共查询到17条相似文献,搜索用时 203 毫秒
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文章基于EN 12543标准的边界法原理,提出了一种X射线管射线束不同张角处有效焦点尺寸测量的方法——圆柱法,采用双钨合金圆柱、像素100 μm的面阵探测器、平移和旋转机构对COMET公司的MXR 225HP/11工业X射线管大、小焦点进行测量。提出了一种测量X射线源焦点到平移旋转机构的距离及射线束不同张角处位置参数的方法。测量结果表明,该方法不仅可方便地测量焦点尺寸,而且能测量射线束张角范围内焦点尺寸的变化,并对其变化规律进行研究,这将对X射线管的焦点设计及其性能评价提供参考。 相似文献
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为表征微焦点射线机的焦点特性,采用刀口工具法进行了焦点尺寸的测试分析。采集了刀口工具法的放大影像,提取出特定透照条件下的不清晰度曲线,利用Klasens和Morgan定量准则确定了不清晰度数值进而计算出焦点尺寸,并使用双线型像质计、楔形线对卡对焦点尺寸的测试结果进行了验证分析。结果表明,在相同电压下测得的射线机焦点尺寸与管电流间近似符合二次多项式关系,刀口工具法测量结果与双线型像质计、楔形线对卡的图像特征相吻合。基于刀口工具法能可靠地对微焦点射线机的焦点尺寸进行测量,但在分析不清晰度曲线特征时需注意定量准则的适用性,而基于Morgan定量准则能给出更为合理的测量结果。 相似文献
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《核技术》2015,(11)
射线源焦点的大小与形状对射线检测图像质量有重要的影响,但在射线检测中却很少对射线源焦点进行实测,这不利于准确控制射线检测图像质量。对射线源焦点的测量方法进行对比试验分析,以获得对射线源焦点进行评估的有效便捷方法。分别应用小孔成像板、星形测试卡、双线型像质计(Image quality indicator,IQI)等测试体,对工业应用的便携式X射线机进行了焦点尺寸测量。用星形测试卡、双线型像质计所测算的焦点尺寸一致性较好,但较之小孔成像的测量结果却存在较大偏差。实际检测时射线机焦点大小可能与标称值明显不同,有必要对射线焦点特性进行及时评价;双线型像质计可一定程度上代替星形测试卡的使用,便捷地实现图像不清晰度的测量、射线源焦点尺寸的评估。 相似文献
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D-T中子发生器作为高能中子源,已用于特种核材料的有源探测技术中,利用时间符合法可实现被测物体的多模式成像,而中子源束斑尺寸是影响成像位置分辨的一个重要的因素。因此,结合D-T反应的特点和实际应用环境,开发了n-α关联符合测量确定中子源束斑尺寸的方法。利用该方法对小型移动中子发生器的束斑尺寸进行了测量,获得的束斑尺寸为(2.8±0.9) mm,与用CCD相机直接观测得到的约3 mm的测量结果一致,证明了该方法测量束斑尺寸的可行性。该方法也可用于辅助D-T中子源调束和关联粒子成像实验过程中的束斑监测。 相似文献
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《核电子学与探测技术》2017,(11)
针对传统锥束CT重建存在大量冗余计算的问题,建立了锥束CT图像矩形包围盒快速重建方法。该方法将重建空间限定为三维矩形包围盒,大大减少了待重建体素的数量,接着将Z线优先算法反投影部分的计算移植到GPU上加速重建。实验结果表明:该方法显著提高了锥束CT图像的重建速度,可推广应用于采用类似算法重建的CT系统。 相似文献
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提出了评定带周向缺陷塑性失稳失效的一种新方法-名义应力比法,并详细说明该方法的优点和基本思路,与ASME规范许可缺陷尺寸表法相比,该方法更实用。 相似文献
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利用多毛细管准直器测量X射线光源焦斑尺寸 总被引:1,自引:1,他引:0
设计了一种测量X射线光源焦斑尺寸的方法:多毛细管准直器法。整体玻璃毛细管X射线准直器是由数105根内径为几微米的单玻璃毛细管组成的X射线光学器件,X射线光源发出的发散X射线光束被多毛细管准直器约束后变为准平行束。准平行束的截面直径是X射线光源焦斑直径的函数,通过测量准平行束不同位置处的截面直径,利用线性拟合可得到X射线光源的焦斑直径。分别利用多毛细管准直器法和常用的小孔成像法测量了同一微焦斑X射线光源的焦斑直径,测量结果分别为60.8和59.4μm。多毛细管准直器法对焦斑直径在亚微米量级或更小X射线源的焦斑尺寸测量中将显示出更多的优势。 相似文献
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ZHANG Kai HOU Long CHEN Hongtao BAO Jie SU Ming RUAN Nianshou ZHAO Fang 《原子能科学技术》1959,54(12):2289-2295
As a high-energy neutron source, the D-T neutron generator has been used in the active detection technology of special nuclear materials. The time coincidence method can be used to achieve multi-mode imaging of the measured object, and the beam spot size of the neutron source is a very important factor that affects the imaging position resolution. Therefore, combined with the characteristics of D-T reaction and practical application environment, a