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The heterogeneous movement of liquid water through the snowpack during precipitation and snowmelt leads to complex liquid water distributions that are important for avalanche and runoff forecasting. We reproduced the formation of capillary barriers and the development of preferential flow through snow using a three-dimensional water transport model, which was then validated using laboratory experiments of liquid water infiltration into layered, initially dry snow. Three-dimensional simulations assumed the same column shape and size, grain size, snow density, and water input rate as the laboratory experiments. Model evaluation focused on the timing of water movement, thickness of the upper layer affected by ponding, water content profiles and wet snow fraction. Simulation results showed that the model reconstructs relevant features of capillary barriers, including ponding in the upper layer, preferential infiltration far from the interface, and the timing of liquid water arrival at the snow base. In contrast, the area of preferential flow paths was usually underestimated and consequently the averaged water content in areas characterized by preferential flow paths was also underestimated. Improving the representation of preferential infiltration into initially dry snow is necessary to reproduce the transition from a dry-snow-dominant condition to a wet-snow-dominant one, especially in long-period simulations.

Data of liquid water flow around a capillary barrier in snow are still limited. To gain insight into this process, we carried out observations of dyed water infiltration in layered snow at 0 °C during cold laboratory experiments. We considered three different finer-over-coarser textures and three different water input rates. By means of visual inspection, horizontal sectioning, and measurements of liquid water content (LWC), capillary barriers and associated preferential flow were characterized. The flow dynamics of each sample were also simulated solving the Richards equation within the 1-D multi-layer physically based snow cover model SNOWPACK. Results revealed that capillary barriers and preferential flow are relevant processes ruling the speed of water infiltration in stratified snow. Both are marked by a high degree of spatial variability at centimeter scale and complex 3-D patterns. During unsteady percolation of water, observed peaks in bulk volumetric LWC at the interface reached ∼ 33–36 vol % when the upper layer was composed by fine snow (grain size smaller than 0.5 mm). However, LWC might locally be greater due to the observed heterogeneity in the process. Spatial variability in water transmission increases with grain size, whereas we did not observe a systematic dependency on water input rate for samples containing fine snow. The comparison between observed and simulated LWC profiles revealed that the implementation of the Richards equation reproduces the existence of a capillary barrier for all observed cases and yields a good agreement with observed peaks in LWC at the interface between layers.

The runoff from a snow cover during spring snowmelt or rain-on-snow events is an important factor in the hydrological cycle. In this study, three water balance schemes for the 1 dimensional physically-based snowpack model SNOWPACK are compared to lysimeter measurements at two alpine sites with a seasonal snow cover, but with different climatological conditions: Weissfluhjoch (WFJ) and Col de Porte (CDP). The studied period consists of 14 and 17 yr, respectively. The schemes include a simple bucket-type approach, an approximation of Richards Equation (RE), and the full RE. The results show that daily sums of snowpack runoff are strongly related to a positive energy balance of the snow cover and therefore, all water balance schemes show very similar performance in terms of Nash-Sutcliffe efficiency (NSE) coefficients (around 0.63 and 0.72 for WFJ and CDP, respectively) and r2 values (around 0.83 and 0.72 for WFJ and CDP, respectively). An analysis of the runoff dynamics over the season showed that the bucket-type and approximated RE scheme release meltwater slower than in the measurements, whereas RE provides a better agreement. Overall, solving RE for the snow cover yields the best agreement between modelled and measured snowpack runoff, but differences between the schemes are small. On sub-daily time scales, the water balance schemes behave very differently. In that case, solving RE provides the highest agreement between modelled and measured snowpack runoff in terms of NSE coefficient (around 0.48 at both sites). At WFJ, the other water balance schemes loose most predictive power, whereas at CDP, the bucket-type scheme has an NSE coefficient of 0.39. The shallower and less stratified snowpack at CDP likely reduces the differences between the water balance schemes. Accordingly, it can be concluded that solving RE for the snow cover improves several aspects of modelling snow cover runoff, especially for deep, sub-freezing snow covers and in particular on the sub-daily time scales. The additional computational cost was found to be in the order of a factor of 1.5–2.

Background and Purpose: Free-breathing computed tomography (FBCT) used in treatment planning for lower thoracic (Th8-Th12) spine stereotactic body radiotherapy (SBRT) can cause deviations between planned and irradiated doses due to diaphragm movement (DM). This study analyzed the dosimetric impact of DM on lower thoracic spine SBRT., Materials and Methods: Data were collected from 19 patients who underwent FBCT and four-dimensional CT (4DCT) during the same session. The 4DCT data were divided into ten respiratory phases (0-90%), and an average CT (AveCT) was reconstructed from them. Using FBCT, target and normal tissues near the diaphragm were contoured and spine SBRT plans with 24-Gy doses in two fractions were created. These plans were applied to each phase of CT and AveCT, with doses recalculated using the same parameters. Actual treatment doses (Deformed AveCT) were estimated by accumulating doses across each 4DCT phase using deformable image registration on the AveCT. Dose-volume histogram (DVH) indices were compared between the FBCT, AveCT, 0% phase, 50% phase, and Deformed AveCT plans., Results: The mean differences in DVH indices for target and normal tissues were within 2.4 and 2.1%, respectively, when the diaphragm displacement was between -1.6 cm and 2.0 cm, as compared with FBCT. DM displacement showed moderate to strong correlations with DVH differences., Conclusion: Our results indicate that DM has a minor impact on DVH indices if the diaphragm remains within 1.5 cm of the FBCT position., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Associazione Italiana di Fisica Medica e Sanitaria. Published by Elsevier Ltd. All rights reserved.)

This study aimed to identify systematic errors in measurement-, calculation-, and prediction-based patient-specific quality assurance (PSQA) methods for volumetric modulated arc therapy (VMAT) on lung cancer and to standardize the gamma passing rate (GPR) by considering systematic errors during data assimilation. This study included 150 patients with lung cancer who underwent VMAT. VMAT plans were generated using a collapsed-cone algorithm. For measurement-based PSQA, ArcCHECK was employed. For calculation-based PSQA, Acuros XB was used to recalculate the plans. In prediction-based PSQA, GPR was forecasted using a previously developed GPR prediction model. The representative GPR value was estimated using the least-squares method from the three PSQA methods for each original plan. The unified GPR was computed by adjusting the original GPR to account for systematic errors. The range of limits of agreement (LoA) were assessed for the original and unified GPRs based on the representative GPR using Bland-Altman plots. For GPR (3%/2 mm), original GPRs were 94.4 ± 3.5%, 98.6 ± 2.2% and 93.3 ± 3.4% for measurement-, calculation-, and prediction-based PSQA methods and the representative GPR was 95.5 ± 2.0%. Unified GPRs were 95.3 ± 2.8%, 95.4 ± 3.5% and 95.4 ± 3.1% for measurement-, calculation-, and prediction-based PSQA methods, respectively. The range of LoA decreased from 12.8% for the original GPR to 9.5% for the unified GPR across all three PSQA methods. The study evaluated unified GPRs that corrected for systematic errors. Proposing unified criteria for PSQA can enhance safety regardless of the methods used., Competing Interests: Declarations. Ethics approval: This study (R1446) was approved by the Institutional Review Board of the Kyoto University Hospital on January 30, 2018. Competing interests: The authors have no relevant conflicts of interest to disclose., (© 2024. Australasian College of Physical Scientists and Engineers in Medicine.)

