Objective:To discuss the protective effect of velvet antler peptide(VAP)on the postmenopausal osteoporosis(PMOP)model rats,and to clarify its possible mechanism.Methods:A total of 60 twelve-week-old female SD rats were randomly divided into sham operation group,model group,alendronate sodium group(1 mg·kg 1·d-1 alendronate sodium administered via gavage),low dose of VAP group(100 mg·kg·d-1 VAP administered via gavage),medium dose of VAP group(200 mg·kg 1·d-1 VAP administered via gavage),and high dose of VAP group(300 mg·kg1·d-1 VAP administered via gavage),and there were 10 rats in each group.Except for the sham operation group,the rats in the other groups underwent bilateral ovariectomy to establish the PMOP rat models.Dual-energy X-ray absorptiometry was used to detect the femur bone mineral density(BMD)of the rats in various groups;enzyme-linked immunosorbent assay(ELISA)was used to detect the levels of serum calcium(Ca2+),serum phosphorus(P),bone alkaline phosphatase(BALP),and procollagen type Ⅰ N-terminal propeptide(PINP)of the rats in various groups;Kits were used to detect the activities of superoxide dismutase(SOD)and the levels of malondialdehyde(MDA)of the rats in various groups;HE staining was used to observe the pathomorphology of bone tissue of the rats in various groups;Western blotting method was used to detect the expression levels of phosphatidylinositol 3-kinase(PI3K),phosphorylated PI3K(p-PI3K),protein kinase B(AKT),and phosphorylated AKT(p-AKT)proteins in bone tissue of the rats in various groups.Results:Compared with sham operation group,the BMD in femur of the rats in model group was decreased(P＜0.01);compared with model group,the BMD in femur of the rats in alendronate sodium group,medium dose of VAP group,and high dose of VAP group was increased(P＜0.05 or P＜0.01).Compared with sham operation group,the levels of Ca2+,P,BALP,PINP,and SOD activity in serum of the rats in model group were decreased(P＜0.05 or P＜0.01),and the MDA level was increased(P＜0.01);compared with model group,the level of P in serum of the rats in medium dose of VAP group was increased(P＜0.01),and the levels of Ca2+,P,BALP,PINP and the activities of SOD in serum of the rats in alendronate sodium group and high dose of VAP group were increased(P＜0.05 or P＜0.01),and the level of MDA in serum was decreased(P＜0.05).The HE staining results showed that compared with sham operation group,the bone trabeculae in bone tissue of the rats in model group were thin and fractured,and the medullary cavity was enlarged;compared with model group,the bone trabeculae in bone tissue of the rats in alendronate sodium group,medium dose of VAP group,and high dose of VAP group were thick and tightly arranged,and had more osteocytes.The Western blotting results showed that compared with sham operation group,the ratios of p-PI3K/PI3K and p-AKT/AKT in bone tissue of the rats in model group were decreased(P＜0.01);compared with model group,the ratios of p-PI3K/PI3K in bone tissue of rats in different doses of VAP groups were increased(P＜0.05 or P＜0.01),and the ratios of p-AKT/AKT of the rats in alendronate sodium group and high dose of VAP group was increased(P＜0.01).Conclusion:VAP can improve PMOP in the rats,and its mechanisms may be related to the regulation of the PI3K/AKT signaling pathway and the reduction of oxidative stress in bone tissue by VAP.

Objective Because of statistical noise in Monte Carlo dose calculations,the effective point doses may not be accurately calculated.A user-defined sphere volume was adopted to substitute the effective point to take sphere sampling around the effective point,which minimize the random errors and improve the accuracy of statistical dose.Methods Direct dose measurements were performed at 0°and 90° using a 0.125 cm3 Semiflex ionization chamber (IC) 31010 isocentrically placed in the center of a homogeneous Cylindric sliced RW3 phantom (PTW,Germany).In the scanned CT phantom series,the sensitive volume length of the IC (6.5 mm) was delineated and the isocenter was defined as the simulated effective point.All beams were simulated in the treatment planning system (TPS) in accordance to the measured model.The grid spacing was calculated by 2 mm voxels and the relative standard deviation should be ≤ 0.5％.The statistical and measured doses were statistically compared among three IC models with different electron densities (ED;esophageal lumen ED =0.210 g/cm3 for model A,air ED =0.001 g/cm3 for model B and the default CT scanned ED for model C) at different sampling sphere radius (2.5,2.0,1.5 and 1.0 mm) to evaluate the effect of Monte Carlo.calculation uncertainty upon the dose accuracy.Results In the Monaco TPS,the statistical value was in the highest accordance with the measured value with an absolute average deviation of 0.49％ when the IC was set as esophageal lumen ED =0.210 g/cm3 and the sampling sphere radius was 1.5 mm.When the IC was set as air ED=0.001 g/cm3 and default CT scanned ED,and,the recommended statistical sampling sphere radius was 2.5 mm,the absolute average deviations were 0.61％ and 0.70％.Conclusion In the Monaco TPS,the calculation model with an ED of 0.210 g/cm3 and a sampling radius of 1.5 mm is recommended for the ionization chamber 31010 to substitute the effective point dose measurement to decrease the random stochastic errors of Monte Carlo.

