Occupational exposures of Chinese medical radiation workers in 1986-2000

Data on occupational exposures from medical uses of radiation in China during 1986-2000 are presented. Individual dose monitoring results in the reports of monitoring centres in different provinces in China during 1986-2000 were collected as the basic data. These data were summarised and then analysed. From 1986 to 2000, in diagnostic radiology, nuclear medicine and radiotherapy, the annual collective effective doses varied within the range 122.4-206.6, 5.4-9.3 and 4.1-10.3 man Sv, respectively; the average annual effective dose in these categories varied within the range 1.5-2.2, 1.2-1.6 and 1.0-1.5 mSv, respectively. Almost all the average annual effective doses in medical uses of radiation were <3 mSv in 1986-2000, and no monitored workers were found to have received an occupational exposure >50 mSv in a single year or >100 mSv in a 5-y period. After 1990, the protection status of medical radiation workers in China was sufficient.     

医用X射线机管电压的测量与调整

X射线机管电压的失准，会直接影响诊断质量和射线管的使用寿命，本文介绍了几种测量与调整管电压的方法，供检修人员参考。     

Measurements of X ray absorbed doses to dental patients in two dental X ray units in Nigeria

Measurements of absorbed doses from radiographic examinations to various anatomical sites in the head and neck of patients with an average age of 45 years using intra-oral dental radiography have been carried out. LiF (TLD-100) dosemeters were used for the measurements of the absorbed dose. The measured absorbed doses to the various anatomical sites in the two units are reported, discussed and compared with results from the literature. Quality control measurements were also performed using a Victoreen quality control test device on the X ray units. The tube voltage accuracies for the two units were found to be within acceptable limits (less than +/- 10%). On the other hand the exposure time accuracies for these units have large deviations (>20%). These results and those that have been reported in the literature may be an indication that high patient doses are common in most dental X ray centres and countries. As a result of this, regular compliance and performance checks of dental diagnostic X ray equipment are essential in order to ensure proper performance and to minimise unnecessary patient and operator doses.     

影响医用诊断X射线机计量性能的主要因素分析

本文通过对影响医用诊断X射线机计量性能的主要因素分析探讨,为进行维修、调整提供参考.进一步说明对X射线机进行计量检定的必要性和重要意义.     

The potential for reduction of radiation doses to patients undergoing some common X ray examinations in Tanzania

The potential for patient dose reduction in diagnostic radiology was investigated in five major Tanzanian hospitals. The aim of this study was to follow up previously reported suggestions for improved practices to achieve dose reductions. The suggestions were implemented and entrance surface dose measurement repeated by using well-calibrated LiF thermoluminescence dosemeters. The results show that dose reductions in chest PA X ray examinations ranged from 15% to 50%. For abdomen AP and pelvis AP X ray examinations, the dose reductions ranged from 24% to 73% and from 25% to 72%, respectively. The respective dose reductions for lumbar spine AP and LAT projections ranged from 4% to 58% and from 16% to 77%. Interestingly, the majority of radiographs obtained after the implementation of dose reduction measures were useful for intended diagnosis according to the opinion of radiologists. It is concluded that significant dose reductions can be achieved in the country without loss of diagnostic information. Such dose reductions also predict reductions of radiation risk to patients.     

Thermoluminescent and dosimetric properties of X ray phosphors

Rare earth doped oxide, phosphate, etc. are radioluminescent phosphors that have a broad application in X ray imaging, in luminescent screens, image transformers and in fluorescent lamp manufacturing. Some of them have interesting thermoluminescence features as well, which makes the phosphors applicable also in dosimetry. Two of these materials are Sr3(PO4)2 and BaFCl activated with europium. The general radioluminescence (RL) and thermoluminescence (TL) characteristics of these materials was investigated earlier and the preliminary results have already been published elsewhere. The aim of the present work is to investigate the interesting properties of these phosphors mainly from a dosimetric point of view (sensitivity, dose dependence, etc.).     

医用X射线机射线管真空度降低对检定结果的影响

本文介绍了医用X射线机X射线管真空度降低产生的原因及对检定结果的影响.     

