Objective To realize independent 3D dose calculation for intensity-modulated radiotherapy (IMRT) by building a two-source beam model of medical linear accelerator combined with a collapsed-cone convolution/superposition (CCCS) algorithm.Methods Two-source beam models of medical linear accelerators (Varian and Elekta) were built to calculate the 3D dose distributions using the CCCS algorithm.Scp,percent depth dose,and off-axis dose distribution were compared with the scanning data of ion chamber to confirm the calculation model.Twelve intensity-modulated treatment plans from each accelerator (a total of 24 plans) were selected for comparison.The calculation results of treatment planning system (TPS) were independently validated,and further compared with the measurement results of detector matrix.Results The dose deviations at the center of rectangle fields were lower than 1%,the deviation between doses at the same position in the field was not higher than 1%,and the positional deviation in the penumbra region was not higher than 1 mm.Gamma analysis based on 3%/3 mm standard was used to compare the results calculated by detectors and TPS.The pass rates were higher than 90%.Conclusions The independent 3D dose calculation for IMRT based on two-source beam model combined with CCCS algorithm has been successfully set up.The comparison between regular field and IMRT plan indicates that this method and calculation model can be used for independent 3D dose calculation of clinical plan.

Objective To establish a quantitative evaluation of quality control image for the onboard imaging system of medical linear accelerator.Methods An MV planar image of electronic portal imaging device (EPID) is acquired by both Elekta iViewGT and Varian aS1000,and a kV planar image and cone-beam computed tomography (CBCT) images of CBCT are acquired by both Elekta X-ray volume imaging (XVI) and Varian On-board Imager (OBI).Phantoms used here included Las Vegas,TOR18FG,and Catphan504.A series of image quality indicators were evaluated by analyzing the images mentioned above using a quantitative method.Results A quantitative value was calculated to represent the contrast resolution of EPID.A modulation transfer function (MTF) to describe spatial resolution and a quantitative value representing contrast resolution were calculated for the kV planar image.As for the CBCT system,a series of quantitative results of noise,uniformity,CT value accuracy,and contrast resolution and a MTF were calculated to represent the performance of CBCT system.Conclusions Based on common phantoms,a complete set of quantitative methods to evaluate the image quality of EPID and CBCT has been developed,which could provide a very good reference for the establishment of quality control system for image-guided radiotherapy.

Objective To establish a fast and accurate method for measurement of leaf position accuracy of dynamic multi-leaf collimator (MLC) using electronic portal imaging device (EPID) and EBT3 film dosimeter.Methods A Varian 6 MV accelerator was used with the gantry angle and the collimator angle fixed at zero degree.A total of 11 sliding window MLC fields were designed.Each field contained a group of strip fields with the same width.The width of a strip field ranged from 1 mm to 10 mm and the distance between two adjacent strip fields was 20 mm.The relationship between the width of the strip field (band width) and the full width at half maximum (FWHM) was calibrated using EPID and EBT3 as measurement tools.A field with a band width of 5 mm was designed in the same way and several MLC leaf deviations were made in different positions.EPID and EBT3 film dosimeter were used to analyze the leaf position accuracy.Results A good linear relationship between band width and FWHM was achieved when the band width was larger than 4 mm.The accuracy of band width,distance between peaks,and MLC leaf position were determined as ±0.2 mm,±0.1 mm,and ±0.1 mm by EPID and ±0.3 mm,±0.2 mm,and ± 0.2 mm by EBT3 film dosimeter,respectively.Conclusions This study provides a fast and accurate method for the measurement of MLC leaf position accuracy using EPID or EBT3 film dosimeter,which is helpful for quality assurance of MLC.

Objective:To analyze the risk factors of Intensive Care Unit-Acquired Weakness, and to develop and verify the model.Methods:A total of 247 patients admitted to ICU patients from November 2018 to October 2019 were selected, and risk factors between ICU acquired weakness group ( n=106) and non-ICU acquired weakness group( n=141)were compared using logistic regression for model construction.The Hosmer-Lemeshow test was used to verify the goodness of fit of the model. The area under the ROC curve was used to test the model to predict the effects. From November 2019 to May 2020, 106 patients were recruited for application of the model. Results:The incidence of ICU acquired weakness in this study was 42.91%(106/247), and 44.34%(47/106),the study finally included age ( OR=1.043) ,mechanical ventilation time ( OR=1.140) , APACHE II score ( OR=1.081) , blood sugar ( OR=1.117) , lactic acid( OR=1.459) ,and neuromuscular blockers ( OR=3.499) to construct the risk prediction. The model formula was P=1/1+exp (- Z) =1/1+exp (8.808-0.042×age -1.252×neuromuscular blockers-0.078×APACHE II score -0.110×blood sugar -0.378×lactic acid -0.131×mechanical ventilation time. The area under the ROC curve of this model was 0.896 (95% CI: 0.824-0.914) , the maximum value of the Youden index was 0.577, and the corresponding sensitivity was 0.754,the specificity was 0.823,the cutoff value was 0.503. The model verification results the sensibility of 70.2%, the specificity of 88.1%, and the accuracy of 80.2%. Conclusion:The predictic model of ICU acquired weakness couducted in this study has satisfactory prediction effect, which can provide a reference for clinical screening of high-risk patients.

