X射线计算机断层摄影(CT)受检者剂量检测方法的研究

本文介绍了目前国际上两种通用的ＣＴ受检者剂量的表示方法和检测方法。通常用多层扫描平均剂量（ＭＳＡＤ）或ＣＴ剂量指数（ＣＴＤＩ）来表示ＣＴ受检者的剂量；用ＣＴ标准电离室（笔形电离室）或热释光剂量计（ＴＬＤ）进行检测。通过实验和数学模拟方法，找出了ＭＳＡＤ与ＣＴＤＩ之间和不同方法检测结果之间的关系，为今后推广使用这两种检测方法进行ＣＴ受检者剂量监测和推广使用国际电离辐射防护与辐射源安全基本标准（ＩＢＳＳ）推荐的ＣＴ受检者剂量指导水平打下技术基础。     

X射线计算机断层摄影（CT）受检地剂量检测方法的研究

本文介绍了目前国际上两种通用的ＣＴ受检者剂量的表示方法和检测方法，通常用多层扫描平均剂量（ＭＳＡＤ）或ＣＴ剂量指数ＣＴＤＩ来表示ＣＴ受检者的剂量；用ＣＴ标准电离室（笔形电离室）或热释光剂量计（ＴＬＤ）进行检测，通过实验和数学模拟方法，找出ＭＳＡＤ与ＣＴＤＩ之间和不同方法检测结果之间的关系，为今后推广使用这种检测方法进行了ＣＴ受检者剂量监测和推广使用国际电离辐射防护与辐射源安全基本标准（ＩＢＳＳ）推     

SPECT脑血流灌注显像应用于脑血管疾病

７０例脑血管疾病患者（脑梗塞、ＴＩＡ、ＶＢＩ）行＾９９ｍＴｃ－ＥＣＤ ＳＰＥＣＴ脑血流灌注显像，并与ＣＴ、ＭＲＩ对照，结果ＳＥＰＣＴ诊断脑血管病的阳性率为９０％。ＣＴ为８８．２％（４５／５１），ＭＲＩ为９０％（２７／３１）。脑梗塞５５例中５１例ｒＣＢＦ图像上出现血流灌注减低区，４例发现交叉性小脑神经机能失联络证。诊断ＴＩＡ、ＶＢＩ的阳性率为７５％。ＳＰＥＣＴｒＣＢＦ显像发现病灶较ＣＴ、ＭＲＩ多；可     

^99mTc（V）—DMSA及^99mTc—MIBI肺显像诊断原发性肺癌的应用研究

对３０例原发性肺癌患者分别应用＾９９ｍＴｃ（ｖ）－ＤＭＳＡ及＾９９ｍＴｃ－ＭＩＢＩ显像。结果表明：＾９９ｍＴｃ９Ｖ）－ＤＭＳＡ，＾９９ｍＴｃ－ＭＩＢＩ敏感度分别为９０％，７６．７％。两者结合显像阳性率为９６．７％。鳞状上皮细胞癌对＾９９ｍＴｃ（Ｖ）－ＤＭＳＡ及＾９９ｍＴｃ（Ｖ）－ＤＭＳＡ，＾９９ｍＴｃ－ＭＩＢＩ摄取程度比其它类型的肺癌高。     

MEASUREMENTS OF TOTAL CROSS SECTIONS FOR K－SHELL IONIZATION BY ELECTRON BOMBARDMENT

ＭＥＡＳＵＲＥＭＥＮＴＳＯＦＴＯＴＡＬＣＲＯＳＳＳＥＣＴＩＯＮＳＦＯＲＫ－ＳＨＥＬＬＩＯＮＩＺＡＴＩＯＮＢＹＥＬＥＣＴＲＯＮＢＯＭＢＡＲＤＭＥＮＴＬｉＪｉｎｇｗｅｎ（李景文）；ＤｏｎｇＺｈｉｑｉａｎｇ（董志强）；ＺｅｎｇＸｉａｎｔａｎｇ（曾宪堂），Ｈ...     

头部CT扫描时受检者剂量研究

应用热释光剂量和头部CT剂量监测模体,在日立W-1000型机器上测定了模体中心和距体表1cm处,单层和多层扫描时的剂量分布。给出了单层扫描时,散射线所致剂量与扫描中心距离的拟合方程,分析了用不同积分区间计算CT剂量指数（CTDI）时对结果的影响。为今后进行广泛的CT受检者的剂量监测,推广使用国际电离辐射防护和辐射源安全基本标准（IBSS）推荐的CT受检者剂量指导水平提供统一标准。并对CT剂量监测中一些值得关注的问题进行探讨。     

~(99m)Tc(Ⅴ)-DMSA 及 ~(99m)Tc-MIBI 肺显像诊断原发性肺癌的应用研究

对３０例原发性肺癌患者分别应用９９ｍＴｃ（Ⅴ）－ＤＭＳＡ及９９ｍＴｃ－ＭＩＢＩ显像。结果表明：９９ｍＴｃ（Ⅴ）－ＤＭＳＡ、９９ｍＴｃ－ＭＩＢＩ敏感度分别为９０％、７６．７％。两者结合显像阳性率为９６．７％。鳞状上皮细胞癌对９９ｍＴｃ（Ⅴ）－ＤＭＳＡ及９９ｍＴｃ－ＭＩＢＩ摄取程度比其它类型的肺癌高。     

