BACKGROUND: Bone marrow mesenchymal stem cells is the most promising tissue engineering seed cells because of their strong proliferation and passage ability, multi-directional differentiation potential, as well as no ethical problems and no rejection.OBJECTIVE: To review the recent advances in the directional differentiation of bone marrow mesenchymal stem cells induced by various conditions METHODS: The first author retrieved CNKI, PubMed, Wanfang databases for relevant articles published from January 2001 to September 2016. The keywords were bone marrow mesenchymal stem cells, BMSCs, directional differentiation in Chinese and English, respectively. Literature addressing experimental research and review were selected, and finally 48 articles were included.RESULTS AND CONCLUSION: Bone marrow mesenchymal stem cells can be induced in vitro to differentiate into chondrocytes, osteoblasts, adipocytes, and nerve cells by cytokines, chemical drugs, Chinese herbs and extracts, physical stimulation. To establish feasible induction conditions in vitro and improve cell induction efficiency is the basis for the clinical application of bone marrow mesenchymal stem cells.

Objective Knowledge?based radiotherapy ( KBRT ) can reduce the plan quality variability induced by different experiences between physicians and improve the quality of treatment plans. Methods The Varian Rapid Plan system was used to train a dose?volume histogram ( DVH) prediction model. The obtained model was preliminarily applied to semi?automatic design of the preoperative treatment plans for rectal cancer. Eighty high?quality volumetric modulated arc therapy plans were imported into the model training set of the Rapid Plan system. The structures of the plans were matched to the corresponding labels and codes as listed in the library. The training started after the verification of prescription. The residual plots,regression curves,geometric plots for organ at risk ( OAR) ,in?field DVH plots,and model training logs were examined. After removal of the mismatch, the original plans were assessed to rule out outliers and influential data points. More similar plans may be added for another round of training. Ten KBRT plans were designed using the final model and compared with the clinical plans. Results For the two major OARs,the femoral head and bladder,the average goodness of fit of the principal component were 0?999 415/1.0 and 0?999 963/1.0 for the DVH model,and 0?999 651/1.0 and 0?999 945/1.0 for geometry?based expected dose model,respectively. In all the plans, 11 had Cook ’ s distance values exceeding the tolerance and 4 had studentized residual values exceeding the tolerance. The outliers were all kept in the training set to generalize the scope of the model. The 10 KBRT plans had significantly improved homogeneity indices for PGTV and PTV than the original plans (P=0?00,0?04).The 10 KBRT plans also had significantly reduced D50% to the femoral head and bladder as well as significantly reduced mean doses to the bladder than the original plans (P=0?042,0?000,0?005). Conclusions In this study,the Rapid Plan system is used to train a KBRT model for design of preoperative radiotherapy plans for rectal cancer. The results of preliminary application meet the clinical requirements.

Objective To investigate the dose distribution and radiation risk of Varian thoracic cone beam computed tomography (CBCT) with default parameters with reference to Monte Carlo simulation and International Commission on Radiological Protection (ICRP) report 110.Methods EGSnrc/BEAMnrc code was used to simulate the material, thickness, and geometry of the kV CBCT source (kVS) to establish the kVS model.A benchmarked MCSIM code was applied to calculate the dose distribution in the ICRP phantom after the scan with the standard thoracic parameters (110 kV, 20 mA, and 262 mAs), and the conversion coefficient of absolute dose was obtained in a spherical phantom following the TG-61 protocol.The results of Monte Carlo simulation were validated by PDD and Profile in a water phantom and the measurement of the absolute dose in the computed tomography dose index (CTDI) phantom and Alderson phantom.The models including BEIR VⅡ were used to evaluate the radiation risks.Results With reference to the criterion of 3%/1 mm, the uncertainties of PDD and Profile were less than 2%.The difference between the measured and calculated values was<2.9% in the CTDI phantom and ≤0.05 cGy in the Alderson phantom.In the ICRP110 phantom, the doses to the left lung, right lung, left breast, right breast, heart, thyroid, trachea, cancellous bone, and cortical bone were 1.28, 1.39, 1.74, 1.80, 1.46, 0.48, 0.88, 0.85, and 1.84 cGy, respectively.The relative risks of ischemic heart disease, breast cancer, lung cancer, thyroid cancer, and tracheal cancer in a standard scan were1.001 , 1.009, 1.019, 1.000, and 1.008, respectively. Conclusions The accumulated dose and long-term risks of CBCT during image-guided thoracic radiotherapy cannot be neglected and should be effectively controlled.