Objective To develop an accurate 2D dose reconstruction model using electronic portal imaging device (EPID).2D dosimetric verifications of volumetric intensity-modulated arc therapy (VIMAT)were done using the model.And the results were compared to other dosimeters.Methods The EPID-based dose reconstruction model was using convolve,deconvolve and correction function.The dose profiles which were obtained by the ion chamber were used to determine the model parameters.A total of 12 VIMAT plans for the treatment of anatomical sites of various complexities were chosen.The results obtained from EPID were compared to other dosimeters and treatment planning system (TPS).The ion chamber was used to measure the central point absolute doses.Other dosimeters were used to measure the plane dose distributions.All dosimeters measured the dose at 10 cm depth.The results were analyzed using γevaluation method.Results Regarding absolute central point doses,the ion chamber results were within 1.5％ of the EPID results.For the comparison to Seven29 and Matrixx,the average γ pass rates with 2％and 2 mm criteria were 98.9％ and 99.8％ respectively.For the dose distributions measured by EPID and calculated by TPS,the γ pass rates with 3％ and 3 mm criteria were 99.9％.Conclusions The presented results which were obtained from the comparison of measured and calculated doses show the reliability of our EPID-based dose reconstruction model.With the model,EPID can be a reliable and fast tool for IMRT plan dosimetric verification.The model expanded to the 3D dosimetric verification in the uniform phantom will be considered as the next work.

BACKGROUNDTo ascertain the effect of chemotherapy combined with radiosurgery therapy on the brain metastasis of lung cancer.

METHODSTwenty-four non-small cell lung cancer patients with brain metastasis who received radiosurgery and chemotherapy were prospectively observed. Main parameters of treatment program included:(1)brain tumor size range from 1.9 to 26.2m³; (2)median iso-center numbers being 3 (1-7); (3)margin dose being 13.6-22.0 Gy. Chemotherapy regimen consisted of Teniposide (VM26), CCNU and carboplatin (CBP), with VM-26 100mg IV d1-3, CCNU 80mg po d1 and CBP 300mg/m² IV d1, repeated every 4 weeks for 2-4 cycles (CCNU used only in cycle 1 and 3).

RESULTS(1)Major neurological improvement rate was 87.0%; (2)Objective response rate of brain lesions was 58.3%; (3)Relapse rate of new lesions of the brain metastasis during 3-6 months after radiosurgical treatment was 70.8%; (4)Median survival duration was 10 months (range from 3 to 34 months); (5)l-year survival rate was 37.5%.

CONCLUSIONS(1)Chemotherapy combined with radiosurgery in the treatment of brain metastasis of non-small cell lung cancer might be an effective regimen with modest side effect; (2)Relapsing and new lesions in the brain can not be controlled with this treatment.

Objective To evaluate the efficacy of liraglutide in the treatment of Nonalcoholic Fatty Liver Disease(NAFLD).Methods Randomized controlled trials(RCTs)that evaluated the efficacy of liraglutide for NAFLD treatment were searched in multiple databases,including Pubmed,EMBASE,the Cochrane library,CNKI,Wanfang database and VIP.Literature identification and data extraction were based on the inclusion and exclusion criteria.RevMan 5.3 software was used for Meta-analysis.Results A total of 7 RCTs with 500 patients of NAFLD were included.Improved liver histology,or improved the level of alanine aminotransferase[WMD=-25.32,95％CI(-37.22,-13.41),P<0.01] and aspartate aminotransferase[WMD=-24.56,95％CI(-35.10,-14.03),P<0.01] were seen in 12-48 weeks liraglutide treatment.However,liraglutide could not decreased the level of serum cholesterol[WMD=-14.38,95％CI(-48.95,-20.20),P=0.42] and triglyceride[WMD=-15.55,95％CI(-36.20,-5.10),P=0.14].Conclusion liraglutide has the therapeutic effect of NAFLD.

