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Background: We investigated the clinical outcomes of involved‐field high‐dose (≥66 Gy) chemoradiotherapy (CRT) combined with respiratory motion management for esophageal squamous cell carcinoma (ESCC). Methods: Patients who underwent definitive CRT for histologically confirmed ESCC in our department between 2012 and 2018 were retrospectively analyzed. Respiratory motion management strategies included breath‐holding (63%) and mask immobilization (29%) based on individual measurements of respiratory tumor motion using radiographic fluoroscopy with endoscopically placed clip markers as landmarks. We evaluated patient characteristics, treatment efficacy, failure patterns, and toxicities. Results: We enrolled 35 patients with a prescribed dose of 66–70 Gy in 33–35 fractions. The overall response rate within 6 months post‐CRT was 94.3%; the median follow‐up period for survivors was 43 months. The 2‐year overall survival (OS), progression‐free survival, and locoregional failure‐free survival rates were 51.4%, 42.9%, and 42.9%, respectively. A significant difference in OS was observed between patients with and without esophageal fistulas after CRT (p = 0.002, log‐rank test). Disease failure occurred in 16 patients (45.7%), including one (2.9%) with out‐of‐field regional nodal failure. Major grade 3 or higher toxicities included decreased white blood cell count (48.6%), neutrophil count (34.3%), and esophageal stenosis (31.4%). No grade 3 or higher cardiopulmonary toxicities were observed. Bronchial/tracheal tumor compression and a higher radiotherapy dose (70 Gy) were significantly correlated with esophageal fistulas. Conclusion: Involved‐field high‐dose CRT with respiratory motion management may be a feasible treatment option for ESCC. However, a comprehensive assessment of esophageal fistula risk is required to identify suitable candidates. [ABSTRACT FROM AUTHOR]

Although stereotactic body radiotherapy (SBRT) is a curative treatment option for stage I non‐small cell lung cancer (NSCLC), limited data are available regarding chest wall (CW) toxicities during an extended follow‐up of over 10 years. We report an unusual case of a bone tumor‐like CW mass lesion with pathological rib fractures observed 13 years after SBRT for peripheral lung cancer. Despite the initial suspicion of radiation‐induced sarcoma, a subsequent incisional biopsy revealed no evidence of malignancy, and a definitive diagnosis of osteonecrosis was made. Thus, long‐term observation of over 10 years is required to identify late chronic complications following SBRT. [ABSTRACT FROM AUTHOR]

Purpose of this study is to evaluate patient characteristics, treatments and outcomes in bone metastasis radiotherapy practice. Patients for whom radiotherapy for bone metastasis was planned at 26 institutions in Japan between December 2020 and March 2021 were consecutively registered in this prospective, observational study. Study measures included patient characteristics, pain relief, skeletal-related events (SREs), overall survival and incidence of radiation-related adverse events. Pain was evaluated using a numerical rating scale (NRS) from 0 to 10. Irradiated dose was analyzed by the biologically effective dose (BED) assuming α/β = 10. Overall, 232 patients were registered; 224 patients and 302 lesions were fully analyzed. Eastern Cooperative Oncology Group Performance Status was 0/1/2/3/4 in 23%/38%/22%/13%/4%; 59% of patients had spinal metastases and 84% had painful lesions (NRS ≥ 2). BED was <20 Gy (in 27%), 20–30 Gy (24%), 30–40 Gy (36%) and ≥ 40 Gy (13%); 9% of patients were treated by stereotactic body radiotherapy. Grade 3 adverse events occurred in 4% and no grade 4–5 toxicity was reported. Pain relief was achieved in 52% at 2 months. BED is not related to pain relief. The cumulative incidence of SREs was 6.5% (95% confidence interval (CI) 3.1–9.9) at 6 months; no factors were significantly associated with SREs. With spinal lesions, 18% of patients were not ambulatory at baseline and 50% of evaluable patients in this group could walk at 2 months. The 6-month overall survival rate was 70.2% (95% CI 64.2–76.9%). In conclusion, we report real-world details of radiotherapy in bone metastasis. [ABSTRACT FROM AUTHOR]

Background: Surface‐guided radiotherapy (SGRT) is adopted by several institutions; however, reports on the phantoms used to assess the precision of the SGRT setup are limited. Purpose: The purpose of this study was to develop a phantom to verify the accuracy of the irradiation position during skin mark‐less SGRT. Methods: An acrylonitrile butadiene styrene (ABS) plastic cube phantom with a diameter of 150 mm on each side containing a dummy target of 15 mm and two types of body surface‐shaped phantoms (breast/face shape) that could be attached to the cube phantom were fabricated. Films can be inserted on four sides of the cubic phantom (left, right, anterior and posterior), and the center of radiation can be calculated by irradiating the dummy target with orthogonal MV beams. Three types of SGRT using a VOXELAN‐HEV600M (Electronics Research&Development Corporation, Okayama, Japan) were evaluated using this phantom: (i) SGRTCT—a SGRT set‐up based solely on a computed tomography (CT)‐reference image. (ii) SGRTCT + CBCT—a method where cone beam computed tomography (CBCT) matching was performed after SGRTCT. (iii) SGRTScan—a resetup technique using a scan reference image obtained after completing the (ii) step. Results: Both the breast and face phantoms were recognized in the SGRT system without problems. SGRTScan ensure precision within 1 mm/1° for breast and face verification, respectively. All SGRT methods showed comparable rotational accuracies with no significant disparities. Conclusions: The developed phantom was useful for verifying the accuracy of skin mark‐less SGRT position matching. The SGRTScan demonstrated the feasibility of achieving skin‐mark less SGRT with high accuracy, with deviations of less than 1 mm. Additional research is necessary to evaluate the suitability of the developed phantoms for use in various facilities and systems. This phantom could be used for postal surveys in the future. [ABSTRACT FROM AUTHOR]