交流电阻计量标准通过验收

2007年1月19日，受科技部委托，由国家质检总局在中国计量科学研究院主持召开了科技部基础性工作专项《国家现代电学计量标准和检测体系的建立和完善》子课题“交流电阻计量标准”的课题验收会。     

A reassessment of Galileo radiation exposures in the Jupiter magnetosphere

Earlier particle experiments in the 1970s on Pioneer-10 and -11 and Voyager-1 and -2 provided Jupiter flyby particle data, which were used by Divine and Garrett to develop the first Jupiter trapped radiation environment model. This model was used to establish a baseline radiation effects design limit for the Galileo onboard electronics. Recently, Garrett et al. have developed an updated Galileo Interim Radiation Environment (GIRE) model based on Galileo electron data. In this paper, we have used the GIRE model to reassess the computed radiation exposures and dose effects for Galileo. The 34-orbit 'as flown' Galileo trajectory data and the updated GIRE model were used to compute the electron and proton spectra for each of the 34 orbits. The total ionisation doses of electrons and protons have been computed based on a parametric shielding configuration, and these results are compared with previously published results.     

Neonatal doses from X ray examinations by birth weight in a neonatal intensive care unit

The aim of this study was to investigate the frequency and type of X ray examinations performed on neonates classified according to their birth weight in a neonatal intensive care unit (NICU). In this study, the radiology records of 2408 neonates who were admitted to the NICU of Oita Prefectural Hospital between January 1994 and September 1999 were investigated. This study revealed that the neonates with earlier gestational ages and lower birth weights required longer NICU stays and more frequent X ray examinations made using a mobile X ray unit. The average number of X ray examinations performed on neonates of less than 750 g birth weight was 26 films per neonate. In regard to computed tomography and fluoroscopy, no significant relationship was found between the birth weight and number of X rays. This study revealed that the entrance-surface dose per neonate was dependent upon the birth weight, while the maximum dose was not dependent upon the birth weight. The average neonatal dose in the NICU was predominantly from computed tomography and fluoroscopy. The individual dose varied widely among neonates.     

Semiconductor and thermoluminescent dosimetry of pulsed soft X ray plasma sources

A multichannel detection system having a dynamic range of approximately 1 x 10(-9) Gy --20 Gy was developed with the use of commercially produced Si-photodiodes and TLDs for accurate measurement of X ray energy emitted from plasma-focus facility and from laser-produced plasmas. The proof of linearity of the employed detectors accomplished by a comparison of their responses to a broad band spectrum of X rays emitted from plasmas, is reported. It is demonstrated that TLDs irradiated with no protective filter show an incorrect response due to overloading in the sub-keV range and repopulation of dosimetric peaks induced by the UV radiation. The measurement of the power of undesirable secondary X ray sources driven by the primary plasma inside the interaction chamber was performed on the basis of analysis of space dependence of X ray intensity with respect to the assumed r(-2) decrease in the intensity far away from the plasma.     

高精度X射线双晶衍射仪的原理及其应用

本文介绍了Ｘ射线双晶衍射仪的特点及其原理，以及利用Ｘ射线摇摆曲线技术在半导体材料研究方面的应用。     

Evaluation of occupational exposures to natural radiation in the Czech Republic

The Czech approach to limit the occupational exposures to natural radiation is based on the rules given by the Atomic Act and by the Decree of the State Office for Nuclear Safety (SONS) on radiation protection. Workplaces with potential risk of increased exposure to natural sources are specified explicitly. A new method to perform the above-mentioned measurements and to determine the effective doses of workers was proposed in 2005 and accepted by the SONS in 2007. The first experience illustrates its applicability.     

大菱鲆病原鳗弧菌生物学及分子特征研究

从山东沿海养殖发病大菱鲆分离了5株鳗弧菌。5株菌对大菱鲆有较强的致病性,LD50范围为2.32×101～4.03×102cfu/g鱼;5株菌分别属于O1、O2、O3血清型,菌株之间的16SrRNA基因序列相似性范围97.1%～99.9%;与国外报道的鳗弧菌的序列相似性范围为89.7%～99.9%。5株菌的生理生化特征与鳗弧菌标准菌株一致,能产生多种胞外酶和溶血素;都含有金属蛋白酶基因和溶血素基因,其中3株菌各含有一个67kb大质粒。病原菌对青霉素、苯唑青霉素、氨苄青霉素、先锋霉素Ⅳ、先锋霉素Ⅴ、先锋霉素Ⅵ、链霉素、强力霉素、洁霉素、万古霉素、灭滴灵等11种常用抗菌药物有抗性,只对新生霉素、呋喃妥因、利福平、新霉素等4种药物敏感。     