ObjectiveTo investigate the accuracy of automated breast volume scanning (ABVS) for the measurement of breast tumor size.MethodsSixty-two breast tumors in 59 patients were included in this study and were examined using conventional ultrasound and ABVS to measure the maximal diameters of the tumors. And the measurement results were compared with the pathological maximal diameters.Results There were 21 malignant and 41 benign tumors according to histopathological evaluation. There were no signifi cant differences between the maximal diameters on ABVS and on pathological measurements for both benign tumors and malignant tumors (Z=1.761, 0.262,P=0.078, 0.794). However, for malignant tumors, the maximal diameters on conventional ultrasound were significantly smaller than those on pathological measurements (Z=3.743,P=0.000). For benign tumors, the maximal diameters on conventional ultrasound were similar with those on pathological measurements (Z=1.935,P=0.053). The measurement values of conventional ultrasound and ABVS were both positively correlated with those on pathological values (r=0.935, 0.964,r=0.870, 0.964). And the correlation coeffi cients between ABVS and pathological measurement values were higher than those between conventional ultrasound and pathological measurement values for both benign and malignant tumors. ConclusionABVS can assess the size of breast tumor more accurately than conventional ultrasound, especially for the malignant tumors.

Objective To compare the performances of four commercially available LINAC daily QA instruments.Methods The dosimetric stability of a LINAC including central axis output,flatness and symmetry were verified and fine-tuned using a 3-dimensional water phantom,dosimeters and ionization chambers.The baseline of the four instruments including LINA-C,QUICK-C,BEAM-C and QA3 were set thereafter.Daily measurements of LINAC were conducted with these instruments respectively and the results were compared.Arbitrary errors (CAX and SYM) beyond TG-142 tolerances were introduced to the LINAC to test the sensibilities of each instrument in detecting these changes.Results Relative to the baseline that were measured by the 3-dimensional water phantom and dosimeters,the results monitored by the four instruments were comparable.The maximum disparities of the CAX,FLAT,and SYM were 0.5％ (LINA-C),-0.45％ (QUICK-C),and 0.5％ (BEAM-C),respectively.All checkers detected the known errors successfully.Conclusions The stabilities of all the four evaluated instruments met the requirements of daily QA for LINAC.LINA-C verifies CAX only.QUICKE-C,BEAM-C and QA3 can be used to perform all the daily QA protocols as suggested by AAPM TG 142 report.They also provide unique additional functions.The setup of baseline determines if the morning checkers could measure the LINAC dosimetric parameters correctly.When an error is alarmed by the morning checker,it is recommended to verify the performance of the instrument first rather than recalibrating the LINAC immediately.