Atypical hemolytic uremic syndrome (aHUS) is a type of HUS. We herein report a case of aHUS triggered by pancreatitis in a patient with a heterozygous variant of membrane cofactor protein (MCP; P165S), a complement-related gene. Plasma exchange therapy and hemodialysis improved thrombocytopenia and anemia without leading to end-stage kidney disease. This MCP heterozygous variant was insufficient to cause aHUS on its own. Pancreatitis, in addition to a genetic background with a MCP heterozygous variant, led to the manifestation of aHUS. This case supports the "multiple hit theory" that several factors are required for the manifestation of aHUS.

Machine- and patient-specific quality assurance (QA) is essential to ensure the safety and accuracy of radiotherapy. QA methods have become complex, especially in high-precision radiotherapy such as intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT), and various recommendations have been reported by AAPM Task Groups. With the widespread use of IMRT and VMAT, there is an emerging demand for increased operational efficiency. Artificial intelligence (AI) technology is quickly growing in various fields owing to advancements in computers and technology. In the radiotherapy treatment process, AI has led to the development of various techniques for automated segmentation and planning, thereby significantly enhancing treatment efficiency. Many new applications using AI have been reported for machine- and patient-specific QA, such as predicting machine beam data or gamma passing rates for IMRT or VMAT plans. Additionally, these applied technologies are being developed for multicenter studies. In the current review article, AI application techniques in machine- and patient-specific QA have been organized and future directions are discussed. This review presents the learning process and the latest knowledge on machine- and patient-specific QA. Moreover, it contributes to the understanding of the current status and discusses the future directions of machine- and patient-specific QA., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.)

Background: For patient-specific quality assurance (PSQA) for small targets, the dose resolution can change depending on the characteristics of the dose calculation algorithms., Purpose: This study aimed to evaluate the influence of the dose calculation algorithms Acuros XB (AXB), anisotropic analytical algorithm (AAA), photon Monte Carlo (pMC), and collapsed cone (CC) on a helical diode array using volumetric-modulated arc therapy (VMAT) for small targets., Materials and Methods: ArcCHECK detectors were inserted with a physical depth of 2.9 cm from the surface. To evaluate the influence of the dose calculation algorithms for small targets, rectangular fields of 2×100, 5×100, 10×100, 20×100, 50×100, and 100×100 mm 2 were irradiated and measured using ArcCHECK with TrueBeam STx. A total of 20 VMAT plans for small targets, including the clinical sites of 19 brain metastases and one spine, were also evaluated. The gamma passing rates (GPRs) were evaluated for the rectangular fields and the 20 VMAT plans using AXB, AAA, pMC, and CC., Results: For rectangular fields of 2×100 and 5×100 mm 2 , the GPR at 3%/2 mm of AXB was < 50% because AXB resulted in a coarser dose resolution with narrow beams. For field sizes > 10×100 mm2, the GPR at 3%/2 mm was > 88.1% and comparable for all dose calculation algorithms. For the 20 VMAT plans, the GPRs at 3%/2 mm were 79.1 ± 15.7%, 93.2 ± 5.8%, 94.9 ± 4.1%, and 94.5 ± 4.1% for AXB, AAA, pMC, and CC, respectively., Conclusion: The behavior of the dose distribution on the helical diode array differed depending on the dose calculation algorithm for small targets. Measurements using ArcCHECK for VMAT with small targets can have lower GPRs owing to the coarse dose resolution of AXB around the detector area., (© 2024 The Authors. Journal of Applied Clinical Medical Physics is published by Wiley Periodicals, Inc. on behalf of The American Association of Physicists in Medicine.)

Intensive care units (ICUs) are designed for critically ill patients who often experience high mortality rates owing to the severity of their conditions. Although the primary goal is patient recovery, it is crucial to understand the quality of death in the ICU setting. Nevertheless, there is a notable lack of systematic reviews on measured death quality and its associated factors. This study aims to conduct a quantitative synthesis of evidence regarding the quality of death in the ICU and offers a comprehensive overview of the factors influencing this quality, including its relationship with the post-intensive care syndrome-family (PICS-F). A thorough search without any language restrictions across MEDLINE, CINAHL, PsycINFO, and Igaku Chuo Zasshi databases identified relevant studies published until September 2023. We aggregated the results regarding the quality of death care for patients who died in the ICU across each measurement tool and calculated the point estimates and 95% confidence intervals. The quantitative synthesis encompassed 19 studies, wherein the Quality of Dying and Death-single item (QODD-1) was reported in 13 instances (Point estimate: 7.0, 95% CI: 6.93-7.06). Patient demographic data, including age and gender, as well as the presence or absence of invasive procedures, such as life support devices and cardiopulmonary resuscitation, along with the management of pain and physical symptoms, were found to be associated with a high quality of death. Only one study reported an association between quality of death and PICS-F scores; however, no significant association was identified. The QODD-1 scale emerged as a frequently referenced and valuable metric for evaluating the quality of death in the ICU, and factors associated with the quality of ICU death were identified. However, research gaps persist, particularly regarding the variations in the quality of ICU deaths based on cultural backgrounds and healthcare systems. This review contributes to a better understanding of the quality of death in the ICU and emphasises the need for comprehensive research in this critical healthcare domain., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Naya et al.)

Patients after renal transplantation are susceptible to secondary malignancies, including anal squamous cell carcinoma. Chemoradiotherapy is the standard treatment for anal squamous cell carcinoma; however, typical irradiation fields for anal cancer encompass a transplanted kidney located in the right iliac fossa, which causes complete renal dysfunction. Thus, typical irradiation fields are not feasible for this population. Additionally, standard concurrent chemotherapy demonstrates nephrotoxicity. Here, we report a case of modified definitive chemoradiotherapy for a 40-year-old patient with locally advanced perianal squamous cell carcinoma after renal transplantation whose abdominoperineal resection was difficult because of a history of repeated open surgeries and long-term steroids. We modified the cranial side of the elective nodal irradiation fields in this case to spare the transplanted kidney, considering the lymph chains of the perianal tumor. We then used continuous 5-fluorouracil to avoid nephrotoxicity of mitomycin C, considering his life expectancy. Modified definitive chemoradiotherapy achieved complete remission with expected toxicities. Now, approximately five years after the procedure, the patient remains disease-free, preserving anal and renal function. Definitive chemoradiotherapy using modified irradiation fields and chemotherapy may be an option for patients with anal squamous cell carcinoma after renal transplantation., Competing Interests: Conflict of interestThe authors declare no conflicts of interest., (© The Author(s) under exclusive licence to The Japan Society of Clinical Oncology 2024. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.)

Background: Centrally located lung tumours present a challenge because of their tendency to exhibit symptoms such as airway obstruction, atelectasis, and bleeding. Surgical resection of these tumours often requires sacrificing the lungs, making definitive radiotherapy the preferred alternative to avoid pneumonectomy. However, the proximity of these tumours to mediastinal organs at risk increases the potential for severe adverse events. To mitigate this risk, we propose a dual-method approach: deep inspiration breath-hold (DIBH) radiotherapy combined with adaptive radiotherapy. The aim of this single-centre, single-arm phase II study is to investigate the efficacy and safety of DIBH daily online adaptive radiotherapy., Methods: Patients diagnosed with centrally located lung tumours according to the International Association for the Study of Lung Cancer recommendations, are enrolled and subjected to DIBH daily online adaptive radiotherapy. The primary endpoint is the one-year cumulative incidence of grade 3 or more severe adverse events, as classified by the Common Terminology Criteria for Adverse Events (CTCAE v5.0)., Discussion: Delivering definitive radiotherapy for centrally located lung tumours presents a dilemma between ensuring optimal dose coverage for the planning target volume and the associated increased risk of adverse events. DIBH provides measurable dosimetric benefits by increasing the normal lung volume and distancing the tumour from critical mediastinal organs at risk, leading to reduced toxicity. DIBH adaptive radiotherapy has been proposed as an adjunct treatment option for abdominal and pelvic cancers. If the application of DIBH adaptive radiotherapy to centrally located lung tumours proves successful, this approach could shape future phase III trials and offer novel perspectives in lung tumour radiotherapy., Trial Registration: Registered at the Japan Registry of Clinical Trials (jRCT; https://jrct.niph.go.jp/ ); registration number: jRCT1052230085 ( https://jrct.niph.go.jp/en-latest-detail/jRCT1052230085 )., (© 2024. The Author(s).)

