OBJECTIVE: To estimate the primary electron beam parameters (PEB), including energy, radial intensity distribution and average angular divergence, of the individual linear accelerator using the Monte Carlo method. METHODS: A model of the treatment head and a standard field were built by BEAMnrc, and the dose distribution was simulated in water phantoms by DOSXYZnrc to obtain the percentage depth dose curve and off-axis ratio. By debugging the parameters mentioned above until the simulation and measurement results could match. RESULTS: The simulation and measurement results could achieve the best match when the parameters mentioned above were 6.25 MeV, 0.95 mm and 0.1° respectively. CONCLUSION The PEB of a linear accelerator could have a significant impact on the output beam characteristics. Monte Carlo estimation is one of the most crucial steps in establishing an individual linear accelerator model.
Monte Carlo Method ; Particle Accelerators ; Electrons ; Radiotherapy Dosage ; Phantoms, Imaging

Objective To investigate clinical significance and application of modified pelvic floor reconstruction developed by Peking Union Medical College Hospital ( MPFR ) in treatment of severe pelvic organ prolapse (POP) by comparing the effectiveness, quality of postoperative sexual life, life satisfaction and risk factors for POP recurrence with the following two surgical procedures: traditional total vaginal hysterectomy with anterior-posterior colporrhaphy (TVH-APC) and total vaginal hysterectomy with lateral colporrhaphy and sacrospinous ligament fixation and vaginal bridge repair and episiotomy (TVH-LC-SSLFVBR-EP). Methods Totally 173 patients with severe POP and at least two compartments defects of pelvic floor underwent surgeries in the study, 86 patients (group A) were treated by MPFR with polypropylene mesh application, 58 (group B) were treated by TVH-APC, and 29 patients (group C) were treated by TVH-LC-SSLF-VBR-EP. Peri-operative data and outcomes of postoperative courses at 6, 12, 18 months were collected and analyzed, in the meantime, the risk factors of recurrence were studied. Results (1) No statistical difference was observed among the above 3 groups in terms of length of operation, amount of blood loss, length of hospital stay, and morbidity after surgery ( P ＞ 0.05). ( 2 ) Cost hospitalization was ( 11 448 ±3049) Yuan in group A, which was significantly higher than (7262 ± 1607) Yuan in group B and (7140 ± 1817 ) Yuan in group C (P ＜ 0.05 ). (3) The length of vaginal cuff of (7.5 ± 1.4) cm in group A and ( 5.6 ± 1.1 ) cm in group C were significantly longer than (7.1±0.6) cm in group B ( P＜0.05). The width of vaginal cuff of (4.3±0.3) cm in group A was larger than (3.4±0.3) cm in group B and (3.3±0.4) cm in group C (P＜0.05). (4) The recurrence rate at 12 months after surgery was 12.8% (11/86)in group A, which was similar with 17.2%(5/29) in group C (P＞0.05) and significantly less than 36.2% (21/58) in group B (P＜0.05). The rate of active sexual life of 16.3% (14/86) in group A was significantly higher than 1.7% (1/58) in group B and 0 in group C ( P ＜ 0. 05 ). The index of life quality improvement at 12 months after surgery was 48±12 in group A, which was no less than 53±16 in group C ( P＞0.05) and higher than 27 ± 9 in group B ( P＜0.05). (5 ) Mesh rejection was observed in 6 patients in group A within 3 months after surgery, while the posterior vaginal wall was exclusively involved. No difference was found in urinary retention or urinary incontinence among three groups (P ＞0. 05 ). (6) The severe degree of POP, type of surgical procedure ( TVT-APC), anterior compartment defect of pelvic floor,and early days of performing pelvic floor reconstruction surgeries were high risk factors for POP recurrence (P＜ 0.05). Conclusions MPFR has a better curative effect and lower recurrence rate on patients with POP. It can help patients regain integrity of anatomical structure and functions of pelvic floor. TVH-LCSSLF-VBR-EP is also effective.

