning Proton Therapy for Pregnant Patients With Brain and Head and Neck Cancers.

PURPOSE: When radiation therapy is medically necessary for pregnant patients, photon-based treatments (XRT) have traditionally been used, whereas proton radiation therapy (PRT) is avoided due to concerns about neutron dose. This retrospective study analyzes pregnant patients treated with XRT and models the equivalent dose that would have been delivered to the fetus with proton radiation compared with XRT. The purpose of this work is to provide a comprehensive analysis of pencil beam scanning proton therapy (PBS-PRT) for pregnant patients and to evaluate whether PBS-PRT should be the new standard of practice for treating pregnant patients with brain and head and neck cancers. METHODS AND MATERIALS: PBS-PRT plans were made for seven pregnant patients who received XRT: four treated for brain tumors and three for head and neck tumors. Measurements were performed with the patient plans using an anthropomorphic phantom and Wendi-2 meter placed at the phantom's abdomen. Patient-specific measurements were used to determine the total fetal equivalent dose from PBS-PRT compared with XRT. Imaging dose was also evaluated with a Fluke 451 dose meter. RESULTS: The average measured fetal equivalent dose, accounting for photons and neutrons, for the brain plans was 0.4 mSv for PBS-PRT and 7 mSv for XRT. For the head and neck plans, it was 6 mSv and 90 mSv for PBS-PRT and XRT, respectively. The PBS-PRT plans were preferred by the physicians for both tumor coverage and normal-tissue sparing. Daily imaging added between 0.05 and 1.5 mSv to the total dose. CONCLUSIONS: This retrospective study showed that when treating brain or head and neck cancers in pregnant patients, fetal equivalent dose is reduced by approximately a factor of 10 with PBS-PRT compared with XRT without making any compromises in treatment planning objectives. These results support a change of practice to using PBS-PRT as the new standard for treating pregnant patients with brain or head and neck tumors compared with XRT.

Proton Whole-Lung Irradiation: Initial Report of Outcomes.

PURPOSE: Whole-lung irradiation is typically used in pediatric patients to decrease the risk of future lung metastases, but radiation dose to normal tissue is associated with long-term risks. Proton whole-lung irradiation (PWLI) provides an opportunity to decrease radiation dose to normal tissue and potentially decrease late toxicity. METHODS AND MATERIALS: This retrospective study included patients treated with spot-scanning PWLI at a single institution. Toxicity and oncologic outcomes were reviewed. Intensity modulated radiation therapy (IMRT) plans were created prospectively or retrospectively for dosimetric comparisons. Simple paired t tests were performed to assess differences between IMRT and PWLI dosimetric parameters. RESULTS: Twelve patients treated with PWLI were included in this study. Median age was 15 years (range, 3-34). Most (75%) had Ewing sarcoma. Most (92%) received 15 Gy in 10 fractions PWLI, and 3 (25%) received a focal pulmonary boost. Median follow-up was 16.5 months (range, 0-40.4 months). At last follow-up, 1 patient died of disease, while 11 were still alive (7 without disease, 4 with ongoing disease). During and immediately after treatment, 5 patients developed fatigue, 2 patients developed cough, and 1 patient developed nausea. Each treatment-related adverse event was Common Terminology Criteria for Adverse Events (version 5.0) grade 1 and resolved within 3 weeks of treatment completion. No patients have experienced clinical or radiographic pneumonitis or evidence of clinically apparent cardiac toxicity. Compared with IMRT plans, PWLI decreased mean dose to the heart, coronary artery, cardiac valve, left ventricle, aorta, breast, esophagus, kidney, liver, pancreas, thyroid, stomach, and spleen (all P < .001), without sacrificing target coverage. CONCLUSIONS: PWLI is feasible to deliver, decreases dose to normal tissue compared with IMRT, and appears to be well-tolerated. PWLI provides potential for decreased late toxicity and merits further investigation.

Clinical efficacy and safety of a highly conformal, supine, hybrid forward and inverse planned intensity modulated radiation therapy technique for craniospinal irradiation.

PURPOSE: To demonstrate the clinical efficacy and safety of a highly conformal, supine, hybrid forward and inverse planned intensity modulated radiation therapy (IMRT) technique for photon craniospinal irradiation (CSI). METHODS: Patients who received supine, hybrid IMRT CSI from 2009 to 2014 were included in this retrospective review. Clinical target volume (CTV) was defined as intracranial contents and thecal sac, including nerve roots. Dose was prescribed such that >99% of CTV received >99% of prescription and >95% of the planning target volume received >95% of prescription, with no attempt to include vertebral bodies. Lateral fields were utilized at the cranium and upper cervical spine. Spine fields were either single posterior or 2-3 obliques. Plans were generated with a hybrid of forward and inverse planned IMRT. Inferior borders of the cranium fields and superior border of the lower spine field were designed with 6-15 cm long, gradual dose gradients by sequential closing of multileaf collimator leaves using forward planned multiple static segment IMRT delivery. The sliding window upper spine IMRT field was created by the inverse planning system to match gradients of the brain and lower spine fields. The lower spine field gradient was similarly completed. RESULTS: The cohort consisted of 34 patients. Median CSI dose was 36 Gy (range: 18-39.6 Gy). With a median follow up of 59.4 months, there were no isolated recurrences or spinal myelopathies at CTV margins or field gradients. Eleven patients had recurrence, all of which were intracranial. CONCLUSIONS: Our hybrid forward and inverse planned IMRT supine CSI technique did not result in any isolated recurrences or myelopathies at CTV margins or field gradients. This suggests our target volumes and blended gradients are appropriate for highly conformal three-dimensional planning.