PIXE AND IXX ANALYSIS OF MUSEUM PAPERLIKE OBJECT

ＰＩＸＥＡＮＤＩＸＸＡＮＡＬＹＳＩＳＯＦＭＵＳＥＵＭＰＡＰＥＲＬＩＫＥＯＢＪＥＣＴＳＷｕＸｉａｎｋａｎｇ（邬显慷）（ＩｎｓｔｉｔｕｔｅｏｆＮｕｃｌｅａｒＲｅｓｅａｒｃｈ，ｔｈｅＣｈｉｎｅｓｅＡｃａｄｅｍｙｏｆＳｃｉｅｎｃｅｓ，Ｓｈａｎｇａｉ２０１８０...     

ASSESSMENT OF COLLECTIVE DOSE FOR TRAVELLERS BY WATERS

ＡＳＳＥＳＳＭＥＮＴＯＦＣＯＬＬＥＣＴＩＶＥＤＯＳＥＦＯＲＴＲＡＶＥＬＬＥＲＳＢＹＷＡＴＥＲＳＹｕｅＱｉｎｇｙｕ（岳清宇）；ＪｉａｎｇＰｉｎｓ（姜萍）ａｎｄＪｉｎＨｕａ（金花）（ＣｈｉｎａＩｎｓｔｉｔｕｔｅｏｆＡｔｏｍｉｃＥｎｅｒｇｙ，Ｂｅｉｊｉｎｇ...     

CONCLUSION OF INTERNATIONAL SYMPOSIUM ON NUCLEAR ENERGY AND THE ENVIRONMENT AT BEIJIN ON 14～18 OCT.1996

ＣＯＮＣＬＵＳＩＯＮＯＦＩＮＴＥＲＮＡＴＩＯＮＡＬＳＹＭＰＯＳＩＵＭＯＮＮＵＣＬＥＡＲＥＮＥＲＧＹＡＮＤＴＨＥＥＮＶＩＲＯＮＭＥＮＴＡＴＢＥＩＪＩＮＯＮ１４～１８ＯＣＴ．１９９６Ｂ．Ｇ．Ｂｅｎｎｅｔ（ＵＮＳＣＥＡＲ）Ｗｅｈａｖｅｃｏｍｅｔｏｔｈｅｅｎ...     

利用蒙特卡罗建模及估算儿童X-CT检查受照剂量

在儿科X射线-CT检查迅速增加的当下,尤其对电离辐射敏感的儿童,其所致医疗照射剂量的评估是十分重要和迫切的课题。本文结合已建立的1岁儿童体素体模,利用蒙特卡罗技术建立扫描模型,进行CT检查所致儿童受检者的医疗照射剂量估算。建立了CT单层轴向扫描时对1岁儿童36个器官或组织所产生医疗照射剂量的数据库,利用该数据库,可快速估算1岁儿童受检者接受CT扫描时的医疗照射剂量。并与同样扫描条件下的实验测量值进行了比较,结果显示二者相对偏差在25%以内。     

Conversion from Tooth Enamel Dose to Organ Doses for Electron Spin Resonance Dosimetry

Conversion from tooth enamel dose to organ doses was analyzed to establish a method of retrospective individual dose assessment against external photon exposure by electron spin resonance (ESR) dosimetry. Dose to tooth enamel was obtained by Monte Carlo calculations using a modified MIRD-type phantom with a teeth part. The calculated tooth enamel doses were verified by measurements with thermo-luminescence dosimeters inserted in a physical head phantom. Energy and angular dependences of tooth enamel dose were compared with those of other organ doses. Additional Monte Carlo calculations were performed to study the effect of human model on the tooth enamel dose with a voxel-type phantom, which was based on computed tomography images of the physical phantom. The data derived with the modified MIRD-type phantom were applied to convert from tooth enamel dose to organ doses against external photon exposure in a hypothesized field, where scattered radiation was taken into account. The results indicated that energy distribution of photons incident to a human body is required to evaluate precisely an individual dose based on ESR dosimetry for teeth.     

