Association between low ambient temperature during pregnancy and adverse birth outcomes: A systematic review and meta-analysis / 中华医学杂志(英文版)

BACKGROUND@#Extreme temperature events, including extreme cold, are becoming more frequent worldwide, which might be harmful to pregnant women and cause adverse birth outcomes. We aimed to investigate the association between exposure to low ambient temperature in pregnant women and adverse birth outcomes, such as preterm birth, low birth weight, and stillbirth, and to summarize the evidence herein.@*METHODS@#Relevant studies were searched in PubMed, Cochrane, and Embase electronic databases until November 2021. Studies involving low ambient temperature, preterm birth, birth weight, and stillbirth were included. The guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-analyses were followed to conduct this study risk of bias and methods for data synthesis.@*RESULTS@#A total of 34 studies were included. First, pregnant women exposed to low ambient temperature had an increased risk of preterm birth (risk ratio [RR] 1.08; 95% confidence interval [CI] 1.04-1.13). Subgroup analyses revealed that exposure during late pregnancy was more likely to induce preterm birth. In addition, only pregnant women exposed to <1st percentile of the mean temperature suffered increased risk of preterm birth. Moreover, pregnant women living in medium or hot areas were more prone to have preterm births than those in cold areas when exposed to low ambient temperatures. Asians and Blacks were more susceptible to low ambient temperatures than Caucasians. Second, pregnant women exposed to low ambient temperature had an increased risk of low birth weight (RR 1.07; 95% CI 1.03-1.12). Third, pregnant women had an increased risk of stillbirth while exposed to low ambient temperature during the entire pregnancy (RR 4.63; 95% CI 3.99-5.38).@*CONCLUSIONS@#Exposure to low ambient temperature during pregnancy increases the risk of adverse birth outcomes. Pregnant women should avoid exposure to extremely low ambient temperature (<1st percentile of the mean temperature), especially in their late pregnancy. This study could provide clues for preventing adverse outcomes from meteorological factors.@*REGISTRATION@#No. CRD42021259776 at PROSPERO ( https://www.crd.york.ac.uk/PROSPERO/ ).

Effect of salvianolic acid on behaviors and brain inflammatory factors in depression model rats / 中华行为医学与脑科学杂志

