The UDRS interlocking fault is a common dose interlocking of Varian high-energy linear accelerator. Due to the complexity of the system, this fault has brought challenges to the engineers for a long time. Hence, an effective solution is urgently required. In this article, the circuit and principle for UFRS interlocking fault for Varian CLINAC-IX linear accelerator were explicitly analyzed and the maintenance methods were summarized. The management methods of such rare fault were shared, aiming to provide reference for subsequent management of similar interlocking faults.

Objective To guarantee the quality of measurenents with the radon-thoron discriminative detectors of our laboratory.Methods LD-P radon-thoron discriminative detector participated in the international intercomparison for integrating radon/thoron detectors organized by National Institute of Radiological Science (NIRS,Japan).Detectors were sent to NIRS for exposure.Radon intercomparison was conducted with radon chamber providing three levels of exposure:low,medium and high levels.Thoron intercomparison was carried out at thoron chamber,which also provided three levels of exposure:low,medium and high levels.Detectors were posted back to our laboratory for etching and analysis after exposure.Then the measured values were submitted to NIRS.Finally the reference values were informed of us.Results The relative percent difference (RPD) between the measured value and the reference value for radon was-13.8％,-14.4％ and-17.1％ at low,medium and high levels respectively,and that of thoron were-14.4％,8.9％ and-3.2％ at three levels respectively.Conclusions Both radon and thoron measurement of our detectors rank asCategory Ⅰ in the 4th international intercomparisons for integrating radon/thoron detectors with the NIRS radon/thoron chambers.

Objective To study the seasonal variation of indoor 222Rn and 220Rn concentrations in Longdong district,Gansu Province.Methods A total of 44 houses from 5 different types of raw soil architectures and 5 ordinary brick houses from a typical area were selected in Longdong district,Gansu Province in China.The LD-P discriminative 222Rn and 220Rn detectors were used to measure the indoor concentrations of 222Rn and 220Rn during four seasons in one year.Results The indoor concentrations of 222Rn showed a significant seasonal variation,which varied with different types of houses.222Rn concentrations of ordinary brick houses,soil brick houses and the cave dwellings were higher in winter and autumn and lower in summer.The average concentrations of 222Rn were 55.3-90.3 Bq/m3 in winter,36.4-65.7 Bq/m3 in spring,35.6-63.9 Bq/m3 in summer,and 60.7-87.2 Bq/m3 in autumn.For cave dwellings,open-cut cave dwellings and the underground cave dwellings,222Rn concentrations were higher in summer and autumn,and lower in winter and spring.The average concentrations of 222Rn ranged from 139-184 Bq/m3 in winter,135-199 Bq/m3 in spring,179-252 Bq/m3 in summer,172-242 Bq/m3 in autumn.The seasonal variation of indoor 220Rn was basically consistent in six types of houses,and lower in winter and spring and highest in autumn.The average concentrations of 220Rn ranged from 43.4-64.3 Bq/m3 in winter,60.6-537 Bq/m3 in spring,77.7-792 Bq/m3 in summer,63.2-1077 Bq/m3 in autumn.The indoor concentrations of 222Rn and 220Rn were different among different types of houses,and they were generally higher in type of raw soft architectures than in that of ordinary brick houses.Conclusions 222Rn concentrations indoors showed a significant seasonal variation and varied with different types of houses.

Objective To study the in vitro effects of sonodynamic management on human ovarian cancer cell line HRA. Methods Hematoporphyrin was selected as a sonosensitizer and ultrasound with certain intensity was used to activate hematoporphyrin.Then MTT assay and clony-forming efficiency assay were applied to determine the growth inhibitory effects of ovarian cancer cells. Electron microscope was applied to detect the morphological changes of the cells. Cell apoptosis was analyzed using flow cytometry. Results Hematoporphyrin had no significant inhibitory effects on the cells. However, when hematoporphyrin was used before ultrasound,it could enhance the killing effects of ultrasound(P