The applications of Type B [anisotropic analytical algorithm (AAA) and collapsed cone (CC)] and Type C [Acuros XB (AXB) and photon Monte Carlo (PMC)] dose calculation algorithms in spine stereotactic body radiotherapy (SBRT) were evaluated. Water- and bone-equivalent phantoms were combined to evaluate the percentage depth dose and dose profile. Subsequently, 48 consecutive patients with clinical spine SBRT plans were evaluated. All treatment plans were created using AXB in Eclipse. The prescription dose was 24 Gy in two fractions at a 10 MV FFF on TrueBeam. The doses were then recalculated with AAA, CC and PMC while maintaining the AXB-calculated monitor units and beam arrangement. The dose index values obtained using the four dose calculation algorithms were then compared. The AXB and PMC dose distributions agreed with the bone-equivalent phantom measurements (within ±2.0%); the AAA and CC values were higher than those in the bone-equivalent phantom region. For the spine SBRT plans, PMC, AAA and CC were overestimated compared with AXB in terms of the near minimum and maximum doses of the target and organ at risk, respectively; the mean dose difference was within 4.2%, which is equivalent with within 1 Gy. The phantom study showed that the results from AXB and PMC agreed with the measurements within ±2.0%. However, the mean dose difference ranged from 0.5 to 1 Gy in the spine SBRT planning study when the dose calculation algorithms changed. Users should incorporate a clinical introduction that includes an awareness of these differences., (© The Author(s) 2023. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.)

Purpose: To evaluate the applicability of TRS-483 output correction factors (CFs) for small-field output factors (OFs) using different multi-leaf collimators (MLC) and field-shaping types., Methods: All measurements were performed on TrueBeam, TrueBeam STx, and Halcyon using 6 MV flattening filter-free energy. Four detectors, including CC01, CC04, microDiamond, and EDGE, were used. Nominal field sizes ranging from 1 × 1 to 4 × 4, and 10 × 10 cm 2 were used to measure small-field OFs at source-to-axis distance of 100 cm with a 0° gantry angle in a 3D water phantom. Further, the field-shaping types were defined using jaw collimator or MLC (five different configurations). A field size of 10 × 10 cm 2 was used as the reference for calculation of OFs obtained as ratio of detector readings (OF det ). The percentage difference and coefficient of variation of OF det and OF det corrected by applying CF were compared for each field size and configuration., Results: For OF det corrected by applying CF, the ranges of percentage difference and coefficient of variation in all configurations for ≥ 2 × 2 cm 2 fields were reduced from 1.2-2.2 to 0.8-1.3 percentage points (%pt) and from 0.5-1.0 to 0.4-0.7%, respectively. For 1 × 1 cm 2 field, the ranges of percentage difference and coefficient of variation were reduced from 3.3-5.7 to 1.2-2.2 %pt and from 2.2-3.7 to 0.8-1.1%, respectively., Conclusions: The CFs described in TRS-483 dosimetry protocol have broad applicability in reducing OF variations between detectors under different MLC and field-shaping types., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Introduction: Intraoperative three-dimensional (3D) imaging guide technology, such as the O-arm surgical imaging system, is a beneficial tool in spinal surgery that provides real-time 3D images of a patient's spine. This study aims to determine the exposure dose from intraoperative O-arm imaging., Methods: A consecutive retrospective review of all patients undergoing spinal surgery was conducted between June 2019 and August 2022. Demographic and operative data were collected from electronic medical records., Results: Intraoperative O-arm imaging was conducted in 206 (12.9%) of 1599 patients, ranging from one to 4 scans per patient (1.17±0.43 scans). Single O-arm imaging enabled navigation of seven vertebrae in the cervical spine, seven in the thoracic spine, five in the thoracolumbar spine, and four in the lumbar spine on average. The number of O-arm shots per surgery was 1.15±0.36, 1.06±0.24, 1.61±0.7, and 1.07±0.25 for cervical, thoracic, thoracolumbar, and lumbar spinal cases, respectively. The exposure doses represented by dose length products in single O-arm imaging were 377±19 mGy-cm, 243±22 mGy-cm, 378±38 mGy-cm, and 258±11 mGy-cm for cervical, thoracic, thoracolumbar, and lumbar spine cases, respectively. We observed a weak positive correlation between the number of fused spinal levels and the exposure dose., Conclusions: Intraoperative radiation exposure from O-arm imaging was lower than the national diagnostic reference levels in Japan established based on the International Commission on Radiological Protection publication, demonstrating its safety from the standpoint of radiological protection in most cases. In surgeries with a large range of fixations, such as corrective deformity surgery, the number of imaging sessions and the amount of intraoperative radiation exposure would increase, leading surgeons to pay attention to the risk of radiation in spinal surgery., Competing Interests: Conflicts of Interest: The authors declare that there are no relevant conflicts of interest., (Copyright © 2023 The Japanese Society for Spine Surgery and Related Research.)

Purpose: The aim of this study was to evaluate generalization ability of segmentation accuracy for limited FOV CBCT in the male pelvic region using a full-image CNN. Auto-segmentation accuracy was evaluated using various datasets with different intensity distributions and FOV sizes., Methods: A total of 171 CBCT datasets from patients with prostate cancer were enrolled. There were 151, 10, and 10 CBCT datasets acquired from Vero4DRT, TrueBeam STx, and Clinac-iX, respectively. The FOV for Vero4DRT, TrueBeam STx, and Clinac-iX was 20, 26, and 25 cm, respectively. The ROIs, including the bladder, prostate, rectum, and seminal vesicles, were manually delineated. The U 2 -Net CNN network architecture was used to train the segmentation model. A total of 131 limited FOV CBCT datasets from Vero4DRT were used for training (104 datasets) and validation (27 datasets); thereafter the rest were for testing. The training routine was set to save the best weight values when the DSC in the validation set was maximized. Segmentation accuracy was qualitatively and quantitatively evaluated between the ground truth and predicted ROIs in the different testing datasets., Results: The mean scores ± standard deviation of visual evaluation for bladder, prostate, rectum, and seminal vesicle in all treatment machines were 1.0 ± 0.7, 1.5 ± 0.6, 1.4 ± 0.6, and 2.1 ± 0.8 points, respectively. The median DSC values for all imaging devices were ≥0.94 for the bladder, 0.84-0.87 for the prostate and rectum, and 0.48-0.69 for the seminal vesicles. Although the DSC values for the bladder and seminal vesicles were significantly different among the three imaging devices, the DSC value of the bladder changed by less than 1% point. The median MSD values for all imaging devices were ≤1.2 mm for the bladder and 1.4-2.2 mm for the prostate, rectum, and seminal vesicles. The MSD values for the seminal vesicles were significantly different between the three imaging devices., Conclusion: The proposed method is effective for testing datasets with different intensity distributions and FOV from training datasets., (© 2023 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, LLC on behalf of The American Association of Physicists in Medicine.)