Objective:To investigate the effect of salvianolic acid on depressive behavior in depression model rats induced by chronic mild stress (CMS) and its mechanism.Methods:Fifty healthy male clean grade Sprague-Dawley(SD) rats were divided into five groups according to a random number table with 10 in each group: control group (nCMS+ Nal group), CMS+ normal saline group (CMS+ Nal group), CMS+ fluoxetine group (CMS+ Flu group), CMS+ salvia acid group (CMS+ Sal group), CMS+ fluoxetine+ Salvia acid group (CMS+ Flu+ Sal group). Except the control group, the rats in the other four groups were all received CMS modeling for 21 days. Twenty-one days after CMS modeling, rats were intraperitoneally injected with 0.9% normal saline (10 mg·kg -1·d -1), fluoxetine (20 mg·kg -1·d -1), salvia acid(40 mg·kg -1·d -1), fluoxetine(20 mg·kg -1·d -1)+ salvia acid(40 mg·kg -1·d -1)for 21 days. During the administration period, rats in the other four groups continued to receive CMS intervention for 21 days. Forced swimming test and sucrose preference test were conducted at baseline (day 0), after modeling (day 21) and after intervention (day 42) so as to evaluate depression like behavior. Then the rats were sacrificed and the hippocampus and prefrontal cortex were taken. The mRNA levels of Toll like receptor 4 (TLR4) and myeloid differentiation primary response 88 (MyD88) were detected by RT-qPCR. The cytokines including interleukin-1β(IL-1β), interleukin-2(IL-2), interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) were detected by Luminex technique.SPSS 21.0 was used for statistical analysis.Repeated measurement ANOVA was used for behavioral data analysis, one-way ANOVA was used for molecular index data analysis, and Spearman was used for correlation analysis. Results:The results of repeated measurement ANOVA showed that the interaction effects between group and time of body mass, sucrose preference, forced swimming immobility time were significant at baseline, after modeling and after intervention ( F=18.238, 6.921, 7.591, all P<0.05). After modeling, compared with nCMS+ Nal group, the rats in CMS+ Flu group, CMS+ Sal group, CMS+ Flu+ Sal group and CMS+ Nal group had lower body weight, lower sucrose preference rate and longer forced swimming immobility time (all P<0.05). After intervention, compared with CMS+ Nal group(body weight (350.15±41.65)g, sucrose preference(52.95±11.13)%, static time(91.40±15.22)s), the body weight((378.21±30.78)g, (385.12±43.19)g, (391.41±31.21)g, (402.33±18.67)g, all P<0.05) and sucrose preference((69.30±15.56)%, (68.12±10.99)%, (71.18±9.51)%, (75.47±11.55)%, all P<0.05) of CMS+ Flu group, CMS+ Sal group, CMS+ Flu+ Sal group and nCMS+ Nal group were all increased, while the forced swimming immobility time ((68.81±21.74)s, (66.10±25.51)s, (63.53±22.32)s, (71.21±21.41)s, all P<0.05) were shorter (all P<0.05). After intervention, among the body weight, sucrose preference and the immobility time of CMS+ Flu group、CMS+ Sal group and CMS+ Flu+ Sal group, there were no differences between each two groups(all P>0.05). After intervention, the levels of TLR4 mRNA and MyD88 mRNA in prefrontal cortex and hippocampus of CMS+ Flu group, CMS+ Sal group, CMS+ Flu+ Sal group and nCMS+ Nal group were all lower than those in CMS+ Nal group (all P<0.05). In prefrontal cortex, the levels of TLR4 mRNA (0.715±0.358) and MyD88 mRNA (0.739±0.233) in CMS+ Flu+ Sal group were lower than those in CMS+ Sal group (1.943±0.606, 1.815±0.897) (both P<0.05). The level of TLR4 mRNA in prefrontal cortex and hippocampus of rats were positively correlated with the level of MyD88 mRNA and TNF-α level and forced swimming immobility time and negatively correlated with sucrose preference rate (prefrontal cortex r=0.915, 0.041, 0.027, -0.178, all P<0.05; hippocampus r=0.810, 0.070, 0.011, -0.153, all P<0.05). Conclusion:The antidepressant effect of salvianolic acid is presumedly achieved by inhibiting the immunoinflammatory response mediated by the TLR4/Myd88 signaling pathway in CMS rats.

Nursing students′ occupational hazards status between China and Sweden / 中国实用护理杂志

Objective@#To get a general information about the occupational hazards status of nursing students between China and Sweden, to provide effective basis for reducing occupational exposure rate.@*Methods@#Questionnaire survey. Design and develop an occupational hazards questionnaire and translate the questionnaire into Swedish.@*Results@#The correct rate of occupational hazard in Chinese nursing students including mechanical, chemical, biological and physical hazards was 94.4% (1 024/1 085) and 89.8% (557/620), respectively. 81.6% (1 898/2 325), 90.7% (703/775), both higher than Swedish nursing students 58.4% (756/1295), 48.8% (361/740), 60.2% (1 671/2 775) 86.7% (802/925), the difference was statistically significant (χ2 =259.196-1 259.183, P<0.05). Only "operating posture is not standard will lead to the occurrence of low back pain" "Women need to wear gloves when intravenously injecting patients" "Women need to wear gloves when changing medicines for patients" "Women need to wear gloves when drawing blood for patients" 4 questions correct answer rate Sweden Nursing students were higher than Chinese nursing students (χ2=11.738-16.990, P<0.01), and the remaining questions of Chinese nursing students were higher than Swedish nursing students (χ2=11.738-45.464, P<0.01).@*Conclusions@#Nursing students in China and Sweden generally have the awareness of occupational hazard cognition, and Chinese nursing students have a better grasp of the knowledge of occupational hazard cognition, but there are still weak links, which need to be improved from the aspect of education, managers should also consider reducing the occupational exposure of nursing students and even nurses from the management level, improve the employment quality of nursing students and nurses.