Objective To use Monte Carlo method to build a shielding calculation model for the proton and heavy ion treatment room,and to provide a reliable calculation method for shielding design.Methods A Monte Carlo-based FLUKA code was adopted to build the shielding calculation model for the proton and heavy ion treatment room,and to simulate the radiation field distribution in the proton and heavy ion treatment room.The calculation model was verified through the radiation detection around the proton and heavy ions treatment room.Results The FLUKA code-based simulation results were consistent with the radiation detection.Conclusions The shielding calculation model based on FLUKA code can simulate the radiation field from proton and heavy ions.Among the secondary particles,secondary neutrons are the dominant component and the main concern of accelerator shielding design.In shielding calculation,the emphasis should be put on both beam intensity and energy.

Objective To measure the circuit time constants of 4 kinds of radiation survey meters (451P ionization chamber dosimeter,6150AD6 + 6150AD-b dose meter,FH40G + FHZ672E-10 dose meter and AT1123 dose meter) and,to discuss the formula of time response correction and its application.Methods In the condition of continuous exposure of X-ray machine,the ambient dose equivalent rates shown by survey meters were recorded.In order to get the circuits time constant,the least squares fittingmethod was used to fit the data using the time response formula of circuit having a capacitance C and a resistance R in series.Results The relative uncertainty of fitted circuit time constants was higher than 20％ except for 6150AD6 + 6150AD-b dose meter.The relative uncertainty of fitted r was 8％ for 6150AD6 + 6150AD-b dose meter.Conclusions The time required to stabilize the dosimeter readings was 8,5,3 and 2 s,respectively,for the 451P ionization chamber dosimeter,6150AD6 +6150AD-b dose meter,FH40G + FHZ672E-10 dose meter and AT1123 dose meter.The rising trend of their measured values was not fully accordance with the RC circuit time response correction formula.

Objective To investigate the current situation of radiation protection in nuclear medicine diagnosis workplace.Methods The study was performed in 3 hospitals in northeast,north and central of China from February to December in 2013.The γ dose rate instrument was used to detect the workplace ambient dose equivalent rate of medicine preparation,leaching,packing,injection and imaging.Individual effective dose and equivalent dose were evaluated by photoluminescent dosimeter.Results The ambient dose equivalent rate was up to 1.92 mSv/h at repacking place and 1.2 mSv/h at injection place.The ambient dose equivalent rate of patients after injection was 5.36-240 μ,Sv/h.The hand equivalent dose was 0.01-0.02 mGy.Moreover,there were problems of staff route intersection,as well as the patients after injection staying in the public area.Conclusions Radiation workers should pay more attention to individual protection,and improve the operation proficiency to shorten the operation time.Furthermore,in order to protect public from unnecessary irradiation,there should be some changes in staff route and patients administration.

