Purpose: The purpose of this study was to develop automated planning for wholebrain radiation therapy (WBRT) using a U-net-based deep-learning model for predicting the multileaf collimator (MLC) shape bypassing the contouring processes. Methods: A dataset of 55 cases, including 40 training sets, five validation sets, and 10 test sets, was used to predict the static MLC shape. The digitally reconstructed radiograph (DRR) reconstructed from planning CT images as an input layer and the MLC shape as an output layer are connected one-to-one via the U-net modeling. The Dice similarity coefficient (DSC) was used as the loss function in the training and ninefold cross-validation. Dose-volume-histogram (DVH) curves were constructed for assessing the automatic MLC shaping performance. Deep-learning (DL) and manually optimized (MO) approaches were compared based on the DVH curves and dose distributions.Results: The ninefold cross-validation ensemble test results were consistent with DSC values of 94.6 ± 0.4 and 94.7 ± 0.9 in training and validation learnings, respectively. The dose coverages of 95% target volume were (98.0 ± 0.7)% and (98.3 ± 0.8)%, and the maximum doses for the lens as critical organ-at-risk were 2.9 Gy and 3.9 Gy for DL and MO, respectively. The DL technique shows the consistent results in terms of the DVH parameter except for MLC shaping prediction for dose saving of small organs such as lens.Conclusions: Comparable with the MO plan result, the WBRT plan quality obtained using the DL approach is clinically acceptable. Moreover, the DL approach enables WBRT auto-planning without the time-consuming manual MLC shaping and target contouring.whole-brain radiation therapy, deep learning, automatic planning | INTRODUCTIONMetastatic brain cancer is the most common type of intracranial tumor. 1 From common primary cancer sites such as lung, breast, and melanoma, brain metastasis occurs in 15% to 40% of the cancer patients. 2,3 The treatment of metastatic brain tumors depends on the number of metastatic tumors, extracranial tumor status, and performance status. [4][5][6] Currently, whole-brain radiation therapy (WBRT) is considered a well-established treatment for patients with multiple brain metastases.

Pediatric Hodgkin lymphoma (pHL) is a rare disease in Korea with a crude incidence of 1.3 per million among ages 0 to 14 years [1]. In the United States, pHL accounts for nearly 5%-10% of pediatric malignancies, with approximately 1,700 newly diagnosed cases among children under 20 years old [2]. Studies conducted in western countries report that pHL is a highly curable disease with 5-year event-free survival (EFS) and overall survival (OS) exceeding Purpose: To analyze the clinical outcomes and long-term toxicity of pediatric patients with Hodgkin lymphoma after combined-modality treatment (CMT) with involved-field or involved-nodal radiotherapy (RT). Materials and Methods: We retrospectively reviewed the records of 27 pediatric Hodgkin lymphoma patients who received CMT at a single institution between January 1990 and July 2017. Patients with stage I-III received a heterogeneous chemotherapy regimen depending on their risk group followed by 19.8-36 Gy RT, with the dose based on their response to the chemotherapy before RT. An optional 9-20 Gy boost was delivered to residual sites. The risk group was determined based on the initial stage, the presence of bulky disease, and any B symptoms. We evaluated overall survival, event-free survival, and long-term toxicities. Results: A total of 27 patients completed the CMT. At a median follow-up of 125 months (range, 9 to 337 months), the estimated 5-year event-free survival and overall survival were 88.9% and 96.3%, respectively. Late symptomatic cardiopulmonary toxicity was not observed, and only one patient was positive on a subclinical obstructive pulmonary function test. The incidence of hypothyroidism was 58.3% among 12 patients with an available thyroid function test. There was one papillary thyroid cancer diagnosed 7.2 years after treatment. Conclusion: CMT for pediatric Hodgkin lymphoma with involved-field and involved-nodal RT achieved an excellent survival with only modest long-term toxicity. Smaller-field RT seemed to decrease long-term toxicities and had good local control.

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