Nursing students′ occupational hazards status between China and Sweden / 中国实用护理杂志

Objective:To get a general information about the occupational hazards status of nursing students between China and Sweden, to provide effective basis for reducing occupational exposure rate.Methods:Questionnaire survey. Design and develop an occupational hazards questionnaire and translate the questionnaire into Swedish.Results:The correct rate of occupational hazard in Chinese nursing students including mechanical, chemical, biological and physical hazards was 94.4% (1 024/1 085) and 89.8% (557/620), respectively. 81.6% (1 898/2 325), 90.7% (703/775), both higher than Swedish nursing students 58.4% (756/1295), 48.8% (361/740), 60.2% (1 671/2 775) 86.7% (802/925), the difference was statistically significant ( χ 2 =259.196-1 259.183, P<0.05). Only "operating posture is not standard will lead to the occurrence of low back pain" "Women need to wear gloves when intravenously injecting patients" "Women need to wear gloves when changing medicines for patients" "Women need to wear gloves when drawing blood for patients" 4 questions correct answer rate Sweden Nursing students were higher than Chinese nursing students ( χ 2=11.738-16.990, P<0.01), and the remaining questions of Chinese nursing students were higher than Swedish nursing students ( χ 2=11.738-45.464, P<0.01). Conclusions:Nursing students in China and Sweden generally have the awareness of occupational hazard cognition, and Chinese nursing students have a better grasp of the knowledge of occupational hazard cognition, but there are still weak links, which need to be improved from the aspect of education, managers should also consider reducing the occupational exposure of nursing students and even nurses from the management level, improve the employment quality of nursing students and nurses.

Analysis of clinical features and motility characteristics of ineffective esophageal motility / 中华消化杂志

Objective To clarify the correlation between the clinical characteristics,esophageal motility features and esophageal acid exposure in patients with ineffective esophageal motility (IEM). Methods From January 2016 to March 2018,at Peking University First Hospital,22 IEM patients diagnosed by esophagus high-resolution manometry (HRM ) and 24 individuals with normal HRM results were enrolled. Clinical features,parameters of esophageal HRM and results of esophageal 24-hour pH monitoring of IEM patients and the individuals with normal HRM results were compared. According to the median distal contraction integral (DCI)of ten swallows,the IEM patients were divided into mild-IEM group (DCI 250 - 450 mmHg · s · cm (1 mmHg = 0. 133 kPa))(14 cases)and severe-IEM group (DCI < 250 mmHg·s·cm)(eight cases). The clinical features and esophageal motility were compared between normal HRM group,mild-IEM group and severe-IEM group. T test,chi-square test and one-way analysis of various were used for statistical analysis. Results The age of IEM group was older than that of normal HRM group ((64. 5 ± 11. 2)years vs. (50. 3 ± 18. 2)years),and the difference was statistically significant (t = - 3. 135,P = 0. 003). The lower esophageal sphincter pressure (LESP)of IEM group was lower than that of normal HRM group ((17. 0 ± 6. 8)mmHg vs. (22. 3 ± 7. 2)mmHg),and the difference was statistically significant (t = 2. 516,P = 0. 016). There were 15 cases in normal HRM group and 14 patients in IEM group who underwent esophageal 24-hour pH monitoring and there were five and two patients with abnormal acid exposure time (AET)in normal HRM group and IEM group,respectively. The length of proximal esophageal body (PEB)pressure zone of severe-IEM group was shorter than those of normal HRM group and mild-IEM group ((2. 8 ± 1. 5 )cm vs. (4. 2 ± 0. 7 )cm and (4. 6 ± 0. 9)cm),and the differences were statistically significant (t = 2. 397 and 3. 432,P = 0. 044 and 0. 003). The integrated relaxation pressure (IRP)and LESP of normal HRM group were both higher than those of mild-IEM group ((9. 3 ± 2. 9 )mmHg vs. (7. 2 ± 3. 3 )mmHg,(22. 3 ± 7. 2 )mmHg vs. (15. 4 ± 7. 1)mmHg),and the differences were statistically significant (t = 2. 148 and 2. 843,P = 0. 038 and 0. 007). There were six and eight patients in mild-IEM group and severe-IEM group who underwent esophageal 24-hour pH monitoring,respectively,and two patients in mild-IEM had abnormal AET. Conclusions The LESP of IEM patients is low. The clinical features and AET of IEM patients are not associated with the severity of IEM. In patients with severe IEM,the proximal and distal esophageal contractility is weakened,and the length of PEB pressure zone is shortened.

