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Purpose: Establishing the tolerance limits of patient‐specific quality assurance (PSQA) processes based on the gamma passing rate (GPR) by using normal statistical process control (SPC) methods involves certain problems. The aim of this study was threefold: (a) to show that the heuristic SPC method can replace the quantile method for establishing tolerance limits in PSQA processes and is more robust, (b) to introduce an iterative procedure of "Identify‐Eliminate‐Recalculate" for establishing the tolerance limits in PSQA processes with unknown states based on retrospective GPRs, and (c) to recommend a workflow to define tolerance limits based on actual clinical retrospective GPRs. Materials and Methods: A total of 1671 volumetric‐modulated arc therapy (VMAT) pretreatment plans were measured on four linear accelerators (linacs) and analyzed by treatment sites using the GPRs under the 2%/2 mm, 3%/2 mm, and 3%/3 mm criteria. Normality testing was performed using the Anderson‐Darling (AD) statistic and the optimal distributions of GPRs were determined using the Fitter Python package. The iterative "Identify‐Eliminate‐Recalculate" procedure was used to identify the PSQA outliers. The tolerance limits of the initial PSQAs, remaining PSQAs after elimination, and in‐control PSQAs after correction were calculated using the conventional Shewhart method, two transformation methods, three heuristic methods, and two quantile methods. The tolerance limits of PSQA processes with different states for the respective methods, linacs, and treatment sites were comprehensively compared and analyzed. Results: It was found that 75% of the initial PSQA processes and 63% of the in‐control processes were non‐normal (AD test, p < 0.05). The optimal distributions of GPRs for the initial and in‐control PSQAs varied with different linacs and treatment sites. In the implementation of the "Identify‐Eliminate‐Recalculate" procedure, the quantile methods could not identify the out‐of‐control PSQAs effectively due to the influence of outliers. The tolerance limits of the in‐control PSQAs, calculated using the quantile of optimal fitting distributions, represented the ground truth. The tolerance limits of the in‐control PSQAs and remaining PSQAs after elimination calculated using the heuristic methods were considerably close to the ground truth (the maximum average absolute deviations were 0.50 and 1.03%, respectively). Some transformation failures occurred under both transformation methods. For the in‐control PSQAs at 3%/2 mm gamma criteria, the maximum differences in the tolerance limits for four linacs and different treatment sites were 3.10 and 5.02%, respectively. Conclusions: The GPR distributions of PSQA processes vary with different linacs and treatment sites but most are skewed. In applying SPC methodologies to PSQA processes, heuristic methods are robust. For in‐control PSQA processes, the tolerance limits calculated by heuristic methods are in good agreement with the ground truth. For unknown PSQA processes, the tolerance limits calculated by the heuristic methods after the iterative "Identify‐Eliminate‐Recalculate" procedure are closest to the ground truth. Setting linac‐ and treatment site‐specific tolerance limits for PSQA processes is necessary for clinical applications. [ABSTRACT FROM AUTHOR]

Purpose: Applying statistical process control (SPC) to intensity‐modulated radiotherapy (IMRT)/volumetric modulated arc therapy (VMAT) patient‐specific quality assurance (PSQA) program was recommended by the American Association of Physics in Medicine Task Group 218 report, but a comprehensive analysis of PSQA processes with non‐normal distributions is lacking. This study investigates SPC and process capability analysis (PCA) methods for non‐normal IMRT/VMAT PSQA processes. Methods: 1119 VMAT PSQAs were performed on three beam‐matched linear accelerators (linacs), using gamma analysis. The Anderson–Darling statistic was used to test normality. The control charts for each PSQA process were obtained using three non‐normal‐based methods and compared with the conventional Shewhart method. The ability of each PSQA process to produce an output within the specification limit was measured using the Cpk index; in this study, the Cpk index was calculated using two transformation methods and compared with that calculated using the conventional method. The performances of the three linacs were assessed using SPC and PCA methods. Results: All three PSQA processes were non‐normal (P < 0.005). Compared to the non‐normal‐based SPC and PCA methods, the false alarm rates of the conventional method for linac1, linac2, and linac3 were 0.83%, 3.77%, and 4.95% respectively; the minimum overestimated Cpk values were 0.59, 0.87, and 1.49, respectively. The process capabilities of the three beam‐matched linacs were at different levels. Conclusion: For non‐normal VMAT PSQA processes, the conventional SPC and PCA methods increase the false alarm rates and overestimate process capabilities. Instead, non‐normal‐based SPC and PCA methods are more reliable and accurate in non‐normal PSQA processes. Statistical process control and PCA are useful tools for assessing the performance of beam‐matched linacs. [ABSTRACT FROM AUTHOR]