OBJECTIVE To investigate the effects of lead exposure on the permeability,secretion and transportation function of blood-cerebro-spinal fluid barrier (BCB)of rats in order to provide the theo-rical basis for elucidating the mechanis m of lead induced neurotoxicity.MEHTODS 60 SPF SD rats were rando mly divided into 4 groups,including a control group and three doses lead exposed groups. Rat in the lead exposure groups were given drinking water containning 0.05%,0.1 % and 0.2% lead acetate (at dose of 80,160,320 mg·kg -1 )for 8 weeks.Laser scanning confocal microscopy was uti-lized to determine the lead content in seru m,cerebrospinal fluid (CSF)and choroid plexus sa mples. Morris maze was used to test learning and me mory.Fe moral artery perfusion of Evans blue (EB)and fluorescein sodiu m (NaFI)was performed to measure BCB permeability function.Confocal laser scan-ning was applied to detect junction adhesion molecule (JAM)and occludin protein expression in choroid plexus.ELISA was used to measure the concentration of transthyretin (TTR)and leptin in seru m and CSF.RESULTS The lead content in seru m,choroid plexus and CSF significantly increased,especially the lead level in CSF.Morris water maze data showed that escape latency of rat in lead acetate 160 and 320 mg·kg -1 group were 52 ±12,(89 ±19)s,respectively,longer than that of control group 〔(28 ±7)s, P<0.05〕.The ti mes across platform of rats in lead acetate 160 and 320 mg·kg -1 group were lower than that of control group(P <0.05).The NaFI content in CSF of rats in all lead acetate exposure groups were 0.94 ±0.09,1 .02 ±0.03 and (1 .08 ±0.18)mg·L -1 ,respectively,and were higher than those of control group〔(0.74 ±0.04)mg·L -1 〕;While the EB content in CSF of rat in lead acetate 160 and 320 mg·kg -1 group were higher than the control group(P <0.05),which indicated that lead acetate exposure at low dose can lead to the increase of permeability of BCB.Laser scanning confocal micro-scope i mages showed that the JAM protein expression of choroid plexus in lead acetate 160 and 320 mg·kg -1 group were 44.9% and 42.9% of the control group.Sa me decline was seen in terms of occludin expression.The TTR content of CSF of rats in lead acetate 80 mg·kg -1 group was (32.3 ± 1 1 .7)ng·g -1 protein,lower than that of the control group,and the difference was significant.This decline was also noted in lead acetate 160 and 320 mg·kg -1 group.The data of TTR in CSF suggested that the low dose lead acetate exposure can disrupt the BCB secretion function.The leptin levels in CSF of lead acetate 160 and 320 mg·kg -1 group were lower than that in the control group (P <0.05 ). CONCLUSION Lead exposure did disrupt the permeability,transportation and secretion function of BCB.Our data suggest that BCB dysfunction might be involved in the mechanis m of lead induced neurotoxicity.

Objective To study the effect of radon exhalation on the external dose model for building material,so as to provide the scientific and precise assessment of external radiation exposure hazard.Methods The mechanism of exhalation of radon from building material was analyzed,mathematical model of correction factor for the effect of radon exhalation was derived and resolved by Matlab program and the relationship between correction factor and diffusion length,surface emanation coefficient and thickness of building material was discussed.The absorbed dose rate induced by several classical building materials was calculated and compared.Results The radon exhalation correction factor was independent of diffusion length and thickness of building material in most cases.Negative correlation was found between radon exhalation correction factor and radon surface emanation coefficient.Radon exhalation correction factor numerically equals to '1-radon surface emanation coefficient'.The relative percentage deviation between absorbed dose rate induced by several classical building materials was in the range of 2.23％-10.02％,for both corrected and uncorrected radon exhalation effects.Conclusions Radon exhalation from building material has a certain effect on external dose model for building material,which should attract attention.It is important to conduct the correction for external dose model by introducing ‘1 -radon surface emanation coefficient’ as the radon exhalation correction factor,in order for the scientific assessment and control of external radiation exposure hazards from building materials.

Objective To develop kinesthetic and visual imagery questionnaires applicable to Chinese stroke survivors and evaluate their test-retest reliability,inter-rater reliability and internal consistency.Methods The English version of a kinesthetic and visual imagery questionnaire (KVIQ) was translated into Chinese using wellaccepted questionnaire translation procedures.Thirty stroke survivors were each assessed twice using two versions of the translation (the KVIQ-20 and the KVIQ-10) by two experienced raters with an interval of 7 days between the tests.The test-retest reliability,inter-rater reliability and internal consistency of the visual imagery score (visual imagery subscale),the kinesthetic imagery score (kinesthetic imagery subscale) and the total scores for the KVIQ-20 and KVIQ-10 versions were analyzed.Results The test-retest coefficients,the inter-rater reliability correlation coefficients and Cronbach's alphas for the KVIQ-20 version ranged from 0.879 to 0.945,from 0.894 to 0.936 and from 0.867 to 0.919,respectively.The corresponding measurements for the KVIQ-10 vcrsion were 0.914 to 0.953,0.852 to 0.900 and 0.827 to 0.878.Conclusion Both the KVIQ-20 and KVIQ-10 Chinese instruments have shown good testretest and inter-rater reliability and good internal consistency in assessing stroke survivors.Either is an effective tool for assessing their motor imagery ability.