Analysis of clinical features and motility characteristics of ineffective esophageal motility / 中华消化杂志

Objective@#To clarify the correlation between the clinical characteristics, esophageal motility features and esophageal acid exposure in patients with ineffective esophageal motility (IEM).@*Methods@#From January 2016 to March 2018, at Peking University First Hospital, 22 IEM patients diagnosed by esophagus high-resolution manometry (HRM) and 24 individuals with normal HRM results were enrolled. Clinical features, parameters of esophageal HRM and results of esophageal 24-hour pH monitoring of IEM patients and the individuals with normal HRM results were compared. According to the median distal contraction integral (DCI) of ten swallows, the IEM patients were divided into mild-IEM group (DCI 250-450 mmHg·s·cm (1 mmHg=0.133 kPa)) (14 cases) and severe-IEM group (DCI<250 mmHg·s·cm) (eight cases). The clinical features and esophageal motility were compared between normal HRM group, mild-IEM group and severe-IEM group. T test, chi-square test and one-way analysis of various were used for statistical analysis.@*Results@#The age of IEM group was older than that of normal HRM group ((64.5±11.2) years vs. (50.3±18.2) years), and the difference was statistically significant (t=-3.135, P=0.003). The lower esophageal sphincter pressure (LESP) of IEM group was lower than that of normal HRM group ((17.0±6.8) mmHg vs. (22.3±7.2) mmHg), and the difference was statistically significant (t=2.516, P=0.016). There were 15 cases in normal HRM group and 14 patients in IEM group who underwent esophageal 24-hour pH monitoring and there were five and two patients with abnormal acid exposure time (AET) in normal HRM group and IEM group, respectively. The length of proximal esophageal body (PEB) pressure zone of severe-IEM group was shorter than those of normal HRM group and mild-IEM group ((2.8±1.5) cm vs.(4.2±0.7) cm and (4.6±0.9) cm), and the differences were statistically significant (t=2.397 and 3.432, P=0.044 and 0.003). The integrated relaxation pressure (IRP) and LESP of normal HRM group were both higher than those of mild-IEM group ((9.3±2.9) mmHg vs. (7.2±3.3) mmHg, (22.3±7.2) mmHg vs. (15.4±7.1) mmHg), and the differences were statistically significant (t=2.148 and 2.843, P=0.038 and 0.007). There were six and eight patients in mild-IEM group and severe-IEM group who underwent esophageal 24-hour pH monitoring, respectively, and two patients in mild-IEM had abnormal AET.@*Conclusions@#The LESP of IEM patients is low. The clinical features and AET of IEM patients are not associated with the severity of IEM. In patients with severe IEM, the proximal and distal esophageal contractility is weakened, and the length of PEB pressure zone is shortened.

Effect of single prolonged stress in different pregnant time on the emotion and cognitive function of adult offspring rats / 中华行为医学与脑科学杂志