Objective To analyze the level and change trends of cancer mortality in the media focused area,Yingcheng of Hubei Province,to further support the authenticity and reliability of the information from media report.Methods Use the data of the first national retrospective death survey and the third national retrospective sampling death survey to describe cancer mortality and change trends in Yingcheng of Hubei Province.Results Crude cancer mortality in Yingcheng was 148.26/100 000.In the past 30 years,cancer mortality significantly increased by 9.27 times.Among 100 000 people in the county,each year 43 cases of malignant tumor death occurred more than the national average level.A variety of malignant tumors' mortality change in the county is significantly different from those of the country,such as esophageal cancer,stomach cancer did not fall but rise;liver cancer,lung cancer,leukaemia and colorectal cancer increased 5.84 times,5.61 times,5.07 times and 17.91 times more than the national average,respectively.The excess mortality rate of stomach cancer,liver cancer,lung cancer and colorectal cancer were 15.32/100 000,16.78/100 000,8.32/100 000 and 3.98/100 000 respectively.Negative binomial distribution fitting results suggest that death of stomach cancer exists village aggregation.Conclusions The level of historical cancer mortality in Yingcheng was low,but increase quickly,presently it is on the national high-incidence level.It presents the phenomenon that a variety of malignant tumors is generally on high-incidence level and stomach cancer exists village aggregation.

Objective: To describe the status and trend of dietary energy, protein and fat pattern of Chinese residents. Method : 23 470 households including 68 962 subjects were randomly sampled from 132 counties in 31 provinces, autonomous regions and the municipalities. The 24 h dietary recall method for 3 consecutive days was used in dietary survey and weighing method was used for condiment intake. Results: The average energy intake per reference man per day was 9.42 MJ (2 250.5 kcal), 11.8% and 29.6% from protein and fat respectively. The percentages of energy from fat of big city residents arrived 38.4%. The percentages of energy from cereals, animal food and pure energy food were 57.9%, 12.6% and 17.3% respectively. The average protein intake per reference man per day was 65.9 g, 52%, 7.5% ,25.1% and 15.3% from cereals, bean and bean product, animal food and other foods respectively. The average fat intake per reference man per day was 76.3 g, 39.2% from animal food. Conclusion: The dietary change of Chinese residents represents the characteristics of the transition period, including the decrease of energy and protein intake per capita, decrease of the percentage of dietary energy supplied by cereals and increase of fat intake per capita,especially from animal foods, and the proportion of energy contributed by fat.

control relatives.A ratio of s/q approached1/q with Penrose' s method.Heritability of SLE was78.8%?4.45%in the first-degree relatives,58.8%?10.9%in the second-degree relatives,and39.2%?32.0%in the third-degree relatives.The weighted mean heritability was75.2%?4.12%.Conclusions SLE has characteristics of polygenic disease.Genetic factor might play an important role in the liability of SLE.

Objective To evaluate the gene mutation of RANTES and CCR5 in SLE and its significance. Methods One hundred and forty-six definitive SLE patients and 159 controls were collected. SNPs of RANTES promoter and polymorphism of CCR5 were performed by PCR or PCR/RFLP assay, and further confirmed by direct DNA sequencing. Results The frequence of RANTES-403G/G compounded with 28C/C and CCR5/CCR5 was significantly different between SLE and control groups (72.6% vs 58.5%, P 0.05). Conclusions These results indicate that the two SNPs are linkage disequilibrium. Interaction of two SNPs in RANTES and CCR5 is related with SLE. RANTES-403G/G compounded with 28C/C and CCR5/CCR5 may be one of risk factors of SLE. RANTES-403A is probably related with renal damage of SLE.

Objective To examine the variation of protein expression in nasopharyngeal carcinoma cell lines with different biological characteristics and to identify the radiobiological associated proteins. Methods Biological characteristics of 5-8F and 6-10B were compared by flow cytometry assay after irradia- tion. The total proteins of 5-8F and 6-10B were separated by immobilized pH gradient(IPG) IEF-SDS two- dimensional gel electrophoresis technique. The differentially expressed proteins were cut from the gel and di- gested into peptides for MALDI-TOF MS and the Q-TOF mass spectrometric analysis. Identification of pro- tein was made through searching in protein sequence database. Protein expressions were examined by western blot and immunohistochemistry method. Results Nine most differentially expressed proteins between 5-8F cell and 6-10B cell were identified, p73 and CK19 expression examined by western blot were conformal with that by proteomic method, p73 expression in 5-8F cell was higher than in 6-10B cell. CK19 expression in 6- 10B cell was higher than in 5-8F cell. Conclusion Differentially expression of proteins exist in nasopha- ryngeal carcinoma cell lines with different biological characteristics. These proteins may be associated with cell radiobiological characteristic with the p73 as a potential biomarker.