Initial study of quasi-monochromatic X-ray beam performance for X-ray computed mammotomography
Initial study of quasi-monochromatic X-ray beam performance for X-ray computed mammotomography
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DOI：
10.1109/tns.2005.857629
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发表时间：
2005-10-01
影响因子：
1.8
通讯作者：
Bradshaw, ML
中科院分区：
文献类型：
--
作者：
McKinley, RL;Tornai, MP;Bradshaw, ML
我们评估了准单色束用于新开发的X射线锥束计算机乳房X光摄影应用的可行性、益处和操作参数。近单色X射线源用于全3D专用乳房X光摄影的价值在于，在将剂量水平维持在或低于现有双视乳房X光摄影的情况下，预期能够以非常小的衰减系数分离组织的能力得到改善。在以前的研究中，使用数字平板CSI(TI)探测器模型对一系列钨管电位、K边过滤材料、过滤器厚度和12厘米未压缩乳房进行的模拟表明，厚的稀土过滤材料可以提供最佳的图像质量。计算的优值系数包括：不同过滤条件下的病变对比度；测量的有无过滤的病变对比度；以及曝光效率(SNR2/曝光)。最初的实验是使用定制的x射线乳房X光断层扫描系统、铈箔过滤器和塑料乳房和病变组织相当的平板进行的。模拟结果表明，在管电位为50-70kVp，滤光片为Z=57-63的情况下，用改进的FOMS产生准单色X射线能谱。初步的实验测量证实了模拟结果，对比度和曝光效率的相对趋势和排序是一致的。这些研究表明，这种方法实际上可以用简单的硬件实现，并比未过滤或最小过滤的情况产生更高的曝光效率。
We evaluate the feasibility, benefits, and operating parameters of a quasimonochromatic beam for a newly developed x-ray cone beam computed mammotomography application. The value of a near monochromatic x-ray source for fully 3D dedicated mammotomography is the expected improved ability to separate tissues with very small differences in attenuation coefficients while maintaining dose levels at or below that of existing dual view mammography. In previous studies, simulations for a range of tungsten tube potentials, K-edge filter materials, filter thicknesses, and a 12 cm uncompressed breast, with a digital flat-panel CsI(TI) detector model, indicated that thick, rare earth filter materials may provide optimized image quality. Figures of merit computed included: lesion contrast under different filtering conditions; ratio of measured lesion contrast with and without filtering; and exposure efficiency (SNR2/exposure). Initial experiments are performed with a custom built x-ray mammotomography system, cerium foil filters, and plastic breast and lesion tissue-equivalent slabs. Simulation results showed that tube potentials of 50-70 kVp with filters of Z = 57-63 yielded quasimonochromatic x-ray spectra with improved FOMs. Initial experimental measurements corroborate simulation results in that, relative trends and rank order of contrast ratios and exposure efficiency were in agreement. These studies show that this approach can be implemented practically with simple hardware and yield improved exposure efficiency versus the unfiltered or minimally filtered case.