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工业非胶片射线照像技术 一.射线实时成像 总被引:1,自引:1,他引:0
传统的工业胶片射线照相正受到数字射线照相的严重挑战。射线照相图像的探测器从胶片到图像增强器,从荧光体成像板到非晶硅和非晶硒成像板,再到阵列探测器,射线检测系统从硬件到软件在不断翻新,工业射线检查的效率和可靠性也在不断提高。采用与计算机结合的非胶片射线照相技术,能大大减少曝光时间,缩短检测周期,还可以完全避免由胶片冲洗引起的环境污染,而且射线照相影像便于存档、检索、远程传递和评定。本文系列介绍有关这方面的新技术。 相似文献
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本文扼要阐述了现代医学影像技术的两种新系统,计算机射线摄影CR和图像存档通讯系统PACS的开发、进展,基本原理和在临床实现应用中取得的卓越成果,总结其与传统的屏片组合X线照像相比的优点,并指出:这两种新技术可还以充分利用医疗单位原有的X线设备,庆受到广泛重视和采用。 相似文献
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工业射线照相影像质量评价(续)--射线照相灵敏度 总被引:1,自引:0,他引:1
(续上期)6射线照相灵敏度射线检测工艺的核心是射线照相影像质量,而影像质量的核心就是射线照相灵敏度。所谓射线照相灵敏度,是指在射线照相底片上可发现的自然细节——主要是缺陷最小尺寸的能力。但自然缺陷灵敏度一般很难作准确评价,因为它与被检工件的形状、尺寸、性质、位置和相对于射线束的角度等因素有关。通常多用人为的“细节”——一定尺寸的丝、孔、槽,使其置于透照区最不利的位置,以其显示的最小尺寸来代表射线照相灵敏度,并建立尽可能符合实际的相关灵敏度公式作为评价或选定射线透照工艺参数的理论依据。由前述内容得知,射线照… 相似文献
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(续上期)3射线照相清晰度如图5所示,用一束垂直于试件表面的射线透照一实际轮廓明锐的金属台阶边,理论上,理想的射线底片上将由两部分黑度组成:一部分是试件A0部分的高黑度均匀区,另一部分是0B部分的低黑度均匀区,两部分之间黑度突变,不连续,如图5中(a)所示。但实际上,底片上的黑度变化并不是突变的,试件的“阶边”影像是模糊的,影像的黑度变化如图中(b)所示。底片上黑度与相应区域之间的这一关系曲线简称为“黑度分布曲线”或“不清晰度曲线”。黑度变化的区域宽度就定义为射线照相不清晰度U。实际上,一个台阶边… 相似文献
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In industrial computed radiography, same as the other projection imaging systems, quantitative integrated information of total beam path including the object is carried by primary part of the beam. It is well known that the accuracy of the image useful data carried by the primary part degrades by scattered part of the beam. In order to have the beam path quantitative information accurately, it is essential to obtain the primary part of the total signal purely. In current study, a practical approach using localized primary modulation has been proposed to extract the primary signal. A semi-transparent beam attenuation grid was used as the beam intensity modulator. Efficiency and accuracy of the approach was practically validated through thickness measurement of metallic planar steps as an illustrative example. Simplified practical implementation and availability of the required accessories are some of advantages of the proposed approach. The results are indicative of the fact that this approach can also be applied as a new technique in thickness measurement, yielding a noticeable accuracy improvement in the most radiography methods. A procedure is included to explain the approach implementation for thickness measurement in computed radiography systems. The procedure overcomes some practical limitations and difficulties of the approach adaptation for computed radiography. 相似文献
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计算机X线摄影成像板与体模间隙效应(Groedel法)研究 总被引:1,自引:0,他引:1
目的:X线与被照体相互产生散射线,散射线因其特性会损害照片影像质量,增加被检者皮肤X线人射剂量,破坏生物细胞。对散射线必须进行制改。方法:在计算机X线摄影中增加体模与成像板的间隔,利用石蜡球,选择标定的曝光条件,测试出最佳的间距。结果:通过激试、研究、分析,证实间隔在20-30cm时,达到在高于伏摄影下,不使用法线栅,控制散射线量,验证了照片质量。结论:计算机X线摄影成像板与体模间隔效应(Groedel法)对降低散射线、提高空间分辨力,减少照射剂量。在影像医学检查中意义大,且实用。 相似文献
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本文分析了医用数字摄影(CR、DR)系统X射线辐射源空气比释动能测量值不确定度的主要来源,介绍了医用数字摄影(CR、DR)系统X射线辐射源空气比释动能测量值不确定度的评定步骤和方法,给出了评定结果。 相似文献
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医用数字摄影(CR、DR)系统X射线辐射源是疾病诊断的重要设备,X射线管电压是其计量检定中的一个重要项目,本文测量了X射线管电压的示值误差,并评定了其测量结果的不确定度,分析了不确定度来源及评定过程,最后给出测量不确定度报告。 相似文献
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计算机X线摄影(CR)系统使用的两种非银成像材料 总被引:2,自引:1,他引:1
本文简要地介绍了CR系统的特点,较系统地叙述了应用于CR系统的两种非银成像材料-IR成像板和医用干式影像胶片,分别介绍了它们的结构,成像原理,持性和应用方法。 相似文献
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The scatter-to-primary ratio (SPR), can serve as an important parameter for performing the scatter correction procedures or build up factor determination in radiography projections. In this work an experimental technique is presented based on localized primary modulation for direct SPR measurement. As illustrative examples, the SPR is measured for steel and aluminum step wedges to demonstrate the applicability of the presented technique in computed radiography. As a required parameter, the effective transmission factor of the modulator is measured using primary beam stopping concept over a calibration block. This technique has significant advantages such as a straight forward theory, simplified applicability in industrial site conditions, beam hardening consideration as well as automation possibility. The technique works by a single image acquisition, without image data loss in the interested area. 相似文献