Objective:To analyze the performance of single-photon emission computed tomography (SPECT) spatial resolution so as to provide reference for the selection of mathematical function algorithms in formulating test standard of SPECT performance.Methods:Using the general test phantom to acquire the Digital Imaging and Communications in Medicine image (DICOM) of three performance parameters included intrinsic spatial resolution power, system spatial resolution power and plane spatial resolution power of whole body.And 10 measured data of 3 performance parameters were randomly obtained, and then parabola algorithm and Gaussian algorithm were adopted to implement fitting calculation and measurement for these data, respectively, and the difference of the two algorithms was further analyzed.Results:The range of fitting determination coefficient (R2) of Gaussian algorithm of three performance parameters that obtained from SPECT was from 0.974 to 0.999.And the test P values of intrinsic spatial resolution power, system spatial resolution power and plane spatial resolution power of whole body were 0.0001, 0.057 and 0.075, respectively.Conclusion:The analysis of spatial resolution performance of SPECT may adopt parabolic algorithm.And the system spatial resolution power should gather the data of 256×256 matrix.

Objective To investigate the lens and pituitary dose impacted by additional filtration and collection field in head and neck DSA examinations. Methods All images were acquired by a Philips ALLura Xper FD 20 DSA machine. The combination of the different collection fields (48 cm, 42 cm, 31 cm, 22 cm) and additional filtrations (0.9 mmCu+1.0 mmAl, 0.4 mmCu+1.0 mmAl, 0.1 mmCu+1.0 mmAl) were adjusted when the anthropomorphic phantom filled with dosimeter was scanned in anterioposterior and lateral positions with 2D?DSA and 3D?DSA. The dose area product (DAP), air kerma (AK) and the radiation dose values of bilateral lens and pituitary were measured and recorded. The 2D and 3D?DSA regional absorption dose on lens and pituitary were analyzed using t' test, the correlations between DAP and AK parameters and different regional absorption doses were evaluated by Pearson rank correlation coefficient. Results Absorption doses of left lens, right lens and pituitary with 2D?DSA (n=12) were as following:(2.77 ± 0.68), (6.23 ± 3.54), (8.65 ± 2.62) mGy, while the parameters with 3D?DSA (n=12) were (1.78 ± 0.82), (2.18±1.15), (3.32±0.64) mGy, respectively;the results revealed a significant difference (t'=3.20, 3.76 and 6.85, P<0.01). DAP [(8 739±5 731) mGy·cm2] had a relationship with absorption dose of pituitary, left lens and right lens [(5.988 ± 3.299),( 2.258 ± 0.872),( 4.207 ± 3.303) mGy, r values were 0.766, 0.684, 0.727; P<0.01]. AK values was (31 ± 23) mGy and it had a relationship with pituitary absorption dose (r value was 0.894, P<0.01). The lens dose was reduced when the additional filtration was increased and the collection field was decreased, the radiation dose of the pituitary was reduced when both the additional filtration and the collection field were increased. Conclusions In the head and neck DSA examinations, the radiation dose of the lens and the pituitary had different changes with the different additional filters and collecting fields. The organ dose with 3D?DSA was significantly less than that with 2D?DSA.

Objective: To research and design a new model for SPECT quality control testing, which is consistent with the national standards of geometry and materials, and has a lot of advantages, including the optimized and reasonable structure, convenient to use, high efficiency, and little exposure dose for testing personnel. Methods: To investigate current international and domestic standard protocols for the purpose of confirming the key parameter; to optimize the design based on the characteristics of γradiation detection and prevention, and improve the capability of the available technologies. Results: The process of research and design includes:1. Lead Grid model, applied to test the“inherent spatial resolution”and“inherent spatial differential linearity”of the SPECT system, with one die body endowed with bidirectional application as X/Y;2. Dual Linear Source model, used to test“the system spatial resolution (mm)”and“the whole body spatial resolution (mm)”, as well as the“the system spatial resolution (mm)”of double detectors;3. Plane Source model, applied to the simultaneous test of“system plane sensitivity”of the double detectors;4. Holder of Radioactive Source with low scattering. 5. Others for connecting and supporting. 6. Data acquisition and analysis software. This new model has obtained 4 patent licenses. Conclusion:This new model is easy to use, highly effective. It could lessen the dosage of 99Tcm, reduce the radiation injury of personnel. In the future, we need improve the structure of model to reduce radiation dose further, and make a positioning standard for lead grid model during quality control detectingin China, and this work also lay the foundation for the further work in the quality control of the dental panoramic machine.