Background: Relugolix, an oral gonadotrophin-releasing hormone receptor antagonist, was launched in Japan in 2019. Although there have been several studies on relugolix for leiomyomas, few have focused on submucosal leiomyomas. Submucosal leiomyomas cause bleeding more frequently than leiomyomas in other locations. There is only one case report described a patient treated for a submucosal leiomyoma with relugolix who developed severe hemorrhage. However, it remains unclear which characteristics of submucosal leiomyomas can lead to severe hemorrhage. Thus, the aim of this study was to investigate the characteristics of submucosal leiomyomas that would cause severe hemorrhage when treated with relugolix., Methods: We retrospectively reviewed records of patients who underwent treatment for submucosal leiomyoma with relugolix (40 mg once daily for up to 6 months) in our institute between December 2019 and September 2021. We evaluated the clinical course and characteristics of submucosal leiomyoma in patients who developed severe hemorrhage., Results: A total of 17 patients were treated for submucosal leiomyoma with relugolix. Two patients developed severe hemorrhage and required emergent surgery and blood transfusions. Only those two of the 17 patients had a submucosal leiomyoma of the International Federation of Gynecology and Obstetrics (FIGO) type 0, which has a stalk. In the remaining 15 patients who had FIGO type 1 or 2 leiomyoma, hemorrhage did not occur., Conclusions: Our study suggests that the use of relugolix for FIGO type 0 leiomyomas may be associated with a risk of hemorrhage. However, relugolix may be a safe and effective treatment option for patients with FIGO type 1 or 2 leiomyomas., (© 2023. The Author(s).)

Background: Small-field dosimetry is challenging for radiotherapy dosimetry because of the loss of lateral charged equilibrium, partial occlusion of the primary photon source by the collimating devices, perturbation effects caused by the detector materials and their design, and the detector size relative to the radiation field size, which leads to a volume averaging effect. Therefore, a suitable tool for small-field dosimetry requires high spatial resolution, tissue equivalence, angular independence, and energy and dose rate independence to achieve sufficient accuracy. Recently, with the increasing use of combinations of coplanar and non-coplanar beams for small-field dosimetry, there is a need to clarify angular dependence for dosimetry where the detector is oriented at various angles to the incident beam. However, the effect of angular dependence on small-field dosimetry with coplanar and non-coplanar beams has not been fully clarified., Purpose: This study clarified the effect of angular dependence on small-field dosimetry with coplanar and non-coplanar beams using various detectors., Methods: Seven different detectors were used: CC01, RAZOR, RAZOR Nano, Pinpoint 3D, stereotactic field diode (SFD), microSilicon, and microDiamond. All measurements were taken using a TrueBeam STx with 6 MV and 10 MV flattening filter-free (FFF) energies using a water-equivalent spherical phantom with a source-to-axis distance of 100 cm. The detector was inserted in a perpendicular orientation, and the gantry was rotated at 15° increments from the incidence beam angle. A multi-leaf collimator (MLC) with four field sizes of 0.5 × 0.5, 1 × 1, 2 × 2, and 3 × 3 cm 2 , and four couch angles from 0°, 30°, 60°, and 90° (coplanar and non-coplanar) were adopted. The angular dependence response (AR) was defined as the ratio of the detector response at a given irradiation gantry angle normalized to the detector response at 0°. The maximum AR differences were calculated between the maximum and minimum AR values for each detector, field size, energy, and couch angle., Results: The maximum AR difference for the coplanar beam was within 3.3% for all conditions, excluding the maximum AR differences in 0.5 × 0.5 cm 2 field for CC01 and RAZOR. The maximum AR difference for non-coplanar beams was within 2.5% for fields larger than 1 × 1 cm 2 , excluding the maximum AR differences for RAZOR Nano, SFD, and microSilicon. The Pinpoint 3D demonstrated stable AR tendencies compared to other detectors. The maximum difference was within 2.0%, except for the 0.5 × 0.5 cm 2 field and couch angle at 90°. The tendencies of AR values for each detector were similar when using different energies., Conclusion: This study clarified the inherent angular dependence of seven detectors that were suitable for small-field dosimetry. The Pinpoint 3D chamber had the smallest angular dependence of all detectors for the coplanar and non-coplanar beams. The findings of this study can contribute to the calculation of the AR correction factor, and it may be possible to adapt detectors with a large angular dependence on coplanar and non-coplanar beams. However, note that the gantry sag and detector-specific uncertainties increase as the field size decreases., (© 2022 American Association of Physicists in Medicine.)

In this study, an independent dose verification plugin (DVP) using the Eclipse Scripting Application Programming Interface (ESAPI) for brachytherapy was developed. The DVP was based on the general 2D formalism reported in AAPM-TG43U1. The coordinate and orientation of each source position were extracted from the translation matrix acquired from the treatment planning system (TPS), and the distance between the source and verification point (r) was calculated. Moreover, the angles subtended by the center-tip and tip-tip of the hypothetical line source with respect to the verification point (θ and β) were calculated. With r, θ, β and the active length of the source acquired from the TPS, the geometry function was calculated. As the TPS calculated the radial dose function, g(r), and 2D anisotropy function, F(r,θ), by interpolating and extrapolating the corresponding table stored in the TPS, the DVP calculated g(r) and F(r,θ) independently from equations fitted with the Monte Carlo data. The relative deviation of the fitted g(r) and F(r,θ) for the GammaMed Plus HDR 192Ir source was 0.5% and 0.9%, respectively. The acceptance range of the relative dose difference was set to ±1.03% based on the relative deviation between the fitted functions and Monte Carlo data, and the linear error propagation law. For 64 verification points from sixteen plans, the mean of absolute values of the relative dose difference was 0.19%. The standard deviation (SD) of the relative dose difference was 0.17%. The DVP maximizes efficiency and minimizes human error for the brachytherapy plan check., (© The Author(s) 2022. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.)

Purpose: To quantify dose delivery errors for high-dose-rate image-guided brachytherapy (HDR-IGBT) using an independent end-to-end dose delivery quality assurance test at multiple institutions. The novelty of our study is that this is the first multi-institutional end-to-end dose delivery study in the world., Materials and Methods: The postal audit used a polymer gel dosimeter in a cylindrical acrylic container for the afterloading system. Image acquisition using computed tomography, treatment planning, and irradiation were performed at each institution. Dose distribution comparison between the plan and gel measurement was performed. The percentage of pixels satisfying the absolute-dose gamma criterion was reviewed., Results: Thirty-five institutions participated in this study. The dose uncertainty was 3.6% ± 2.3% (mean ± 1.96σ). The geometric uncertainty with a coverage factor of k = 2 was 3.5 mm. The tolerance level was set to the gamma passing rate of 95% with the agreement criterion of 5% (global)/3 mm, which was determined from the uncertainty estimation. The percentage of pixels satisfying the gamma criterion was 90.4% ± 32.2% (mean ± 1.96σ). Sixty-six percent (23/35) of the institutions passed the verification. Of the institutions that failed the verification, 75% (9/12) had incorrect inputs of the offset between the catheter tip and indexer length in treatment planning and 17% (2/12) had incorrect catheter reconstruction in treatment planning., Conclusions: The methodology should be useful for comprehensively checking the accuracy of HDR-IGBT dose delivery and credentialing clinical studies. The results of our study highlight the high risk of large source positional errors while delivering dose for HDR-IGBT in clinical practices., Competing Interests: Declaration of interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

The information of definitive radiotherapy for a pregnant woman with malignancy was limited; however, it was reported to be potentially feasible with minimal risks. We performed definitive chemoradiotherapy for a pregnant woman with locally advanced cervical esophageal cancer. Feasibility of radiotherapy and safety of fetus were confirmed by the phantom study estimating fetal dose, and monitoring it in each radiotherapy session. The planned chemoradiotherapy completely eradicated esophageal cancer while preserving her laryngopharyngeal function. A female infant was delivered by cesarian section after planned chemoradiotherapy, and she grew without any apparent disorders 2 years after chemoradiotherapy. Chemoradiotherapy might be one of the treatment options for a pregnant woman with cervical esophageal cancer especially wishing the preservation of laryngopharyngeal function., Competing Interests: Conflict of interestThe authors declare that they have no conflict of interest., (© The Author(s) under exclusive licence to The Japan Society of Clinical Oncology 2022.)