Objective To investigate the effect of prenatal stress (PS) at different pregnant time on emotion and cognition of adult offspring rats.Methods Twelve healthy female Sprague Dawley (SD) rats were randomly divided into control group(CON,n=4),the early pregnancy group(PS1,the 1～ 7 days of pregnancy,n=4) and the late pregnancy group(PS3,the 15 ～ 21 days of pregnancy,n=4).The pregnant rats were exposed to single-prolonged stress(SPS) on gestational day 7 or 15 respectively,except control group.The offspring were measured every weekend from 1-7 week after birth.At the eighth weekend,the sucrose intake (anhedonia) and Morris water maze (MWM) were performed to assess depression-like behavior and spatial learning and memory.Results The body weight of the first to seventh weeks after birth showed that there was a statistically significant difference among the three groups (F=28.207,P＜0.01),and there was a significant difference in time effect (F=1 041.546,P＜0.01).The body weight of two PS groups was significantly lower than those of control group(P＜0.05).The body weight of PS3 was lower than that of PS1 significantly(P＜0.05).Sucrose preference:PS3((27.70± 19.31) ％) were reductive on sucrose consumption than CON significantly((66.93±19.67) ％)(P＜0.05)while PS1 ((89.80±6.79) ％) increased in sucrose consumption compared with the CON significantly(P＜0.05).MWM:in training stage the difference of average avoid latency was existed in the three groups of the first 5 days(F=11.121,P＜0.01).Similarly,there was a significant difference in measure time(F=91.327,P＜0.01),the escape latency of the PS3 was decreased,while PS1 was significantly increased compared with CON;in testing stage,PS3 ((54.50±4.64) s,(53.21±4.45)) showed a significant increase in the duration in target site and numbers of times across the target site compared with CON((32.24±.4.17) s,(31.68±4.00)) (P＜0.05).Conclusion The acceptance of stress in the late pregnancy may lead to depression like behavior in the adult offspring and also enhance the learning and memory ability.And acceptance of stress in early pregnancy can cause impairment of learning and memory ability in adult offspring rats.

Development of an superparamagnetic immunochromatographic test strip for rapid quantification of CA72-4 / 实用医学杂志

Objective To establish a simple and practical superparamagnetic immunochromatographic test strip for rapidly monitoring human serum level of CA72-4. Methods Water-soluble carboxylated super-paramagnetic nanoparticles were prepared with a modified one-step hydrothermal synthesis method. Magnetic probe was prepared by immobilizing specific antibody (mAb1) onto the surface of nanoparticles. Following with optimization and assembly of the test strip , we evaluated sensitivity , specificity , stability of this method for serum CA72-4 detection. Results The optimized test strip provided not only the qualitative results, but also the high sensitivity quantitative detection through stable magnetic signal. The detection limit was 0.83 IU/mL. One hundred clinical samples ( 70 positive and 30 negative ) were measured to assess these test strips with high sensitivity (99%) and high specificity (93%). The test strip and magnetic signal possessed high stability. Conclusion A rapid and quantitative detection of CA72-4 by the test strip was accomplished. This method is rapid, sensitive and quantitative, possessing great potential in large sample screening or in-home testing.

Research progress of assessment instruments and evaluation index of sleep disorders / 中国实用护理杂志

This paper reviewed the subjective and objective evaluation tools of sleep disorders, and summarized evaluation indicators of sleep disorders, so as to provide a theoretical support and practical reference for the diagnosis of sleep disorders, intervention and related researches.

Effect of transitional care intervention on quality of life for patients with chronic obstructive pulmonary disease:a Meta-analysis / 中国实用护理杂志

Objective To evaluate the effect of transitional care intervention on quality of life for patients with chronic obstructive pulmonary disease (COPD). Methods The Cochrane library, PubMed, Embase, Chinese biomedical literature database(CBM), Chinese scientific journals full-text database, Wanfang data were searched up to June 2015 to identify randomized controlled trials(RCTs) comparing continuity of patient care with conventional treatment.The data were analyzed using Revman 5.2 software. Results 26 RCTs involving 2 443 participants were included.The results of Meta-analysis showed continuity of care couldreduce the scores of The COPD Assessment Test [ SMD=-2.24, 95%CI=(-3.52--0.96), P<0.01],and St George′s Respiratory Questionnaire [SMD=-0.26, 95%CI(-0.50--0.02), P≤0.05], and could improve the scores of Chronic Respiratory Disease Questionnaires [SMD=0.46, 95%CI(0.08-0.84), P≤0.05]. Conclusions Transitional care can improve the quality of life of patients with COPD.

Therapeutic effect of taurine against aluminum-induced impairment on learning, memory and brain neurotransmitters in rats.