Assessment of personal exposures to optical radiation in large entertainment venues

Workplace exposure to optical radiation from artificial sources is regulated in Europe under the Artificial Optical Radiation Directive 2006/25/EC implemented in the UK as The Control of Artificial Optical Radiation at Work Regulations 2010. The entertainment environment often presents an extremely complex situation for the assessment of occupational exposures. Multiple illumination sources, continuously changing illumination conditions and people moving during performances add further complexity to the assessment. This document proposes a methodology for assessing the risks arising from exposure to optical radiation and presents detailed case studies of practical assessment for two large entertainment venues.     

Intercomparison on the usage of computational codes in radiation dosimetry

'QUADOS', a Concerted Action of the European Commission, has run an intercomparison aimed at evaluating the use of computational codes for dosimetry in radiation protection and medical physics. This intercomparison was open to all users of Monte Carlo, analytic and semi-analytic codes or deterministic methods. Its main aim was to provide a snapshot of the methods and codes currently in use. It also intended to furnish information on the methods used to assess the reliability of computational results and disseminate 'good practice' throughout the radiation dosimetry community. Eight problems were selected for their relevance to the radiation dosimetry community, three of which involve neutron transport. This paper focuses on the analysis of the neutron problems.     

X射线多晶面探测器衍射系统及其应用

介绍了目前世界上先进的粉末衍射系统——X射线多晶面探测嚣衍射系统的主要配置、工作原理、二维衍射几何关系以及X射线多晶面探测器衍射系统在材料学研究中的典型应用，重点讨论了在金属的晶体学织构和应力研究中的应用。     

Induction of chromosome aberration in human lymphocytes and its dependence on X ray energy

The variations of dose response with X ray energy observed with the human lymphocyte dicentric assay is examined. In order to determine reliably the initial slopes (RBEm) many cells need to be analysed at low doses. Insufficient analysis may explain some reported interlaboratory differences in fitted dose-response coefficients. One such discrepancy at 150 kVp, E = 70 keV is examined. Data are also presented for an X ray spectrum of 80 kVp, E = 58 keV. Over the photon energy range 20 keV X rays to 1.25 MeV gamma rays RBEm varies by about a factor of 5, with the lower energies being more effective. This is consistent with microdosimetric theory. By contrast, in radiological protection a radiation weighting factor of 1.0 is assumed for all photons when assessing the risk of inducing cancer at low doses. The measured variations of biological effect with photon energy have led to suggestions that the lower energies, as used for some diagnostic radiology, carry a greater risk per unit dose than is normally assumed by those involved in radiological protection. Interpretation of the data reported in this paper does not support this view.     

Calculation and usage of containment monitor radiation readings during PWR accidents

A computer code named CALCON for calculation of containment monitor radiation readings is introduced. The validity of the code was verified by comparison with data given in IAEA technical documents. The contribution of isotopes to containment readings under conditions of core melt, gap release and normal coolant release were investigated. The conclusions were that the radiation reading in containment is mainly from iodine and noble gases when sprays are off, and the radiation reading is mainly from noble gases when sprays are on, and during the beginning hours when radionuclides are released into containment, the monitor readings will decrease rapidly. Curves of containment radiation readings versus shutdown time for DAYA BAY nuclear power plant were calculated using CALCON.     

HgCdTe探测器应力的多重晶X射线衍射分析

HgCdTe光伏探测器的钝化介质膜应力常常限制其低温性能,利用高分辨率多重晶X射线衍射仪中的三重晶衍射技术和倒易空间作图对钝化介质膜应力进行了表征,发现在较高溅射能量下沉积的钝化膜,由于应力的作用,HgCdTe晶片出现弯曲,并有大量镶嵌结构,而在较低的溅射能量下和热蒸发下沉积的钝化膜,晶面未出现明显弯曲,可获得较低应力的钝化介质层。