Objective To figure out the optimal parameters of a volumetric modulated arc therapy ( VMAT) plan for cervical and upper esophageal cancer by quality evaluation of VMAT plans with different parameters, and to provide a reference for the design of clinical VMAT treatment plan. Methods Ten patients with cervical esophageal cancer and ten patients with upper esophageal cancer were enrolled as subjects. The Nucletron Oncentra 4. 3 treatment planning system was used to generate plans for Elekta Synergy VMAT accelerator. Six VMAT plans were made with variation in the gantry angle ( 2°, 3°, and 4°), the maximum delivery time (80 s, 110 s, and 150 s), and the collimator angle (0° and 45°). The doses to the planning target volume and organs at risk were analyzed by paired t test. Results For cervical and upper esophageal cancer, the quality of VMAT plans with a collimator angle of 45° was better than those with a collimator angle of 0°(P=0. 003?0. 007). For cervical esophageal cancer, there was no significant difference in quality between VMAT plans with a maximum delivery time of 110 s or 150 s and those with a maximum delivery time of 80 s ( P>0. 05 );for upper esophageal cancer, there was also no significant difference in quality between VMAT plans with three different maximum delivery times ( P>0. 05 ) . For cervical esophageal cancer, the VMAT plans with a gantry angle of 3° had a better quality than those with a gantry angle of 2° or 4°(P=0. 010?0. 048). For upper esophageal cancer, the VMAT plans with a gantry angle of 3° had a better quality than those with a gantry angle of 4° ( P=0. 010?0. 048) . Compared with those with a gantry angle of 2° , the VMAT plans with a gantry angle of 3° had a slightly better dose distribution in the target volume ( P=0. 046 ) , but a slightly higher dose to lung tissue ( V25 and V30 , P=0. 007 and 0. 026) . Conclusions The optimal initial parameters of a VMAT plan for cervical and upper esophageal cancer are a collimator angle of 45°, a maximum delivery time of 80 s, and a gantry angle of 3°.

Objective To construct the uniform electron density couch model (model A ED =0.25) and two components non uniform electron density couch model (model B FD =0.5and foam core=0.1) in the Monaco treatment planning system for the iBEAM(R) evo Extension 415,and to compare which model can better quantify the treatment couch influence on radiation dose.Methods Phantom was positioned in the center of the couch,the attenuation of the couch was evaluated with 6 MV for a field size of 10 cm× 10 cm.Dose measurements of couch attenuation were performed at gantry angles from 180.0° to 122.8°,using a 0.125cc semiflex ionization chamber (PTW),isocentrically placed in the center of a homogeneous cylindrical phantom.Each experimental setup was first measured on the linear accelerator and then reproduced in the TPS.By adjusting the relative-to water electron density (ED) values of the couch,the measured attenuation was replicated.The model accuracies of the model A and model B were evaluated by comparing the measured and calculated results at the minimum computational grid (2 mm) and maximum computing grid (5 mm),respectively.Results The maximum measured and calculated percentage deviation for the central phantom position was 4.01％.The couch model was included in the TPS with a uniform ED of 0.25 or a 2 component model with a fiber ED=0.5 and foam core ED=0.1.For model A and B under 2 and 5 mm voxel grid size,the mean absorbed dose with couch was reduced to 0.61％,0.84％,0.71％ and 0.92％from 2.8％ without couch.Conclusions Model A has a good agreement between measured and calculated dose distributions for all different voxel grid sizes and gantry angles.It can accurately describes the dose perturbations due to the presence of the couch and should therefore be used during treatment planning.