The aim of the study was to demonstrate the therapeutic effect of taurine against aluminum (Al)-induced neurological disorders in rats. Forty-two Wistar rats were randomly allotted into six groups: control (saline only), Al exposure (281.4 mg/kg/day for 1 month), Al + taurine (Al administration as previously plus taurine, doses were 200, 400 and 800 mg/kg/day, respectively, for the next 1 month) and prevention group (along with the Al administration as previously, 400 mg/kg/day taurine was treated for 1 month. During the next 1 month, rats were given taurine 400 mg/kg/day only). Starting from the sixth week, the body weight gain was significantly reduced in Al exposure group compared with saline (P < 0.05), and at the eighth week, the gain in prevention group was increased compared with Al (P < 0.05). Brain coefficient was gained in Al exposure compared with saline or prevention group (P < 0.05). Al exposure resulted in learning and memory impairment by increasing the escape latency and searching distance, meanwhile, decreasing the swimming time in the quadrant of platform and the numbers of crossing the platform (P < 0.05). Unsurprisingly, taurine treatment (400, 800 mg/kg/day and prevention) significantly protected against Al-induced brain dysfunction (P < 0.05). The Al exposure led to significant decreases in levels of γ-GABA and Tau, meanwhile, increased in level of Asp and Glu compared with saline (P < 0.05). And yet, taurine treatment partially reversed the deteriorated changes. The results suggested that taurine probably has neuroprotective effect against Al-induced learning, memory and brain neurotransmitters dysfunction.

Cone beam CT image iterative reconstruction based on Split-Bregman method / 南方医科大学学报

<p><b>OBJECTIVE</b>We propose a new iterative reconstruction method based on split-Bregman method with tight frame regularization for effective and accurate reconstruction of the sparse-view cone beam CT image.</p><p><b>METHODS</b>A tight frame was chosen as the regularization term for the objective function, so that the image reconstruction involves only the minimization of an objective function according to the compressed sensing theory. We utilized the split-Bregman method to tackle the task of minimization in three steps: (1) a fast calculation of the forward projection matrix; (2) introducing an intermediate variable to transform the non-differentiated L1 regularization term into the differentiated L2 regularization problem, and solving the target function using conjugate-gradient method; (3) updating the intermediate variable using shrinkage formula from Bregman method.</p><p><b>RESULTS</b>Digital and physical phantom experimental results suggested that our new approach had great advantages in terms of image quality, reconstruction time, and applicability.</p><p><b>CONCLUSION</b>The proposed method can accurately reconstruct CBCT image with limited data to lower the X-ray dose and accelerate the calculation speed in comparison with the POCS method.</p>

ART reconstruction from few views using bilateral-filtering iterative method / 生物医学工程学杂志

An algebraic image reconstruction from few views using bilateral-filtering iterative method was proposed due to the problem of computed tomography insufficient data in the present study. In each iteration reconstruction, we first used algebraic reconstruction technique (ART) algorithm to reconstruct an image, ensuring the non-negativity of the reconstructed image at the same time, and then performed bilateral-filtering to the above-mentioned image. In order to improve reconstructed image quality and accelerate the convergence speed, we developed a modified bilateral-filtering method. Shepp-Logan simulation experiments and real CT projection data reconstructions showed the feasibility of the algorithm. The results showed that, compared with the traditional methods of filtered back projection (FBP), ART and GF-ART,the proposed method has a higher signal-to-noise ratio, and maintains more effectively the image edge information.