method for n-α correlation coincidence measurement to determine the beam spot size of neutron source was developed. This method was used to measure the beam spot size of a small mobile neutron generator. The beam spot size obtained is (2.8±0.9) mm, which is consistent with the measurement result of about 3 mm obtained by direct observation with CCD camera, which proves that this method is feasible. This method can also be used to assist D-T neutron source beam tuning and beam spot size monitoring in associated particle imaging experiments. 相似文献
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A self-magnetic pinch diode(SMPD) integrating an anode foil-reinforced electron beam pinch focus and a small high-dose x-ray spot output was designed and optimized. An x-ray focal spot measuring system was developed in accordance with the principle of pinhole imaging. The designed SMPD and the corresponding measuring system were tested under ~MV, with 1.75?×?2 mm~2 oval x-ray spots(AWE defined) and forward directed dose 1.6 rad at 1 m. Results confirmed that the anode foil can significantly strengthen the electron beam pinch focus, and the focal spot measuring system can collect clear focal spot images. This finding indicated that the principle and method are feasible. 相似文献
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区别于大型加速器上对于束斑的定义与计算,医用电子直线加速器的束斑会影响剂量的X辐射分布(Profile)的半影区,从而影响放疗设备的治疗精度,对它的研究侧重点也不同于其它类型的加速器。基于这个原因,针对目前医用电子直线加速器尤其是国内医用电子直线加速器对电子束束斑计算与测量数据不够的问题,从束斑的理论计算出发,归纳了两种方法,并进行了对比研究。在理论研究的基础上,对上海联影医疗有限公司的6 Me V医用电子直线加速器的束斑进行了实验测量,采用两种高斯分布叠加拟合实验数据以得到较好的精度,对实验中的系统误差进行了分析,与理论计算较为吻合。 相似文献
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Jun Hasegawa Sarawut JaiyenYoshiyuki Oguri 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2011,269(24):3087-3090
The performance of a compact micro-PIXE system using a tapered glass capillary for beam focusing was examined with the help of Monte-Carlo simulations. The effective beam spot size was evaluated by an edge-scanning method and a two-dimensional element mapping was successfully demonstrated by using a copper fine-mesh target. The spatially resolved energy-spectrum measurement revealed that even protons scattered at the inner wall of the capillary have kinetic energies enough to induce the X-ray emission in the target. Monte-Carlo simulations showed that the beam-focusing factors of the capillaries used in this study are about 1.7. The uniformity of the beam does not depend so much on the distance from the capillary outlet, but the beam radius was found to be twice larger than its original size even at 1 mm from the capillary outlet, which was consistent with the effective beam spot size measurement. 相似文献