Objective To investigate the optimization of therapeutic regimen through the adjustment of the minimum sub-field area in intensity-modulated radiotherapy (IMRT) for cervical cancer,under the premise of no influence on the dose to target volume or organs at risk.Methods A total of 12 patients with pathologically confirmed cervical cancer were enrolled,and the prescribed dose to the planning target volume (PTV) was 50 Gy in 25 fractions.The Pinnacle 8.0m treatment planning system was used for all patients,and 16 IMRT plans were developed for each patient,with the application of 9 evenly distributed fixed incidence directions (0°,40°,80°,120°,160°,200°,240°,280°,and 320°),a minimum sub-field number of 80,and a minimum sub-field hop count (MU) of 5 MU.The range of sub-field area was 2-81 cm2.Direct machine parameter optimization was used for inverse-planned optimization calculation,and all the plans met the requirements of the clinical prescribed dose.The dose-volume histogram was used to evaluate the dose distribution in target volume and organs at risk.Results With the sub-field area increasing from 2 cm2 to 81cm2,the total hop count of IMRT plan was reduced from (1405±170) MU to (490±47) MU (P=0.000),and when the sub-field area increased above 6 cm×6 cm,the total hop count was reduced significantly (P=0.000).In the IMRT plan with a minimum sub-field area of 2-49 cm2,there was no significant difference in dose between the target volume and the organs at risk (P＞0.05).The dose to the rectum,the bladder,and both femoral heads showed no significant differences across the IMRT plans with different minimum sub-field areas (P＞0.05).Conclusions When the Pinnacle 8.0m treatment planning system is used to develop IMRT plans for cervical cancer,the requirements for clinical dose can still be met with a minimum sub-field area reaching 7 cm×7 cm,and there are significant reductions in sub-field hop count and total hop count.

Objective To investigate the application of the Monte Carlo dose calculation of output factors for electron beams in radiotherapy.Methods The code EGS4/MCTP was used to simulate the head of a medical linear accelerator (Varian 23EX) to calculate the output factors for 6 MeV,9 MeV and 18 MeV electron beams.The source-to-surface distance used was 100 cm.The field sizes ranged from 2 cm × 2 cm to 25 cm × 25 cm.The calculated output factors agreed with the corresponding measured factors which were measured by the IBA Phantom system to within 2％.Then,the output factors of direct articles and indirect articles which were under different energy and various cone-insert combinations were calculated by the code EGS4/MCTP.Results The calculated output factors agreement with the measurements is found to be mostly under the 1％ level.The variation of output factors depends on the characteristics of the beams and the modifications that the various cone-insert combinations introduce to these characteristics.Conclusions Monte Carlo dose calculations for electron beams in homogeneous water phantoms have been demonstrated to be accurate under the 1％ level in comparison with measurements.The output factors were influenced by energy and cone-insert combinations in complex ways.

Objective Comparing the dosimetric characteristics of volumetric modulated arc therapy (VMAT) and constant dose rate intensity modulated arc therapy (IMAT) in esophagus cancer to evaluate the performance of the two different arc therapy delivery techniques.Methods 22 cases of esophageal cancer patients were selected for the planning comparison study.All plans were done for IMAT and VMAT treatment plans on Oncentra 4.1 treatment planning system,prescription dose of 2 Gy in total 30 fractions.Planning objectives for PTV were at least 95％ reached the prescription dose and V110 no more than 10％.The maximum dose of spinalcord below 45 Gy and double lung dose V20 ≤ 28％,V30 ≤ 18％ were constrained.Plans were evaluated based on the ability to meet the dose volume histogram.The dose homogeneity index (HI),radiation conformity index (CI),radiation delivery time,monitor units and γ pass rate were also compared.SPSS 19.0 software paired ttest analysis was carried out on the two sets of data.Results The results showed that the IMAT plans in terms of the PTV's CI (t =3.35,P=0.003),D2(t =-2.27,P=0.034) lung's V30(t =-2.46,P=0.023) were better than that of VMAT group.But the VMAT plans spinal's V40 (t =2.37,P =0.027),lung's V5 (t =2.43,P =0.024) were superior to that of IMAT plans.There were no significant differences between IMAT and VMAT plans in the average dose of PTV,CTV,GTV,heart,spinal cord,double lung and the γpass rate.Conclusion IMAT presents a slight improvement in the OAR sparing in high dose with shorter treatment time when compared to VMAT.While in terms of delivered MU and tissue of low dose irradiated area is higher than that of in VMAT.These two treatment methods all can meet the clinical demand,which should be selected according to the actual situation of the patient.