Purpose: To evaluate the displacement of gross tumor volume (GTV) positions caused by intrafractional residual setup errors (RSEs) and to accumulate delivered dose distributions considering intrafraction RSEs in fractionated-stereotactic radiotherapy (f-SRT) with single isocenter volumetric modulated arc therapy (SI-VMAT) for multiple brain metastases., Methods: Overall, 72 consecutive patients who underwent f-SRT with SI-VMAT for multiple brain metastases were included. For all patients, 6D correction was performed using the ExacTrac X-ray (ETX) system. GTV displacement (ΔD) was calculated considering the intrafractional RSEs measured by the ETX system during irradiation. The correlation between ΔD and the distance from the isocenter to each GTV (d) was analyzed. Computed tomography (CT) images considering the intrafractional RSEs were generated for five patients with ΔD > 1 mm. The delivered dose distributions for all fractions were reconstructed on the corresponding CT, followed by their accumulation., Results: The 95th percentile of ΔD from 7,270 resultant center positions of 417 GTVs was 0.92 mm. No correlation was observed between ΔD and d. For 53 GTVs from five patients with ΔD > 1 mm, the difference of GTV D 99.5% and D 0.5% between the planned and accumulated values was -0.4 ± 2.5% and -1.0 ± 0.8%, respectively. There was no correlation between d and the difference of GTV D 99.5% and D 0.5% ., Conclusions: We found no significant difference in GTV D 99.5% and D 0.5% , despite the location of GTVs far from the isocenter. However, it should be noted that this result was because the intrafractional RSEs were reduced to a clinically acceptable level., (Copyright © 2022 Associazione Italiana di Fisica Medica e Sanitaria. Published by Elsevier Ltd. All rights reserved.)

In forensic investigations, it is crucial to detect a suspect's DNA from the available evidence. In an outdoor crime scene, the evidence may be mixed with the soil. However, soil is speculated to inhibit DNA extraction from forensic science samples. In the field of soil microbiology, it is necessary to extract DNA directly from soil to analyse its microbial composition. In this study, we investigated whether skim milk used in procedure of DNA extraction from soil samples could be applied to forensic science to enhance human DNA extraction efficiency from soil mixed with forensic evidence, such as blood, buccal cells, and skin cells. The use of additive reagents, skim milk and bovine serum albumin (BSA), are known to blocking reagent. In the selection of additive reagents experiment, about blood sample, using the skim milk and BSA were found to increase the DNA yield. Therefore, we observed extracted DNA yield from blood, buccal cells, and skin cells when skim milk and BSA were used as additive reagents. The DNA recovery rate was high across all samples upon addition of skim milk. However, in STR analysis, a non-specific peak was detected in the extracted DNA in the presence of skim milk, which was not detected in the presence of BSA, indicating its suitability in forensic analysis. Our study suggests that addition of BSA can efficiently aid the extraction of DNA from forensic evidence mixed with soil., Competing Interests: Declarations of interest None., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Rosai-Dorfman-Destombes disease (RDD) is a non-Langerhans cell histiocytosis characterized by the accumulation of histiocytes inside the lymph nodes or extranodally. The association between RDD and IgG4-related disease (IgG4-RD) is discussed. We herein report a case of RDD manifesting as acute tubulointerstitial nephritis mimicking IgG4-RD. The first renal biopsy showed severe tubulointerstitial nephritis with infiltration of S100-positive histiocytes and IgG4-positive plasma cells; storiform fibrosis and obliterative phlebitis were not confirmed. After prednisolone therapy, IgG4-positive cells and S100-positive histiocytes were decreased, but the IgG4/IgG ratio increased despite clinical improvement. These findings indicated extranodal RDD in the kidney presenting as tubulointerstitial nephritis.

To evaluate the reproducibility of dose-based radiomic (dosiomic) features between dose-calculation algorithms for lung stereotactic body radiation therapy (SBRT). We analyzed 105 patients with early-stage non-small cell lung cancer who underwent lung SBRT between March 2011 and December 2017. Radiation doses of 48, 60, and 70 Gy were prescribed to the isocenter in 4-8 fractions. Dose calculations were performed using X-ray voxel Monte Carlo (XVMC) on the iPlan radiation treatment planning system (RTPS). Thereafter, the radiation doses were recalculated using the Acuros XB (AXB) and analytical anisotropic algorithm (AAA) on the Eclipse RTPS while maintaining the XVMC-calculated monitor units and beam arrangements. A total of 6808 dosiomic features were extracted without preprocessing (112 shape, 144 first-order, and 600 texture features) or with wavelet filters to eight decompositions (1152 first-order and 4800 texture features). Features with absolute pairwise concordance correlation coefficients-|CC con |-values exceeding or equaling 0.85 were considered highly reproducible. Subgroup analyses were performed considering the wavelet filters and prescribed doses. The numbers of highly reproducible first-order and texture features were 34.8%, 26.9%, and 31.0% for the XVMC-AXB, XVMC-AAA, and AXB-AAA pairs, respectively. The maximum difference between the mean |CC con | values was 0.70 and 0.11 for the subgroup analyses of wavelet filters and prescribed dose, respectively. The application of wavelet filter-based dosiomic analyses may be limited when using different types of dose-calculation algorithms for lung SBRT., (© 2022. Japanese Society of Radiological Technology and Japan Society of Medical Physics.)

Dialysis patients have an increased risk of coronavirus disease 2019 (COVID-19)-related mortality. Acute heart failure is a frequent, lethal complication of COVID-19, and it is a risk factor for mortality in hemodialysis patients. Therefore, it is crucial to rapidly distinguish heart failure from COVID-19 pneumonia. Here, we report a case of two episodes of acute dyspnea that were induced by COVID-19 in a peritoneal dialysis (PD) patient. The first episode of acute dyspnea was an exacerbation of heart failure caused by COVID-19 when the patient had a volume overload status due to a peritoneal dialysis catheter malfunction. Heart failure induced by a catheter malfunction was due to omental wrapping, and it was treated with ultrafiltration by hemodialysis and mini-laparotomy. The patient's acute dyspnea was immediately resolved. The second episode of acute dyspnea was caused by COVID-19 pneumonia, which occurred 1 week after the first episode. This case suggests the importance of identifying heart failure and beginning adequate treatment, in COVID-19 patients with PD., (© 2021. Japanese Society of Nephrology.)