Superpett 3000 time-of-flight PET tomograph: optimization offactors affecting quantitation

In positron-emission tomography (PET), to certify that the observed radioactivity in the organ of interest represents the true underlying radioactivity concentration, an experimental/theoretical treatment of factors such as scatter, randoms, reconstruction parameters, recovery coefficients and the cross-calibration procedure is required. Dual isotope experiments used to check the overall tomograph performance are described. It is found that the inclusion of a real-time calibration tube standard in the tomograph field-of-view during scanning compensates for any temporal variation in the machine sensitivity and provides a built-in dead time correction. Reconstruction parameters and recovery coefficients were optimized through phantom experiments. It is shown that results similar to other head and whole body scanners have been achieved     

CT-W_4(日立)头部扫描时患者的剂量分布

本文应用热释光剂量计和人体模型,测定了 CT-W_4(日立)全身扫描机进行了单层和20层头部扫描时患者脑组织的照射量分布、最大体表照射量、器官剂量和有效剂量当量;导出了头部扫描时患者眼晶体和甲状腺剂量的估算公式。     

The effect of pitch and collimation on radiation dose in spiral CT

1 Introduction Spiral computed tomography (CT) was intro- duced in clinical practice in 1980s. Its distinctive characteristic is continuous data acquisition and con- tinuous tube rotation with high speed while simulta- neously translating the patient through the gantry.[1] Owing to these functions the spiral CT possesses the ability to scan an entire organ volume within a single breathhold. Thus, the anatomical section is contiguous and therefore the reliable demonstration of small le- sions…     

A way forward for the development of an exposure computational model to computed tomography dosimetry

A way forward for the development of an exposure computational model to computed tomography dosimetry has been presented. In this way, an exposure computational model (ECM) for computed tomography (CT) dosimetry has been developed and validated through comparison with experimental results. For the development of the ECM, X-ray spectra generator codes have been evaluated and the head bow tie filter has been modelled through a mathematical equation. EGS4 and EGSnrc have been used for simulating the radiation transport by the ECM. Geometrical phantoms, commonly used in CT dosimetry, have been modelled by IDN software. MAX06 has also been used to simulate an adult male patient submitted for CT examinations. The evaluation of the X-ray spectra generator codes in CT dosimetry showed dependence with tube filtration (or HVL value). More generally, with the increment of total filtration (or HVL value) the X-raytbc becomes the best X-ray spectra generator code for CT dosimetry. The EGSnrc/X-raytbc combination has calculated C_100,c in better concordance with C_100,c measured in two different CT scanners. For a Toshiba CT scanner, the average percentage difference between the calculated C_100,c values and measured C_100,c values was 8.2%. Whilst for a GE CT scanner, the average percentage difference was 10.4%. By the measurements of air kerma through a prototype head bow tie filter a third-order exponential decay equation was found. C_100,c and C_100,p values calculated by the ECM are in good agreement with values measured at a specific CT scanner. A maximum percentage difference of 2% has been found in the PMMA CT head phantoms, demonstrating effective modelling of the head bow tie filter by the equation. The absorbed and effective doses calculated by the ECM developed in this work have been compared to those calculated by the ECM of Jones and Shrimpton for an adult male patient. For a head examination the absorbed dose values calculated by the ECM developed by Jones and Shrimpton overestimates up to three times the absorbed dose to brain compared to the ECM developed in this work. The effective dose calculated by the ECM of Jones and Shrimpton was 26% greater than effective dose calculated by the ECM developed in this work.     

胸部X射线CT扫描中的放射防护最优化

X射线螺旋CT机不同扫描条件下,用有机玻璃均匀模体测量多层扫描的CT剂量指数值,用均匀水模体测量CT值的均匀性及其噪声。比较了不同扫描条件下,患者肺部肿块影及片状影的CT图像质量。结果表明：曝露量为40、25、7．5mAs时的CT剂量指数值分别不超过曝露量为115mAs时的40％、30％和15％。本文用CT扫描“优化因子”作为图像质量、病人所受剂量的综合评价指标,实现了CT扫描条件优化的定量分析。虽然,随X射线曝露量减少,均匀模体断层内CT值噪声增加、正常图像百分率下降,但从图像质量、病人剂量综合考虑,X射线胸部CT扫描的曝露量宜取25mAs。     

Managing patient dose in multi-detector computed tomography(MDCT). ICRP Publication 102

Computed tomography (CT) technology has changed considerably in recent years with the introduction of increasing numbers of multiple detector arrays. There are several parameters specific to multi-detector computed tomography (MDCT) scanners that increase or decrease patient dose systematically compared to older single detector computed tomography (SDCT) scanners. This document briefly reviews the MDCT technology, radiation dose in MDCT, including differences from SDCT and factors that affect dose, radiation risks, and the responsibilities for patient dose management. The document recommends that users need to understand the relationship between patient dose and image quality and be aware that image quality in CT is often higher than that necessary for diagnostic confidence. Automatic exposure control (AEC) does not totally free the operator from selection of scan parameters, and awareness of individual systems is important. Scanning protocols cannot simply be transferred between scanners from different manufacturers and should be determined for each MDCT. If the image quality is appropriately specified by the user, and suited to the clinical task, there will be a reduction in patient dose for most patients. Understanding of some parameters is not intuitive and the selection of image quality parameter values in AEC systems is not straightforward. Examples of some clinical situation shave been included to demonstrate dose management, e.g. CT examinations of the chest, the heart for coronary calcium quantification and non-invasive coronary angiography, colonography, the urinary tract, children, pregnant patients, trauma cases, and CT guided interventions. CT is increasingly being used to replace conventional x-ray studies and it is important that patient dose is given careful consideration, particularly with repeated or multiple examinations.