Objective To measure the setup errors and organ movements of patients with esophagus carcinoma during radiotherapy and find a reasonable margin from the clinic target volume (CTV) to the planning target volume (PTV). Methods (1) Set-up veri cation: Forty-two cases of untreated esophageal cancer were enrolled into this study. The physicist firstly made the planning according to the doctor requests and ensured the best distribution at the target. Thereafter, the 0° and 90° digitally reconstructed radiograph (DRR) was transmitted to the iView GT workshop. Meanwhile, two copies of cross-cut electronic portal image (EPI) were required before radiotherapy. Two doctors confirmed the variance of the osteal mark from the EPI and DRR,and output a 3D direction (left to right, superior to inferior, anterior to posterior) of the setup errors through the iView GT software. (2)Breathing motion:Ten cases of untreated esophageal cancer were enrolled into this study.Three distinct breathing levels were deflned: FB (free breathing), EBH (expiration with breath-held) and IBH (inspiration with breath-held). We gave the treatment planning in FB, then by moving the isocenter to EBH and IBH, we recalculated the dose distribution without changing the field angle, shape and weighing (Mus). Displacements were analyzed at four points (anterior, posterior, right lateral and left lateral) and five levels of target (upper, quarter, isocenter, three-quarter and lower). Results (1) The systematic setup errors were -0.23 cm, -0.02 cm and -0.06 cm, and the random errors were 0.44 cm, 0.45 cm and 0.44 cm at the direction of left to right(LR), superior to inferior (SI), anterior to posterior(AP), respectively. (2) The organ movements were 0.3 cm, 0.6cm and 0.3cm at the LR, SI, AP, respectively. Conclusions As an alternative, the root-sum-of-squares of set-up error and organ motion are suggested by σtot=√ (σITV2+σSM2). The CTV to PTV margins are 0.8cm left to right, 0.78cm superior to inferior, 0.5cm anterior to posterior.

Objective To study the relationship between parameter settings in the intensity-modulated radiation therapy (IMRT) planning in order to explore the effect of parameters on absolute dose verification.Methods Forty-three esophageal carcinoma cases were optimized with Pinnacle 7.6c by experienced physicist using appropriate optimization parameters and dose constraints with a number of iterations to meet the clinical acceptance criteria.The plans were copied to water-phantem,0.13 cc ion Farmer chamber and DOSE1 dosimeter was used to measure the absolute dose.The statistical data of the parameters of beams for the 43 cases were collected,and the relationships among them were analyzed.The statistical data of the dosimetry error were collected,and comparative analysis was made for the relation between the parameters of beams and ion chamber absolute dose verification results.Results The parameters of beams were correlated among each other.Obvious affiliation existed between the dose accuracy and parameter settings.When the beam segment number of IMRT plan was more than 80,the dose deviation would be greater than 3％ ; however,if the beam segment number was less than 80,the dose deviation was smaller than 3％.When the beam segment number was more than 100,part of the dose deviation of this plan was greater than 4％.On the contrary,if the beam segment number was less than 100,the dose deviation was smaller than 4％ definitely.Conclusions In order to decrease the absolute dose verification error,less beam angles and less beam segments are needed and the beam segment number should be controlled within the range of 80.

ObjectiveTo evaluate correlation factors of cervical lymph nodes metastasis in thoracic esophageal carcinoma.MethodsLocal-regional metastasis of lymph node for 126 cases with esophageal squamous cell cancer after surgery from 2004 to 2009 were reviewed.Risk factors of cervical lymph nodes metastasis were examined by multiple Logistic regression analysis.ResultsIn 126 cases,supraclavicular lymph node metastasis rate was 43.7％ (55/126).By logistic regression,none of the primary site,T stage,N stage,histological grade,lymph node metastasis rate,lymph node metastasis degree and number of lymph nodes metastatic field was not the high risk of cervical lymph nodes metastasis.In addition,multivariate analysis found that lymph node metastasis in mediastinum region 1 was high risk factor for lymph node metastasis of region 1 ( x2 =12.14,9.27,P =0.000,0.002),lymph node metastasis in region Ⅲ and region 2 were high risk factors for lymph node metastasis of region Ⅱa ( x2 =14.56,8.27,8.02,3.93,P =0.000,0.004,0.005,0.047 ).ConclusionMediastinal para-recurrent nerve lymph node metastasis is a significant predictor for cervical lymph nodes metastasis.