Details of Young Researchers' Association of Medical Physics (YRAMP) was introduced. In addition, several questionnaire surveys on medical physics education (MPE) or medical physicist training system (MPTS) in Japan have been conducted, none have targeted the current status and issues of MPE and MPTS. The purpose of this study was to investigate those from the perspective of researchers and students under 35-year-old (y.o.). The questionnaire survey was conducted between 14th September to 14th October 2021, for 112 members of the Young Researchers' Association of Medical Physics via Google Forms. The questionnaire was in two parts: MPE (Part1) and MPTS (Part2). Three subparts were constructed in Part1: Classroom lecture, Clinical training, Education course accredited by Japanese Board of Medical Physicist Qualification. Out of a total of 126 questions, 38 were mandatory to be answered. No personal information was collected. Ninety-three members (83.0%) were answered. The age structure of the respondents was as follows: 18-21, 22-26, 27-30, and 31-35 y.o.=5.4%, 36.6%, 39.8%, and 18.2%. Of the respondents, 74.2% and 11.8% answered that they first heard of "medical physics" or "medical physicist" when they were undergraduate students and in high school or younger, respectively. In Classroom lecture, 61.3%, 17.2%, and 21.5% of the respondents answered that they were "satisfied" or "moderately satisfied", "dissatisfied" or "moderately dissatisfied", and "Not sure" with the current MPE, respectively. In Clinical training, Education course, and MPTS, 58.1%, 21.5%, and 20.4% of the respondents answered that they were "satisfied" or "moderately satisfied", "dissatisfied" or "moderately dissatisfied", and "Not sure", respectively. In both MPE and MPTS, approximately 88% and 51% of the respondents answered that "holding lectures and study sessions for high school and undergraduate students" and "utilizing YouTube" would be useful in promoting MPE and MPTS in Japan, respectively. The results of the questionnaire survey will provide useful data for MPE and MPTS in Japan.

Background: This study aimed to (1) develop a fully residual deep convolutional neural network (CNN)-based segmentation software for computed tomography image segmentation of the male pelvic region and (2) demonstrate its efficiency in the male pelvic region., Methods: A total of 470 prostate cancer patients who had undergone intensity-modulated radiotherapy or volumetric-modulated arc therapy were enrolled. Our model was based on FusionNet, a fully residual deep CNN developed to semantically segment biological images. To develop the CNN-based segmentation software, 450 patients were randomly selected and separated into the training, validation and testing groups (270, 90, and 90 patients, respectively). In Experiment 1, to determine the optimal model, we first assessed the segmentation accuracy according to the size of the training dataset (90, 180, and 270 patients). In Experiment 2, the effect of varying the number of training labels on segmentation accuracy was evaluated. After determining the optimal model, in Experiment 3, the developed software was used on the remaining 20 datasets to assess the segmentation accuracy. The volumetric dice similarity coefficient (DSC) and the 95th-percentile Hausdorff distance (95%HD) were calculated to evaluate the segmentation accuracy for each organ in Experiment 3., Results: In Experiment 1, the median DSC for the prostate were 0.61 for dataset 1 (90 patients), 0.86 for dataset 2 (180 patients), and 0.86 for dataset 3 (270 patients), respectively. The median DSCs for all the organs increased significantly when the number of training cases increased from 90 to 180 but did not improve upon further increase from 180 to 270. The number of labels applied during training had a little effect on the DSCs in Experiment 2. The optimal model was built by 270 patients and four organs. In Experiment 3, the median of the DSC and the 95%HD values were 0.82 and 3.23 mm for prostate; 0.71 and 3.82 mm for seminal vesicles; 0.89 and 2.65 mm for the rectum; 0.95 and 4.18 mm for the bladder, respectively., Conclusions: We have developed a CNN-based segmentation software for the male pelvic region and demonstrated that the CNN-based segmentation software is efficient for the male pelvic region., (© 2021. The Author(s).)

Purpose: This study aimed to assess dosimetric indices of RapidPlan model-based plans for different energies (6, 8, 10, and 15 MV; 6- and 10-MV flattening filter-free), multileaf collimator (MLC) types (Millennium 120, High Definition 120, dual-layer MLC), and disease sites (head and neck, pancreatic, and rectal cancer) and compare these parameters with those of clinical plans., Methods: RapidPlan models in the Eclipse version 15.6 were used with the data of 28, 42, and 20 patients with head and neck, pancreatic, and rectal cancer, respectively. RapidPlan models of head and neck, pancreatic, and rectal cancer were created for TrueBeam STx (High Definition 120) with 6 MV, TrueBeam STx with 10-MV flattening filter-free, and Clinac iX (Millennium 120) with 15 MV, respectively. The models were used to create volumetric-modulated arc therapy plans for a 10-patient test dataset using all energy and MLC types at all disease sites. The Holm test was used to compare multiple dosimetric indices in different treatment machines and energy types., Results: The dosimetric indices for planning target volume and organs at risk in RapidPlan model-based plans were comparable to those in the clinical plan. Furthermore, no dose difference was observed among the RapidPlan models. The variability among RapidPlan models was consistent regardless of the treatment machines, MLC types, and energy., Conclusions: Dosimetric indices of RapidPlan model-based plans appear to be comparable to the ones based on clinical plans regardless of energies, MLC types, and disease sites. The results suggest that the RapidPlan model can generate treatment plans independent of the type of treatment machine., (© 2021 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.)

The reports of chemoradiotherapy for anal squamous cell carcinoma with Crohn's disease are few. Severe toxicity related to radiotherapy is concerned in patients with inflammatory bowel disease. We report a case of chemoradiotherapy for locally advanced fistula-related perianal squamous cell carcinoma in a patient with long-standing Crohn's disease which was controlled by a maintenance therapy. The patient completed standard chemoradiotherapy using intensity-modulated radiotherapy without severe toxicity, and achieved complete remission. Standard chemoradiotherapy using intensity-modulated radiotherapy may be feasible and effective treatment for this population when Crohn's disease is controlled., Competing Interests: Conflict of interestThe authors declare that they have no conflict of interest., (© The Japan Society of Clinical Oncology 2021.)

Background: We investigated the geometric and dosimetric impact of three-dimensional (3D) generative adversarial network (GAN)-based metal artifact reduction (MAR) algorithms on volumetric-modulated arc therapy (VMAT) and intensity-modulated proton therapy (IMPT) for the head and neck region, based on artifact-free computed tomography (CT) volumes with dental fillings., Methods: Thirteen metal-free CT volumes of the head and neck regions were obtained from The Cancer Imaging Archive. To simulate metal artifacts on CT volumes, we defined 3D regions of the teeth for pseudo-dental fillings from the metal-free CT volumes. HU values of 4000 HU were assigned to the selected teeth region of interest. Two different CT volumes, one with four (m4) and the other with eight (m8) pseudo-dental fillings, were generated for each case. These CT volumes were used as the Reference. CT volumes with metal artifacts were then generated from the Reference CT volumes (Artifacts). On the Artifacts CT volumes, metal artifacts were manually corrected for using the water density override method with a value of 1.0 g/cm 3 (Water). By contrast, the CT volumes with reduced metal artifacts using 3D GAN model extension of CycleGAN were also generated (GAN-MAR). The structural similarity (SSIM) index within the planning target volume was calculated as quantitative error metric between the Reference CT volumes and the other volumes. After creating VMAT and IMPT plans on the Reference CT volumes, the reference plans were recalculated for the remaining CT volumes., Results: The time required to generate a single GAN-MAR CT volume was approximately 30 s. The median SSIMs were lower in the m8 group than those in the m4 group, and ANOVA showed a significant difference in the SSIM for the m8 group (p < 0.05). Although the median differences in D 98% , D 50% and D 2% were larger in the m8 group than the m4 group, those from the reference plans were within 3% for VMAT and 1% for IMPT., Conclusions: The GAN-MAR CT volumes generated in a short time were closer to the Reference CT volumes than the Water and Artifacts CT volumes. The observed dosimetric differences compared to the reference plan were clinically acceptable.