Objective To explore the inlfuence of different anode/iflter combinations on image quality in digital mammography to choose the optimal anode/iflter combination for mammary glands with different densities. Methods The digital mammography of the phantom used to simulate human breast tissue was conducted under semi-automatic exposure mode through four kinds of anode/iflter combinations including Mo/Mo, Mo/Rh, Rh/Rh and W/Rh. The exposure conditions and radiation doses were recorded while the calcification points, ifbrous tissues and clumps of the phantom were evaluated through the analysis on phantom images according to ACR scoring standard.Results The skin incident dose and average mammary glandular dose of Mo/Mo were highest and those of W/Rh were lowest while those of Mo/Rh and Rh/Rh were moderate. The resolution ratio of clumps and ifbrous tissues of Mo/Mo was best and that of W/Rh was worst while that of Mo/Rh and Rh/Rh was moderate.Conclusion Different anode/iflter combinations are suitable for the digital mammography of mammary glands with different densities, which indicates that the actual thickness and density of breast should be considered to choose the exposure condition in clinic.

Objective To explore the benefit from eye-lens dose reduction and the impact on the clinical imaging quality using orbital bismuth shield in infant head CT.Methods According to the width and length of the patients' eyes,the eye-shield was modified for infant sizes.An infant head CTDI phantom was scanned twice with and without eye-lens bismuth shielding.The infant CT head protocols were 120 kV,130 mA with axial sequential scanning.The thermoluminescence detectors (TLD) were used to detect the organ dose of eye lens.Ninety-nine infant cases clinically suspected intracranial hemorrhage were scanned with the same CT scanning protocol.Two senior radiologists scored the image quality and evaluated the consistency of scores.Results The radiation dose for eye-lens was reduced by 32％ on phantom test.The rate of accepted imaging was 92％ and κappa value between two radiologists was 0.78.Conclusions The eye-shield could reduce doses to eve-lens significantly in infant head CT scanning with acceptable image quality.

美国Catphan 500 CT性能测试模体已得到全球知名CT生产公司的认同,都用它来标示CT机的成像性能.该模体较依据AAPM 1977年1号报告生产加工的注水模体有很多优点:因是固体模体,没有漏水的问题;储运箱能当模体支架,模体能探出扫描床外;低对比度分辨力模体由同一种物质不同密度材料制成等.

Objective To determine the response time and time resolution correct factor for the first range of both the ion chamber survey meters. Methods A formula based on the circuit theory and the definition of response time was established, and verified with experiment data. Results The response time at the first range(0-50 μSv/h) of the model 451B and the model 451P ion chamber survey meter were 13.2 s and 7.3 s, respectively. Conclusions The time resolution correct coefficients should be used to inspect the radiation protection level by both the ion chamber survey meters.

Objective To investigate the mammography-use status in Beijing and provide reliable data for government.Methods The X-ray instruments were tested according to MQSA、ACR and EUR16260EN by using model8000 X-ray testing system and the whole QA、QC phantom instruments.Results The qualified rate of X-ray instruments(including computed radiography,digital X-ray photography and screen-film system)was not high.Conclusion Quality control is highly-needed.

目的了解本市介入放射学诊疗程序中受检者的剂量,加强介入诊疗的放射防护。方法采用热释光剂量计元件(TLD)贴敷在受检者的体表处,测量并算出被照射区域及临近器官皮肤入射剂量,调查4家医院的心、脑及周围血管的9种155例介入放射诊疗手术。结果平均剂量值超过1Gy/次的手术有:PTCA、肝动脉造影、全脑造影加装支架、下肢动脉造影。所观察的PTCA和全脊髓造影术中剂量大于1Gy的分别达20%和38%。3例PTCA剂量达10~12.9Gy/次,脑血管介入手术时眼晶体、甲状腺最大剂量分别达295mGy、595mGy;脊髓血管介入手术时性腺最大剂量达100mGy。结论对剂量大于2Gy的受检者皮肤损伤应观察、随访和治疗,手术中对重要器官进行防护,建立辐射危害告之制度、强化操作者放射防护的“剂量意识”。

Objective To identify and control medical radiation risk during the period of the 29th Olympic Game and to provide perfect medical radiological service for the Olympic Game. Methods Investigating on-site, data searching, testing on the spot, experimenting in laboratory and referring to exponential matrix of risk(AS/NZS 4360∶1999) are adopted. Simultaneously, Excel and Access programs are employed to set up a special database of medical radiation risk. Results It is reported that there are 986 medical radiological units including 902 radiological diagnosis places, 31 radiotherapy organizations and 53 workplaces with nuclear medicine. At the same time, 6 091 radiation workers engage in radiological diagnosis, radiotherapy and nuclear medicine, and the numbers of radiation workers with the three kinds of occupations account for 85.1%、7.0% and 7.9% respectively. In addition, it is shown that the average effective dose equivalent (E) from X radiological diagnosis that are received by Beijing’s resident is 0.27 mSv·a-1,which is approximately equivalent to 33% of the E from developed country and is trifold to the national average value (E). According to the assessment, the index of medical radiation risk including radiotherapy is 52 which is equivalent to high dangerous risk level, while medical radiation risk from radiological diagnosis can be regarded as a low-middle dangerous radiation risk because of its risk index ranges from 20 to 36. Conclusion All effective protective measures should be taken to control medical radiation risk and to vindicate the safety of radiological diagnosis and radiotherapy with the Olympic Game because of complicated factors and comprehensive distribution of medical radiation risk in Beijing.