Background: The aim of this study is to assess the effect of home enteral nutrition (HEN) on the myelosuppression of patients with nasopharyngeal cancer (NPC) during the course of concurrent chemoradiotherapy (CCRT). Methods: A total of 18 outpatients with NPC administered oral nutritional supplementation intervention at home during the course of CCRT were designated as the HEN group, whereas 36 patients with NPC who had previously completed CCRT were retrospectively included as the control group. Patient Generated Subjective Global Assessment, body mass index (BMI), and blood test were evaluated prior to CCRT. During the course of CCRT, blood test was assessed every 2 weeks. Results: In male patients, hemoglobin (HB) and red blood cell were decreased (P < .05) in both HEN and control group after CCRT, whereas white blood cell (WBC) started to decrease since week 2 of CCRT in the control group but maintained in the HEN group which was significantly higher than the control (5.05 ± 1.29 vs 3.77 ± 1.5, P < .05). In female patients, HB and WBC were reduced in control group during CCRT, whereas these indicators also maintained in the HEN group. Surprisingly, all patients with lower BMI (<24 kg/m2) had a significant increase in platelet (PLT) after CCRT (200.78 ± 58.03 vs 253.00 ± 69.82, P < .05), while had steady HB and WBC values in the HEN group. At the end of CCRT, WBC and PLT of the HEN group were both higher than those in the control group (5.21 ± 1.07 vs 3.37 ± 1.52), (253.00 ± 69.82 vs 165.57 ± 59.56) (P < .05 for both). Our findings suggest that HEN is effective in preventing myelosuppression during CCRT for patients with NPC. Conclusion: Our findings suggest that HEN is effective in preventing myelosuppression during CCRT for patients with NPC. [ABSTRACT FROM AUTHOR]

Background Non-small cell lung cancer ( NSCLC) harboring kinase-domain mutations in epidermal growth factor receptors ( EGFR) has been observed to be sensitive to ionizing radiation ( IR). We explore Rad51-dependent homologous recombination ( HR) DNA repair in regulating radiosensitivity in two NSCLC cell lines with different EGFR mutation status. Methods NSCLC cell lines, wild-type EGFR A549 and mutant EGFR H820 with an in-frame deletion in exon 19 of EGFR (Δ E746- E750), were cultured. Radiosensitivity was estimated by colony forming assay. Rad51 expression was evaluated by quantitative real time-polymerase chain reaction and Western-blot. Lentiviral small hairpin ribonucleic acid- Rad51 and Δ E746- E750 deletion mutant EGFR were constructed and transfected into cells. Flowcytometry assay was used to analyze DNA double strand breaks, cell cycle alterations, and apoptosis. Results A549 had a higher survival factor ( SF)2 (0.66 vs. 0.44) and lower α/β value (4.07 vs. 9.01). Compared with the A549 cell, the H820 cell exhibited defective arrest in the S-phase, a higher rate of G2/M accumulation, early apoptosis, and residual γ- H2AX. Downregulated Rad51 expression decreased SF2 (0.42 vs. 0.31) and increased the α/β ratio (7.51 vs. 10.5), G2/M accumulation, early apoptosis, and γ- H2AX in two cell lines. H820 had a low IR-induced Rad51 expression and nuclear translocation. Exogenous expression of the Δ E746- E750 deletion mutant EGFR caused the A549 cell to become more radiosensitive. Conclusions An EGFR mutated NSCLC cell line is sensitive to IR , which is correlated with reduced IR-induced Rad51 expression and nuclear translocation. The signaling pathway of EGFR maintaining Rad51 protein levels maybe a novel lung cancer therapeutic target to overcome radioresistance. [ABSTRACT FROM AUTHOR]

Martian dust plays an important role in modulating climate. However, the effects of dust on polar CO2 ice caps, atmospheric circulation processes and the relationship between them are not yet clear. In this study, a Mars general circulation model (MarsWRF) was applied to investigate the impacts of the magnitude and timing of Martian dust storms on the spatiotemporal characteristics of polar CO2 ice caps and atmospheric circulation. The results show that dust can inhibit the sublimation of southern CO2 ice through the radiation effect. Under the "High Dust" scenario, the ice edge can extend up to 5° more equatorward than that under the "Standard" scenario around Ls = 220°. The extent of northern CO2 ice cap is hardly affected by dust because the impacts induced by dust mainly appear north of 80°N. By shifting the timing of maximum dust loading during the dust season, the "Early Dust" scenario inhibits the sublimation of the southern ice cap, while the "Late Dust" scenario accelerates the sublimation process. In addition, the variations in dust loading strength can lead to changes in three near‐surface wind belts, which are related to intensified Hardly circulation. The appearance of the warming vortex under the "Early Dust" scenario is delayed, and its intensity is 60 K lower than that observed in the "High Dust" and "Late Dust" scenarios. When dust loading increases, the northern CO2 condensation process in the Western Hemisphere accelerates, which is due to the increased pole‐to‐equator temperature gradient and the increased meridional wind speed. Plain Language Summary: Dust has a strong influence on the Martian climate. However, the dust effects on polar CO2 ice caps and wind fields have not yet been fully investigated. In this study, a numerical model that simulates the Martian climate was applied to investigate changes in the spatial and temporal patterns of CO2 ice caps and three‐dimensional wind fields. The results show that dust can inhibit the sublimation of southern CO2 ice by influencing the surface energy balance, while the coverage area of the northern CO2 ice cap is hardly affected by dust because the impacts induced by dust mainly appear north of 80°N. In terms of the timing of Martian dust storms, when a dust storm starts early (late), the sublimation of the southern ice cap is inhibited (accelerated). The appearance of the warming vortex will be delayed and its temperature will be 60 K lower than that in the general scenario if the dust storm starts early. When dust loading increases, the northern surface CO2 ice in the Western Hemisphere also increases, which is due to the increased pole‐to‐equator temperature gradient and increased meridional wind speed. Key Points: High dust loading decelerates the recession of southern CO2 ice cap, while the extent of northern CO2 ice cap is hardly affected by dustWhen Martian dust storm starts early, the appearance of the warming vortex is delayed and its intensity weakensThe increase in northern surface CO2 ice is induced by the increased polar‐equator temperature gradient and the increased meridional flow [ABSTRACT FROM AUTHOR]