A method for rapidly removing ring artifacts in CT image / 南方医科大学学报

<p><b>OBJECTIVE</b>To propose a new method for effectively and rapidly removing the ring artifacts in CT images based on image post-processing.</p><p><b>METHODS</b>The CT image with ring artifacts in the Cartesian coordinate was first transformed into an image with line artifacts in the polar coordinate. The image in the polar coordinate was then filtered by designing a one-dimensional filter to calculate the mean and variance of each pixel after filtering, which were compared with the variance threshold value and the pixel threshold value to determine the position of the artifacts for corrections accordingly. Finally, the polar coordinate image was converted into Cartesian coordinate image.</p><p><b>RESULTS</b>Simulated and actual CT data experimental results demonstrated the efficiency of this method for removing artifacts, retaining the image fidelity and reducing the processing time.</p><p><b>CONCLUSION</b>The new method can accurately recognize the position of the artifacts and effectively remove them to facilitate the clinical diagnosis.</p>

Verification of the accuracy of Monte Carlo-based dose calculation algorithm, DPM, in homogeneous and inhomogeneous tissues / 生物医学工程学杂志

The present paper is to verify the accuracy of DPM, a Monte Carlo-based dose calculation algorithm, in homogeneous and inhomogeneous tissues. DPM was applied to calculate (1) depth dose curves and off-axis ratios at a depth of 10 cm in water using a 6 MeV photon beam with a 3 cm x 3 cm field and phase space file simulated Varian 60 degrees C medical linear accelerator with a 10 cm x 10 cm field at SSD = 100 (cm); (2) depth dose curves using 6 MeV photon beam in inhomogeneous tissues, such as water (6 cm)/lung (6 cm)/water (8 cm) with a 3 cm x 3 cm field and water (6 cm)/ bone (2 cm)/water (12 cm) with a 10 cm x 10 cm field; (3) depth dose curves using 6 MeV photon beam based on the CT data of a patient's head and abdomen. The doses based on DPM are compared to the doses calculated by DOSXYZnrc under the same condition. The error was within 3% in water phantom while the error was within 3% in inhomogeneous tissues, except a few points. It has been concluded that the DPM can accurately predict the dose to homogeneous and inhomogeneous tissues.

Preliminary application of an improved Demons deformable registration algorithm in tumor radiotherapy / 南方医科大学学报

<p><b>OBJECTIVE</b>To validate the efficiency of an improved Demons deformable registration algorithm and evaluate its application in registration of the treatment image and the planning image in image-guided radiotherapy (IGRT).</p><p><b>METHODS</b>Based on Brox's gradient constancy assumption and Malis's efficient second-order minimization algorithm, a grey value gradient similarity term was added into the original energy function, and a formula was derived to calculate the update of transformation field. The limited Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) algorithm was used to optimize the energy function for automatic determination of the iteration number. The proposed algorithm was validated using mathematically deformed images, physically deformed phantom images and clinical tumor images.</p><p><b>RESULTS</b>Compared with the original Additive Demons algorithm, the improved Demons algorithm achieved a higher precision and a faster convergence speed.</p><p><b>CONCLUSION</b>Due to the influence of different scanning conditions in fractionated radiation, the density range of the treatment image and the planning image may be different. The improved Demons algorithm can achieve faster and more accurate radiotherapy.</p>

Monte Carlo simulation of 6 MV medical electron linear accelerator / 中华放射医学与防护杂志

Objective To analyze the influence of the mean energy and the full-width of half msximum(FWHM)of incident electron beam intensity distilbution(assumed Gaussian distribution)on depth dose curves and off-axis ratios and to derive a most optimal combination of mean energy and FWHM of incident electron beam intensity distribution.Methods The study simulated 6 MV photon beam produced by Varian 600C medical linear accelerator with OMEGA/EGSnrc by matching the relative error of calculated and measured depth dose curves past depth of maximum dose and off-axis ratios at a depth of 10.0 cm in water within 2%.Results The depth dose curves were relatively insensitive to the mean energy past depth of maximum dose and the FWHM of the incident electron beam intensity distribution.Dose profiles were sensitive tO the mean energy and FWHM.The dose profiles horns decreased as the mean energy and tlle FWHM of the ineident electron beam intensity distilbution increased.The calculated value of the depth dose curves matched well with the measured value.The calculated value of the off-axis ratio was consistent with the measured value within the radiation field.However, the maximum errors of individual measurement points in the penumbra region and OUt of the field reached 18.5%.Conclusions In the field.the most optimal combination of mean energy and FWHM of incident electron beam intensitv distribution Can be derived, however,can not be derived out of the field and in the penumbra region.