Objective To evaluate the peripheral dose (PD) from megavoltage cone-beam CT (MVCBCT) imaging for head-and-neck region image-guided radiation therapy,to determine the correlation of PD with monitor unit (MU),and to investigate the impact of imaging field size on the PD.Methods Measurements of PD from MVCBCT were made with a 0.65 cm3 ionization chamber placed in a specially designed phantom at various depths and distances from the field edges.The PD at reference point inside the phantom was measured with the same ionization chamber to investigate the linearity between MU used for MVCBCT and the PD.The homogeneity of PD in the axial plane of the phantom were measured.Results PD from MVCBCT increased with increasing number of MU used for imaging and with increasing the field size.The measured PD in the phantom decreased exponentially as distance from the field edges increased.PD also decreased as the depth from the phantom surface increased.There was a strong linear relationship between PD and MUs used for MVCBCT.The PD was heterogeneous,with higher dose at the anterior than the posterior.Conclusions The PD from MVCBCT depend much on the MVCBCT delivery MU and the scan field size.In clinic,using the smallest number of MU allowable and reducing MVCBCT scanning field size without compromising acquired image quality is an effective method of reducing the PD.

Objective:To investigate the protective effects of quercetin on the periodontal tissue in Wistar rats with periodontitis. Methods:30 Wistar rats were randomly divided into 3 groups(n =1 0):Control group (group N),ligation group(group L)and liga-tion +quercetin group(group LQ).Bilateral first molars of the rats in group L and LQ were cervically ligated by an orthodontic wire with the diameter of 0.2 mm.The rats in group LQ were then treated with quercetin by gavage at 50 mg/(kg·d)after ligation.After 8 weeks,the rats were killed.Continuous slices of the periodontal tissue were made for HE staining and immunohistochemistry stai-ning.The morphological changes and the expression of TNF-αand COX-2 in the periodontal tissue were observed under light micro-scope.Results:The inflammatory cells and periodontal pocket were observed in group LQ were less than those in group L.The levels of TNF-α,COX-2 in group LQ were lower than that those in the group L(P <0.05).Conclusion:Quercetin has a protective effect on the periodontal tissues of Wistar rats with periodontitis.

Objective To compare the whole-body equivalent doses from volumetric modulated arc therapy (VMAT) and static intensity-modulated radiotherapy (IMRT) for patients with cervical cancer.Methods Nine patients with cervical cancer admitted to our hospital in 2014 were included in this study.Both VMAT and IMRT were planned for each patient.Each patient's personal dose equivalent (Hp (10)) was measured using thermoluminescent dosimeters placed at the xiphoid process and glabella during IMRT and VMAT.The whole-body equivalent doses were estimated based on the results measured at the xiphoid process and compared between the VMAT and IMRT techniques.The paired t test was used for difference analysis.Results The Hp (10) values measured at the xiphoid process and glabella of every patient were lower for VMAT than for IMRT.At a prescribed dose of 50 Gy,if the mean Hp (10) values measured at the xiphoid process were considered to represent the whole-body equivalent doses,the whole-body equivalent doses for VMAT and IMRT were 364 mSv and 538 mSv,respectively.Conclusions VMAT results in a lower whole-body equivalent dose to patients compared with IMRT.The decreased whole-body equivalent dose delivered by VMAT may reduce the likelihood of a radiation-induced secondary malignancy.

Screening for diabetes and its complications contributes to slowing the progression of diabetes mellitus. Based on the setting of grass-roots diabetes complication screening workstation with the concept of two stages of screening and three levels of prevention, we proposed a hospital-community-family integrated diabetes management strategy. This article discusses the background, organization structure, operation mechanism and implementation process of this strategy, aiming to provide reference for constructing a suitable and practical grass-roots diabetes management model.