Purpose: To introduce the concept of statistical shape model (SSM)-based planning organ-at-risk volume (sPRV) for pancreatic cancer patients., Methods: A total of 120 pancreatic cancer patients were enrolled in this study. After correcting inter-patient variations in the centroid position of the planning target volume (PTV), four different SSMs were constructed by registering a deformable template model to an individual model for the stomach and duodenum. The sPRV, which focused on the following different components of the inter-patient variations, was then created: Scenario A: shape, rotational angle, volume, and centroid position; Scenario B: shape, rotational angle, and volume; Scenario C: shape and rotational angle; and Scenario D: shape. The conventional PRV (cPRV) was created by adding an isotropic margin R (3-15 mm) to the mean shape model. The corresponding sPRV was created from the SSM until the volume difference between the cPRV and sPRV was less than 1%. Thereafter, we computed the overlapping volume between the PTV and cPRV (OL c ) or sPRV (OL s ) in each patient. OL s being larger than OL c implies that the local shape variations in the corresponding OAR close to the PTV were large. Therefore, OL s /OL c was calculated in each patient for each R-value, and the median value of OL s /OL c was regarded as a surrogate for plan quality for each R-value., Results: For R = 3 and 5 mm, OL s /OL c exceeded 1 for the stomach and duodenum in all scenarios, with a maximum OL s /OL c of 1.21. This indicates that smaller isotropic margins did not sufficiently account for the local shape changes close to the PTV., Conclusions: Our results indicated that, in contrast to conventional PRV, SSM-based PRVs, which account for local shape changes, would result in better dose sparing for the stomach and duodenum in pancreatic cancer patients.

Purpose: To evaluate intrafractional head motion (IFM) in patients who underwent intracranial stereotactic radiosurgery with the ExacTrac X-ray system (ETX) and a frameless mask., Methods: A total of 143 patients who completed a pre-treatment examination for IFM were eligible for this study. The frameless mask type B R408 (Klarity Medical & Equipment Co., Ltd., Guangzhou, China), which covers the back of the head, and the entire face, was used for patient immobilization. After the initial 6D correction and first X-ray verification (IFM 1 ), X-ray verification was performed every 3 min for a duration of 15 min. The IFM p (2 ≤ p ≤ 6) was calculated as the positional difference from IFM 1 . In addition, the inter-phase IFM (IP-IFM) and IFM m were calculated. The IP-IFM was defined as |IFM p  - IFM p -1 |, and IFM m as the difference between the values after all patients were asked to move their heads intentionally with the frameless mask on., Results: Both translational IFM p and IP-IFM exceeded 1 mm for a single patient, whereas, for all patients, the translational IFM m values were kept to within 1 mm in all directions. The proportions of the rotational IFM p , IP-IFM, and IFM m values within 0.5° were greater than 94.4%, 98.6%, and 90.2% for all of the rotational axes, respectively., Conclusions: A frameless mask achieved highly accurate patient positioning in combination with ETX and a 6°-of-freedom robotic couch; however, a deviation over 1 mm and 0.5° was observed with low frequency. Therefore, X-ray verification and correction are required during treatment., (Copyright © 2021 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

Objective: To quantify and correct megavoltage (MV) scattered X-rays (MV-scatter) on an image acquired using a linac-mounted kilovoltage (kV) imaging subsystem., Methods and Materials: A linac-mounted flat-panel detector (FPD) was used to acquire an image containing MV-scatter by activating the FPD only during MV beam irradiation. 6-, 10-, and 15 MV with a flattening-filter (FF; 6X-FF, 10X-FF, 15X-FF), and 6- and 10 MV without an FF (6X-FFF, 10X-FFF) were used. The maps were acquired by changing one of the irradiation parameters while the others remained fixed. The mean pixel values of the MV-scatter were normalized to the 6X-FF reference condition (MV-scatter value). An MV-scatter database was constructed using these values. An MV-scatter correction experiment with one full arc image acquisition and two square field sizes (FSs) was conducted. Measurement- and estimation-based corrections were performed using the database. The image contrast was calculated at each angle., Results: The MV-scatter increased with a larger FS and dose rate. The MV-scatter value factor varied substantially depending on the FPD position or collimator rotation. The median relative error ranges of the contrast for the image without, and with the measurement- and estimation-based correction were -10.9 to -2.9, and -1.5 to 4.8 and -7.4 to 2.6, respectively, for an FS of 10.0 × 10.0 cm 2 ., Conclusions: The MV-scatter was strongly dependent on the FS, dose rate, and FPD position. The MV-scatter correction improved the image contrast., Advances in Knowledge: The MV-scatters on the TrueBeam linac kV imaging subsystem were quantified with various MV beam parameters, and strongly depended on the fieldsize, dose rate, and flat panel detector position. The MV-scatter correction using the constructed database improved the image quality., (© 2020 The Authors. Published by the British Institute of Radiology.)

Purpose: The purpose of this study was to predict and classify the gamma passing rate (GPR) value by using new features (3D dosiomics features and combined with plan and dosiomics features) together with a machine learning technique for volumetric modulated arc therapy (VMAT) treatment plans., Methods and Materials: A total of 888 patients who underwent VMAT were enrolled comprising 1255 treatment plans. Further, 24 plan complexity features and 851 dosiomics features were extracted from the treatment plans. The dataset was randomly split into a training/validation (80%) and test (20%) dataset. The three models for prediction and classification using XGBoost were as follows: (i) plan complexity features-based prediction method (plan model); (ii) 3D dosiomics feature-based prediction model (dosiomics model); (iii) a combination of both the previous models (hybrid model). The prediction performance was evaluated by calculating the mean absolute error (MAE) and the correlation coefficient (CC) between the predicted and measured GPRs. The classification performance was evaluated by calculating the area under curve (AUC) and sensitivity., Results: MAE and CC at γ2%/2 mm in the test dataset were 4.6% and 0.58, 4.3% and 0.61, and 4.2% and 0.63 for the plan model, dosiomics model, and hybrid model, respectively. AUC and sensitivity at γ2%/2 mm in test dataset were 0.73 and 0.70, 0.81 and 0.90, and 0.83 and 0.90 for the plan model, dosiomics model, and hybrid model, respectively., Conclusions: A combination of both plan and dosiomics features with machine learning technique can improve the prediction and classification performance for GPR., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Purpose: To validate the clinical applicability of knowledge-based (KB) planning in single-isocenter volumetric-modulated arc therapy (VMAT) for multiple brain metastases using the k-fold cross-validation (CV) method., Methods: This study comprised 60 consecutive patients with multiple brain metastases treated with single-isocenter VMAT (28 Gy in five fractions). The patients were divided randomly into five groups (Groups 1-5). The data of Groups 1-4 were used as the training and validation dataset and those of Group 5 were used as the testing dataset. Four KB models were created from three of the training and validation datasets and then applied to the remaining Groups as the fourfold CV phase. As the testing phase, the final KB model was applied to Group 5 and the dose distributions were calculated with a single optimization process. The dose-volume indices (DVIs), modified Ian Paddick Conformity Index (mIPCI), modulation complexity scores for VMAT plans (MCSv), and the total number of monitor units (MUs) of the final KB plan were compared to those of the clinical plan (CL) using a paired Wilcoxon signed-rank test., Results: In the fourfold CV phase, no significant differences were observed in the DVIs among the four KB plans (KBPs). In the testing phase, the final KB plan was statistically equivalent to the CL, except for planning target volumes (PTVs) D 2% and D 50% . The differences between the CL and KBP in terms of the PTV D 99.5% , normal brain, and D max to all organs at risk (OARs) were not significant. The KBP achieved a lower total number of MUs and higher MCSv than the CL with no significant difference., Conclusions: We demonstrated that a KB model in a single-isocenter VMAT for multiple brain metastases was equivalent in dose distribution, MCSv, and total number of MUs to a CL with a single optimization., (© 2020 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.)