Objective To evaluate the feasibility and dosimetric features of a volume modulated arc therapy (VMAT)-configured model in knowledge-based optimization of fixed-field dynamic intensitymodulated radiotherapy (IMRT) plans based on the Varian RapidPlan system.Methods ① A dose-volume histogram prediction model was trained with 81 qualified preoperative VMAT plans for rectal cancer and then statistically verified.② For clinically approved 10 IMRT plans with the same dose prescription,the above model was used to automatically generate new optimization parameters and dynamic muhileaf collimator (MLC) sequences with field geometry and beam energy unchanged.③ In order to rule out the disparities between different versions,a single algorithm was used to calculate the absolute doses of the original and new plans.④ Statistical analyses were performed on dosimetric parameters after comparable target dose coverage was achieved in the two plans by appropriate normalization.Results On the basis of similar target dose homogeneity and coverage,RapidPlan significantly reduced the doses to the urinary bladder (D50％ by 9.01 Gy,P =0.000;Dmean by 8.08 Gy,P =0.005) and the femoral head (D50％ by 4.20 Gy,P =0.000;Dmean by 3.84 Gy,P=0.005) but significantly elevated the mean total number of monitor units (1211±99 vs.771±79,P=0.000) and the number of fields with multiple MLC carriage groups.The knowledge-based semi-automated optimization caused a significantly larger number of high-dose hotspots but a similar D2％ (52.54 vs.52.71 Gy,P=0.239).Conclusions The VMAT model can be used for the knowledge-based semi-automated optimization of IMRT plans to enhance the efficiency and OAR protection.However,the resulting high-dose hotspots need further manual intervention.

Objective To explore the Monte Carlo calculation methods for the absolute dose calibration and output factor of 6 MV flattening-filter ( FF) and flattening-filter free ( FFF) photon beams based on TrueBeam accelerator .Methods The BEAMnrc code was used to model the LINAC head of FF and FFF modes.The BEAM_up covers the components from the target to the monitor chamber , and BEAM_down includes the structures beneath the chamber , the dose deposit to the monitor chamber contributed by the incidence electrons and scattered particles from the secondary collimators were calculated respectively .The incidence electron-induced dose at certain depths on the central axis were simulated by means of the DOSXYZnrc code .By means of dose calibration equation , the calibration factor for the standard field (10 cm ×10 cm) and the output factors for various fields (1 cm ×1 cm-40 cm ×40 cm) were computed respectively .Results For the 6 MV FF and FFF beams under the standard 10 cm ×10 cm field, 1 MU equals to 7.747 ×1013 ±3.099 ×1011 and 3.248 ×1013 ±1.624 ×1011 electrons to the target , respectively , which deposited 21.53 and 35.01 cGy to the monitor chamber of the virtual accelerator respectively .The difference between the simulated and calculated output factors were 0.72%±1.4%and 0.56%±0.78%for FF and FFF , respectively .Conclusions The model generated and measured output factors agree well , indicating the good accuracy of the dose calculation by the model , which would provides basis for further clinical dosimetric studies .

Objective: To investigate the effects of acetabular coverage on the initial stability of the cup during total hip arthroplasty in developmental dysplasia of hip. Methods: There were 50 fourth-generation synthetic hemi-pelvises. The different cup coverage rate (100% group, 70% group, 60% group, 50% group, 40% group) was created in pelvis with 10 specimens per group. The synthetic hemi-pelvis was fixed rigidly to a customized fixture which was placed on the testing table of the material testing machine. Pull-out and torque test were conducted by computer-control in torsion testing machine. Results: In the acetabular cup pull-out test, the average pull-out force for mode of failure in 100%, 70%, 60%, 50%, and 40% group was 1 560.4±438.7, 1 467.2±349.8, 1 137.8±427.4, 737.4±134.8, 506.6±119.0 N, respectively. The pull-out force was reduced gradually. The pull-out force in 100% group was significantly higher than that in 50% (P=0.004) and 40% (P=0.001) group. The pull-out force in 70% group was significantly higher than that in 50% group (P=0.002) and 40% group (P=0.000). The force in 40% group was significantly lower than that in 60% group (P=0.013) and 50% group (P=0.021). In the acetabular cup torque test, the average torque for mode of failure in 100%, 70%, 60%, 50%, and 40% group was 28.0±3.7, 17.0±2.2, 9.4±1.1, 7.6±1.1, 6.4±1.1 N·m, respectively. The torque was reduced gradually. The torque in 100% group was significantly higher than that in other groups (P<0.05). There was no significant difference between 50% and 40% group (P>0.05). The torque in other groups were similar (P>0.05). Conclusion The present biomechanical study showed that different acetabular cup coverage rate affected the initial stability of the cup. The highest initial stability was observed in the cup with a 100% of cup coverage rate. The cup could not obtain 100% coverage when with acetabular rim defect. We should try our best to make the cup coverage reach to 70%. The 70% coverage rate has sufficient initial stability to meet daily activities without increasing the cup loosening rate.