Objective To investigate the clinical features and related risk factors of osteoporosis and osteoporotic fracture (OPF) in patients with rheumatic diseases (RD),and the fracture predictive values of fracture risk assessment tool fracture risk assessment (FRAX(R))for Han patients.Methods A total of 313 untreated RD patients were included.Each individual BMD was measured at lumbar spine and femoral neck with Dual-energy X-ray absorptionary.Ten-year probability of fracture (％) was calculated by fracture risk assessment tool FRAX(R) of Chinese model.Each individual previous fracture was confirmed by X-ray or CT examination.The associations between BMD,FRAX),previous fracture and age,bone mass index,nationality,erythrocyte sedimentation rate (ESR) and RD types were analyzed.T test or Wilcoxon test was used to compare the difference between groups for statistical analysis.Pearson/Spearman rank order and binary regression were used to analyze the correlations between variables of normal/non-normal and two classification distribution.Results ① The BMD of patients with untreated RD was significantly lower than that of control group (P=0.000).Individuals diagnosed with "osteopenia" in the RD group and control group were accounted for 39.3％ (123/313) and 15.8％ (47/296) respectively.Individuals diagnosed with "osteoporosis" in RD group and control group were accounted for 11.5％ (36/313) and 5.4％ (16/296) respectively.② The next 10-year probability of the hip (Z=-2.28,P=0.02) and major osteoporotic fracture (Z=-1.98,P=0.03) were higher than those of the control group,as well as the actual incidence of OPF (x2=25.11,P=0.00),the difference was statistically significant.③ 27.3％(18/66) and 55.0％(11/20) of the previous OPF patients in RD group and control group achieved the diagnostic criteria of "high risk" of hip fracture.And 12.1％ (8/66) and 35.0％ (7/20) achieved the "high risk" of major osteoporotic fracture.④ Patients with RA,SLE and pSS had significantly increased risk of fracture.Ten-year fracture risks were negatively related to advanced age,female gender and ESR.Conclusion Bone loss and increased fracture risk are prevalent in the early stage of untreated rheumatism patients.RA,SLE plays an important role in low bone mass.The FRAX China model may underestimate 10-year fracture probability of RD patients and controls.Further explore should be done to predict the FRAX China model on different areas and different RDs.

Objective To investigate the effects of glucagon like peptide 1 (GLP-1) agonist on myocardial hypoxia reoxygenation injury and its molecular mechanism. Methods H9C2 cells were divided into control group, hypoxia reoxygenation(H/ R) group, H/ R+GLP-1 group, and H/ R+GLP-1+phosphatidylinositol-3-kinase (PI3K) inhibitor LY294002 group. The cell proliferation activity, apoptosis rate, enzyme contents in the medium and the expressions of apoptosis-related genes were detected. After animal model of myocardial ischemia reperfusion injury (I/ R) was established and was treated with GLP-1 agonist and PI3K inhibitor, serum enzyme contents were detected. Results Hypoxia reoxygenation decreased the myocardial cell proliferation activity and phosphorylated-PI3K(p-PI3K), phosphorylated-protein kinase B (p-Akt), Bcl-2 protein expressions, increased the apoptotic cell number and creatine kinase ( CK), creatine kinase-MB ( CK-MB), lactate dehydrogenase ( LDH) contents in cell culture medium and Bax, caspase-3 protein expressions, which were ameliorated by GLP-1 ( all P < 0. 05). The myocardial cell proliferation activity and Bcl-2 protein expression of H/ R+GLP-1+LY294002 group were significantly lower than those of H/ R+GLP-1 group while the apoptotic cell number and CK, CK-MB, LDH contents in cell culture medium and Bax, Caspase-3 protein expressions were significantly higher (all P<0. 05). Serum CK, CK-MB, and LDH contents in rats of I/ R group were significantly higher than those in control group and I/ R+GLP-1 group. Serum CK, CK-MB, and LDH contents in rats of I/ R+GLP-1+LY294002 group were significantly higher than those in I/ R+GLP-1 group(all P < 0. 05). Conclusion GLP-1 agonist is able to protect the myocardial hypoxia reoxygenation injury via activating PI3K/ Akt signaling pathway.

Purpose: This study aimed to develop a nomogram for predicting pathologic complete response (pCR) after neoadjuvant chemoradiotherapy (CRT) in patients with esophageal squamous cell carcinoma (ESCC) by integrating hematological biomarkers and clinicopathological characteristics. Materials and Methods: Between 2003 and 2017, 306 ESCC patients who underwent neoadjuvant CRT followed by esophagectomy were analyzed. Besides clinicopathological factors, hematological parameters before, during, and after CRT were collected. Univariate and multivariate logistic regression analyses were performed to identify predictive factors for pCR. A nomogram model was built and internally validated. Results: Absolute lymphocyte count (ALC), lymphocyte to monocyte ratio, albumin, hemoglobin, white blood cell, neutrophil, and platelet count generally declined, whereas neutrophil to lymphocyte ratio (NLR) and platelet to lymphocyte ratio (PLR) increased significantly following neoadjuvant CRT. After surgery, 124 patients (40.5%) achieved a pCR. The pCR group demonstrated significantly more favorable survival than the non-pCR group. On multivariate analysis, significant factors associated with pCR included sex, chemotherapy regimen, post-CRT endoscopic finding, pre-CRT NLR, ALC nadir during CRT, and post-CRT PLR, which were incorporated into the prediction model. The nomogram indicated good accuracy in predicting pCR, with a C-index of 0.75 (95% confidence interval, 0.71 to 0.78). Conclusion Female, chemotherapy regimen of cisplatin/vinorelbine, negative post-CRT endoscopic finding, pre-CRT NLR (≤ 2.1), ALC nadir during CRT (> 0.35 ×109/L), and post-CRT PLR (≤ 83.0) were significantly associated with pCR in ESCC patients treated with neoadjuvant CRT. A nomogram incorporating hematological biomarkers to predict pCR was developed and internally validated, showing good predictive performance.