Objective To investigate the impact of adopting different dose grid resolution during volumetric modulated arc therapy (VMAT) planning on COMPASS pass rate.Methods A total of 10 patients with cervical cancer were enrolled.Four types of VMAT plans (plan1,plan2,plan3,plan4) were designed for each patient,with dose grid resolution of 0.2 cm × 0.2 cm × 0.2 cm,0.3 cm × 0.3 cm ×0.3 cm,0.4 cm ×0.4 cm ×0.4 cm and 0.5 cm ×0.5 cm ×0.5 cm,respectively.The plans were exported to Linac and conducted,then measured by COMPASS.The discrepancies were analyzed,which were obtained by comparing reconstructed dose from COMPASS and dose from TPS optimization.Results For tumor volume,the mean value of Dmean and D95 were ＜ 0.5％ and ＜ 1.3％ respectively,and the standard deviation were both ＜ 1.0％.For organs at risk (OAR),the max discrepancies were Dmean of femur with-6.7％,-7.0％,-8.0％,-5.8％,and V35 of rectum with 4.9％,-6.3％,-6.1％,-5.7％ in four types of VMAT plans.The γ (3％,3 am) rate of tumor volume was ＞95％ with standard deviation ＜ 2.5％,with no statistically significant difference among the four types of plans (P ＞0.05).The γ (3％,3 mm) rate of OARs were ＞ 98％ except femur (＞ 95％),and the standard deviations were within 1.9％-6.1％,with no statistical significance (P ＞0.05).The average γ rate of tumor volume and OARs were ＜ 0.4 except femur (＞ 0.4),with no statistically significant difference among four types of VMAT plans (P ＞ 0.05).Conclusions COMPASS pass rate was not influenced by the dose grid resolution between 0.2 ～ 0.5 cm for VMAT plan.

Objective:To investigate the independent and combined effects of maternal smoking during pregnancy and offspring genetic susceptibility on overall cancer mortality.Methods:Based on the United Kingdom Biobank ( n=419 228) data, the Cox proportional hazard regression model was used to estimate the effect of maternal smoking during pregnancy on offspring overall cancer (including 16 cancers in men and 18 in women) mortality and its combined effect and interaction with offspring genetic factors. Results:Maternal smoking during pregnancy was significantly associated with a 13% increased risk of overall cancer mortality in men [hazard ratio( HR)=1.13, 95% CI: 1.06-1.20] and 19% increased risk in women ( HR=1.19, 95% CI: 1.11-1.27). Participants with high genetic risk had the highest overall cancer mortality than those with low genetic risk (men: HR=1.42, 95% CI: 1.30-1.55; women: HR=1.38, 95% CI: 1.25-1.52). Compared with participants without maternal smoking during pregnancy and low genetic risk, those with maternal smoking during pregnancy and high genetic risk were associated with a 56% increased risk of overall cancer mortality in men ( HR=1.56, 95% CI: 1.37-1.77) and 59% in women ( HR=1.59, 95% CI: 1.39-1.83). Conclusion:Maternal smoking during pregnancy may increase offspring overall cancer mortality and more severe harm in individuals with high genetic risk.

Objective:To investigate the impact of air pollution on dynamic changes in lung function and further explore the association between genetic factors and lung function and its changes.Methods:Research data were from 14 506 participants in the United Kingdom Biobank with two complete baseline and follow-up lung function tests. Particulate matter [including particulate matter with aerodynamic diameter ≤2.5 μm and ≤10 μm (PM 2.5 and PM 10)], nitrogen dioxide (NO 2), and nitrogen oxides (NO x) concentrations were estimated using land-use regression models. Annual changes in lung function were calculated based on baseline and follow-up lung function tests. Polygenic risk scores (PRS) of lung function [forced expiratory volume in the first second (FEV 1), forced vital capacity (FVC), and the ratio of FEV 1 to FVC (FEV 1/FVC)] were constructed by genetic variations. The association between air pollution concentrations and lung function changes was analyzed by multiple linear regression models, and the impact of genetic factors on lung function and its changes was also assessed. Results:PM 2.5, PM 10, NO 2, and NO x showed a negative correlation with FVC changes [PM 2.5: -6.66 (95% CI: -9.92- -3.40) ml/year; PM 10: -0.40 (95% CI: -0.77- -0.03) ml/year; NO 2: -1.84 (95% CI: -2.60- -1.07) ml/year; NO x: -1.37 (95% CI: -2.27- -0.46) ml/year]. Additionally, PM 2.5, PM 10and NO 2 were also negatively correlated with changes in FEV 1 [PM 2.5: -3.19 (95% CI: -5.79- -0.59) ml/year; PM 10: -3.00 (95% CI: -5.92- -0.08) ml/year; NO 2: -0.95 (95% CI: -1.56- -0.34) ml/year]. PRS of lung function were positively correlated with baseline lung function (FVC, FEV 1, and FEV 1/FVC) and lung function changes (all β>0, all P<0.001). In different PRS stratification analyses, the effect of air pollution on lung function changes remained significant, and there was no apparent heterogeneity. Conclusions:PRS of lung function are significantly associated with baseline and lung function changes. Long-term exposure to air pollution accelerates the decline of lung function indicators such as FVC and FEV 1. The effects of air pollution are consistent in individuals with different genetic risk scores.