Purpose: Predicting recurrence following stereotactic body radiotherapy (SBRT) for non‐small cell lung cancer provides important information for the feasibility of the individualized radiotherapy and allows to select the appropriate treatment strategy based on the risk of recurrence. In this study, we evaluated the performance of both machine learning models using positron emission tomography (PET) and computed tomography (CT) radiomic features for predicting recurrence after SBRT. Methods: Planning CT and PET images of 82 non‐small cell lung cancer patients who performed SBRT at our hospital were used. First, tumors were delineated on each CT and PET of each patient, and 111 unique radiomic features were extracted, respectively. Next, the 10 features were selected using three different feature selection algorithms, respectively. Recurrence prediction models based on the selected features and four different machine learning algorithms were developed, respectively. Finally, we compared the predictive performance of each model for each recurrence pattern using the mean area under the curve (AUC) calculated following the 0.632+ bootstrap method. Results: The highest performance for local recurrence, regional lymph node metastasis, and distant metastasis were observed in models using Support vector machine with PET features (mean AUC = 0.646), Naive Bayes with PET features (mean AUC = 0.611), and Support vector machine with CT features (mean AUC = 0.645), respectively. Conclusions: We comprehensively evaluated the performance of prediction model developed for recurrence following SBRT. The model in this study would provide information to predict the recurrence pattern and assist in making treatment strategies. [ABSTRACT FROM AUTHOR]

The purpose of this study is to evaluate the detection accuracy of a 3-dimensional (3D) body scanner, VOXELAN, in surface-guided radiotherapy (SGRT) of each part of the human body using a whole-body human phantom. We used A Resusci Anne was used as the whole-body phantom. The detection accuracy of VOXELAN in a radiotherapy treatment room with a linear accelerator (LINAC) was evaluated for two reference images: reconstruction of the planning computed tomography (CT) image (CT reference) and scanning by VOXELAN before the treatment (scan reference). The accuracy of the translational and rotational directions was verified for four treatment sites (open face shell, breast, abdomen, and arm), using the magnitude of the 6D robotic couch movement as the true value. Our results showed that the detection accuracy improved as the displacement from the reference position decreased for all the sites. Using the scan reference, the average accuracy of the translational and rotational axes was within 1.44 mm and 0.41°, respectively, for all sites except the arms. Similarly, using the CT reference, the average accuracy was within 2.45 mm and 1.35°, respectively. Additionally, it was difficult for both reference images to recognize misalignment of the arms. In conclusion we discovered that VOXELAN achieved a high detection accuracy for the head with an open face shell, chest, and abdomen, indicating that the system is useful in a clinical setting. However, it is necessary to pay attention to location matching for areas with few features, such as surface irregularities and potential errors, when the reference image is created from CT. [ABSTRACT FROM AUTHOR]

Abstract Background As stereotactic body radiotherapy (SBRT) is a highly dose-dense radiotherapy, adverse events of neighboring normal tissues are a major concern. This study thus aimed to clarify the frequency and degree of clinical symptoms in patients with rib fractures after SBRT for primary lung cancer and to reveal risk factors for rib fracture. Appropriate α/β ratios for discriminating between fracture and non-fracture groups were also investigated. Methods Between November 2001 and April 2009, 177 patients who had undergone SBRT were evaluated for clinical symptoms and underwent follow-up thin-section computed tomography (CT). The time of rib fracture appearance was also assessed. Cox proportional hazard modeling was performed to identify risk factors for rib fracture, using independent variables of age, sex, maximum tumor diameter, radiotherapeutic method and tumor-chest wall distance. Dosimetric details were analyzed for 26 patients with and 22 randomly-sampled patients without rib fracture. Biologically effective dose (BED) was calculated with a range of α/β ratios (1–10 Gy). Receiver operating characteristics analysis was used to define the most appropriate α/β ratio. Results Rib fracture was found on follow-up thin-section CT in 41 patients. The frequency of chest wall pain in patients with rib fracture was 34.1% (14/41), and was classified as Grade 1 or 2. Significant risk factors for rib fracture were smaller tumor-chest wall distance and female sex. Area under the curve was maximal for BED at an α/β ratio of 8 Gy. Conclusions Rib fracture is frequently seen on CT after SBRT for lung cancer. Small tumor-chest wall distance and female sex are risk factors for rib fracture. However, clinical symptoms are infrequent and generally mild. When using BED analysis, an α/β ratio of 8 Gy appears most effective for discriminating between fracture and non-fracture patients.