Objective To compare the application effects of percutaneous tracheotomy and the traditional tracheotomy for patients in ICU. Methods From February 2015 to June 2016,56 patients in ICU of the First Hospital of Ninghai County were selected in the research and randomly divided into two groups according to the digital table, with 28 cases in each group. The traditional group received traditional tracheotomy. The percutaneous group received the percutaneous tracheotomy. The surgical blood loss,operative time,incision length,scar area,incision healing time, mechanical ventilation time,survival rate and incision infection,subcutaneous emphysema,trachea collapse and other complications were compared between the two groups. Results The operative blood loss,operative time,incision length,scar area,incision healing time,mechanical ventilation time in percutaneous group were (3. 14 ± 0. 15) mL, (10. 02 ± 3. 53)min,(1. 52 ± 1. 52)cm,(1. 18 ± 0. 12)cm2 ,(3. 53 ± 0. 44)d,(5. 73 ± 1. 13)d,respectively,which in the control group were (7. 24 ± 1. 91)mL,(30. 98 ± 11. 72)min,(5. 26 ± 5. 26)cm,(5. 72 ± 1. 95)cm2 ,(7. 46 ± 1. 25)d,(5. 67 ± 1. 82) d,respectively,the blood loss,operative time,incision length,operation scar area,incision healing time between the two groups had statistically significant differences (t = 8. 635,8. 052,8. 155,8. 742,9. 251, all P < 0. 05). The survival rate of the two groups was 100. 0％ . The incidence rate of incision infection,subcutaneous emphysema,trachea collapse in the percutaneous group was 17. 86％ ,which was significantly lower than 64. 29％ in the traditional group,the difference was statistically significant(χ2 = 15. 014,P < 0. 05). Conclusion Percutaneous tracheotomy and the traditional tracheotomy have certain effect for patients in ICU,compared with traditional tracheotomy, percutaneous tracheotomy has less blood loss, less operation time, can reduce the complications, and can replace traditional tracheotomy for rescue and treatment for ICU patients.

Objective To analyze the clinical and pathological features of chronic hepatitis B (CHB) patients with hepatic steatosis.Methods Clinical and pathological data of 841 patients with CHB who underwent liver biopsy in Zhejiang Provincial People’s Hospital during September 2015 to September 2018 were retrospectively reviewed.One hundred and thirty five gender and age-matched pairs of steatosis and non-steatosis patients entered the analysis.Multivariable Logistic regression and rank sum test were used to analyze the clinical features and risk factors of hepatic steatosis in CHB patients .Spearman correlation test was used to analyze the correlation between hepatic steatosis and HBV DNA , hepatic inflammation and fibrosis status.Results Logistic regression analysis showed that overweight ／obesity ( χ2 ＝3.947, OR ＝1.436, 95%CI 1.005-2.051, P＜0.05) and hyperlipidemia (χ2 ＝4.277,OR＝1.803,95%CI 1.031-3.151, P＜0.05) were the risk factors for hepatic steatosis in CHB patients.There was no correlation of hepatic steatosis with serum HBeAg and HBV DNA levels (Z＝-1.762,r＝-0.011, both P＞0.05). However, hepatic steatosis was negatively correlated with inflammatory grade and fibrosis grade of the liver (r＝-0.146 and -0.192, both P＜0.05).Conclusions Overweight／obesity and hyperlipidemia are associated with steatosis in CHB patients.Hepatic steatosis may not aggravate the degree of liver inflammation and fibrosis in CHB patients.