Objective To identify and assess radiation risk in Beijing Olympic Game in 2008,so as to provide scientific data for controlling radiation risk and guaranteeing the Olympic Game.Methods According to the relevant national standards, codes and byelaws, several methods including literature review, consultation from experts and experience analysis were adopted to carry out the systematic research work on the basis of referring the universal exponential matrix (AS/NZS 4360∶1999) and integrating both background data and investigation on-site. Results It was reported that there were 6 nuclear reactors, over 10 000 radioactive sources (including useless radioactive sources ), 1 428 radiation work units and almost 11 000 radiation workers in Beijing, and about 0.3~1 million packages of radioactive materials came in or went out of Beijing annually. According to some statistics, the probability of local radiation accidents was one time per year, 67% of which resulted from radioactive sources lost/stolen, 33% from exposure to high radiation field and 11% from other factors such as abnormal transportation of radioactive materials. All of these radiation risks could be classified as accidental risks or potential risks in terms of their seriousness. Either determinate effect or stochastic effect which induced radiation health injury could be brought by the radiation risk. Furthermore, it was shown that we should pay more attention on nuclear terrorism, nuclear accident, radiation accident, as well as the accidents of radioactive sources lost/stolen which were the most serious one among 13 kinds of radiation risks. Conclusion It is necessary to take several protective measures to prevent any radiation accidents from happening during Beijing Olympic Game in 2008,because of complicated radiation factors and great difficulties in controlling radiation risks of Beijing.

对螺旋CT的检测模体及检测方法进行了调研试用,并对螺旋CT扫描轮廓线(SSP)进行了初步测试与分析.

X射线床旁拍片是一种常见的检查方法,为临床提供了大量有重要价值的影像资料.人们对辐射认识提高的同时也产生了对X射线的恐惧感,在进行床旁拍片时经常遇到受检或非受检患者的质疑或不满.因此,我们根据的实际工作状况与北京市疾病预防控制中心放射卫生防护所共同对床旁X射线检查进行了检测.

目的:调研北京地区所用的CR乳腺摄影影像质量情况,为卫生行政管理部门决策提供实测参考数据.材料与方法:在同样条件下分别用屏/片、CR摄取同一个标准乳腺模体的影像,参照美国MQSA标准,由临床专家和影像检测技术人员盲评其空间分辨率和可分辨微钙化点簇数、纤维条数及半球状肿块数.结果与讨论:富士(FUJI)公司的FCRPROFECTCS系统的影像质量和柯达(KODAK)公司最新屏/片的影像质量比较接近:空间分辨率7～8Lp/mm为屏/片影像的一半,其他三项则与屏/片影像持平.FCR PROFECT CS系统DQE较高,用屏/片摄影一半剂量摄影,临床专家已区分不出是屏/片影像还是FCRPROFECTCS系统的CR影像;所调查的其他型号CR影像质量均比屏/片系统差,可分辨微钙化点的尺寸大于0.2mm,这些类型CR不适合用于乳癌普查.

近两年CR在北京地区获得迅速普及,据不完全统计,各种型号的CR已超过100台,保守估计其拍片量约占全市常规检查拍片总量的70%.没有一台CR配备质控软件和检测模体,15台次的检测合格率为0.CR摄影条件要比以屏片系统的高,受检者和工作人员的X射线损伤大.同时,在经济利益驱使下,非正当X线检查愈演愈烈;全民剂量负担和医疗费用迅速增加.我们认为对辐射影像设备的管理策略值得反思.

1.北京城市特征及其应急反应与救援网络建设的必要性 北京是祖国的首都,政治文化中心和现代化国际大都市,每年都要举办各种类型的国际国内重大活动.

对北京市98台CT机性能进行了检测,介绍了工作的方法与遇到的问题,并对空间分辨力、低对比度分辨力和CTDI100的测量方法进行了初步的探讨,同时对所测数据作了统计分析.

<span id="ChDivSummary" name="ChDivSummary" class="abstract-text">&lt;正&gt; 本项研制工作是为解决我国急需的X射线诊断设备质量控制而开展的。主要结果和特点是:（1）研制了12种配套的检测装置,检测指标齐全,共23项。可满足X射线诊断设备的验收和状态检测的基本要求,也可用于放射诊断部门影像质量控制的稳定性检测。（2）本研制工作设计方案合理,选用了先进的加工工艺,解决了一系列工艺难点和管电压测试片盒的刻度问题。使本检测箱在测量精度、检测影像清晰度及使用方便、外形美观等方面均不低于国外同类产品的水平。1 目的和意义</span>