Purpose: To predict local recurrence (LR) and distant metastasis (DM) in early stage non-small cell lung cancer (NSCLC) patients after stereotactic body radiotherapy (SBRT) in multiple institutions using breath-hold computed tomography (CT)-based radiomic features with random survival forest., Methods: A total of 573 primary early stage NSCLC patients who underwent SBRT between January 2006 and March 2016 and met the eligibility criteria were included in this study. Patients were divided into two datasets: training (464 patients in 10 institutions) and test (109 patients in one institution) datasets. A total of 944 radiomic features were extracted from manually segmented gross tumor volumes (GTVs). Feature selection was performed by analyzing inter-segmentation reproducibility, GTV correlation, and inter-feature redundancy. Nine clinical factors, including histology and GTV size, were also used. Three prognostic models (clinical, radiomic, and combined) for LR and DM were constructed using random survival forest (RSF) to deal with total death as a competing risk in the training dataset. Robust models with optimal hyper-parameters were determined using fivefold cross-validation. The patients were dichotomized into two groups based on the median value of the patient-specific risk scores (high- and low-risk score groups). Gray's test was used to evaluate the statistical significance between the two risk score groups. The prognostic power was evaluated by the concordance index with the 95% confidence intervals (CI) via bootstrapping (2000 iterations)., Results: The concordance indices at 3 yr of clinical, radiomic, and combined models for LR were 0.57 [CI: 0.39-0.75], 0.55 [CI: 0.38-0.73], and 0.61 [CI: 0.43-0.78], respectively, whereas those for DM were 0.59 [CI: 0.54-0.79], 0.67 [CI: 0.54-0.79], and 0.68 [CI: 0.55-0.81], respectively, in the test dataset. The combined DM model significantly discriminated its cumulative incidence between high- and low-risk score groups (P < 0.05). The variable importance of RSF in the combined model for DM indicated that two radiomic features were more important than other clinical factors. The feature maps generated on the basis of the most important radiomic feature had visual difference between high- and low-risk score groups., Conclusions: The radiomics approach with RSF for competing risks using breath-hold CT-based radiomic features might predict DM in early stage NSCLC patients who underwent SBRT although that may not have potential to predict LR., (© 2020 American Association of Physicists in Medicine.)

This study aimed to investigate the feasibility of independent calculation-based verification of volumetric-modulated arc therapy (VMAT)-stereotactic body radiotherapy (SBRT) for patients with lung cancer using a secondary treatment planning system (sTPS). In all, 50 patients with lung cancer who underwent VMAT-SBRT between April 2018 and May 2019 were included in this study. VMAT-SBRT plans were devised using the Collapsed-Cone Convolution in RayStation (primary TPS: pTPS). DICOM files were transferred to Eclipse software (sTPS), which utilized the Eclipse software, and the dose distribution was then recalculated using Acuros XB. For the verification of dose distribution in homogeneous phantoms, the differences among pTPS, sTPS, and measurements were evaluated using passing rates of a dose difference of 5% (DD5%) and gamma index of 3%/2 mm (γ3%/2 mm). The ArcCHECK cylindrical diode array was used for measurements. For independent verification of dose-volume parameters per the patient's geometry, dose-volume indices for the planning target volume (PTV) including D 95% and the isocenter dose were evaluated. The mean differences (± standard deviations) between the pTPS and sTPS were then calculated. The gamma passing rates of DD5% and γ3%/2 mm criteria were 99.2 ± 2.4% and 98.6 ± 3.2% for pTPS vs. sTPS, 92.9 ± 4.0% and 94.1 ± 3.3% for pTPS vs. measurement, and 93.0 ± 4.4% and 94.3 ± 4.1% for sTPS vs. measurement, respectively. The differences between pTPS and sTPS for the PTVs of D 95% and the isocenter dose were -3.1 ± 2.0% and -2.3 ± 1.8%, respectively. Our investigation of VMAT-SBRT plans for lung cancer revealed that independent calculation-based verification is a time-efficient method for patient-specific quality assurance., (© 2020 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.)

The number of patients with head and neck squamous cell carcinoma (HNC) with mediastinal involvement is small, and appropriate treatment techniques have not been widely discussed. This study aimed to compare the efficacy of radiotherapy planning techniques in reducing lung irradiation while retaining target coverage. Among all HNC patients with mediastinal involvement who underwent radiotherapy between 2007 and 2014 at our hospital, seven consecutive patients were included in this study. Four different treatment plans were generated for each patient as follows: seven-field intensity-modulated radiation therapy (IMRT), modified IMRT in which the lateral beams avoided the lungs, three-full-arc volumetric-modulated arc therapy (VMAT), and VMAT with lung avoidance. We compared the outcomes of IMRT and VMAT plans using the paired t-test. After modifications were made to avoid lung irradiation, IMRT values for V 5Gy and V 20Gy decreased from 713.2 to 503.6 cm 3 (p = 0.011) and from 338.8 cm 3 to 267.0 cm 3 (p = 0.058), respectively. In the case of VMAT, lung V 5Gy and V 20Gy values decreased from 754.8 to 601.0 cm 3 (p = 0.004) and from 328.5 to 255.7 cm 3 (p = 0.020), respectively. Other factors did not significantly differ between the plans. In both IMRT and VMAT planning, lung doses were significantly reduced following the modification of the beams that cross the lungs with target coverage maintenance.

Purpose: To compare radiomic features extracted from diagnostic computed tomography (CT) images with and without contrast enhancement in delayed phase for non-small cell lung cancer (NSCLC) patients., Methods: Diagnostic CT images from 269 tumors [non-contrast CT, 188 (dataset NE); contrast-enhanced CT, 81 (dataset CE)] were enrolled in this study. Eighteen first-order and seventy-five texture features were extracted by setting five bin width levels for CT values. Reproducible features were selected by the intraclass correlation coefficient (ICC). Radiomic features were compared between datasets NE and CE. Subgroup analyses were performed based on the CT acquisition period, exposure value, and patient characteristics., Results: Eighty features were considered reproducible (0.5 ≤ ICC). Twelve of the sixteen first-order features, independent of the bin width levels, were statistically different between datasets NE and CE (p < 0.05), and the p-values of two first-order features depending on the bin width levels were reduced with narrower bin widths. Sixteen out of sixty-two features showed a significant difference, regardless of the bin width (p < 0.05). There were significant differences between datasets NE and CE with older age, lighter body weight, better performance status, being a smoker, larger gross tumor volume, and tumor location at central region., Conclusions: Contrast enhancement in the delayed phase of CT images for NSCLC patients affected some of the radiomic features and the variability of radiomic features due to contrast uptake may depend largely on the patient characteristics., (Copyright © 2019 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)