How to improve x-ray scattering techniques to quantify bone mineral density using spectroscopy.
How to improve x-ray scattering techniques to quantify bone mineral density using spectroscopy.
复制标题
如何改进 X 射线散射技术，利用光谱学量化骨矿物质密度。
DOI：
10.1118/1.3687162
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发表时间：
2012
期刊：
影响因子：
3.8
通讯作者：
Ganezer,K
中科院分区：
文献类型：
--
作者：
Krmar,M;Ganezer,K
目的：本研究的目的是开发一种测量骨矿物质密度 (BMD) 的新诊断技术，以评估骨质疏松症，该技术改进了 20 世纪 80 年代首次开发的相干康普顿散射比 (CCSR) 方法。为了帮助作者实现这些目标，他们确定并研究了 CCSR 的两个新指数，即前向散射与后向散射 (FS-BS) 和前向散射与透射 (FS-T) 比率。他们认为，在小角度下，这两个参数可以提供实用的体内 BMD 测定，从而克服过去 CCSR 系统的局限性，包括高辐射剂量、成本和检查持续时间。 方法：在之前的 CCSR 研究中，采用半衰期较长的高活度放射源（通常为 241Am）和昂贵且笨重的低温 HPGe 探测器进行体内和体外测量。为了使该技术更适合临床应用，本文研究了使用标准诊断 X 射线管生成连续光谱的可能性。本研究使用相对便宜的非低温 CdTe 或 NaI 探测器收集了来自小梁骨模拟体模的散射辐射，这些矿物质密度涵盖体内 BMD 正常范围。结果：初步结果表明，CCSR 的修改版本可以使用具有两种变化（FS-BS 和 FS-T 比率）连续光谱的诊断 X 射线管成功应用于小梁骨评估。测量FS-BS时，必须收集前向和后向的强度谱，而FS-T只需要40 keV以上能量区域的散射和透射（T）谱的积分强度。对于这两种方法，都需要小于或等于 15° 的前向散射角和大于或等于 (165°= 180° − 15°) 的后向散射角。结论：作者确定 FS-T 对 BMD 的变化比单独的透射或吸收更敏感，并且 FS-BS 方法在对路径相关衰减进行校正后，可以产生散射介质平均原子序数的绝对测量。由于这项研究确定 FS-T 比率在广泛的能量区域内与入射能量无关，因此可以使用廉价的积分光子探测器将 FS-T 应用于骨密度测量。作者认为，通过用 X 射线管代替放射性核素源，用单个固态 CdTe、NaI 或硅探测器或探测器环形阵列代替低温冷却 HPGe 探测器（如本研究中所述），可以克服 CCSR 过去在高辐射暴露、成本和持续时间以及缺乏便利性方面的困难，并且 CCSR 最终可能在临床环境中流行。
Purpose:The purpose of this study was to develop a new diagnostic technique for measuring bone mineral density (BMD) for the assessment of osteoporosis, which improves upon the coherent to Compton scattering ratio (CCSR) method, which was first developed in the 1980s. To help the authors achieve these goals, they have identified and studied two new indices for CCSR, the forward scattered to backward scattered (FS‐BS) and the forward scattered to transmitted (FS‐T) ratios. They believe that, at small angles, these two parameters can offer a practicalin vivodetermination of BMD that can be used to overcome the limitations of past CCSR systems, including high radiation dosages, costs, and examination durations.Methods:In previous CCSR studies, a high‐activity radioactive source with a long half‐live (usually241Am) and an expensive and bulky cryogenic HPGe detector were applied to bothin vivoandin vitromeasurements. To make this technique more suitable for clinical applications, the possibility of using a standard diagnostic x‐ray tube generating a continuous spectrum was investigated in this paper. Scattered radiation from trabecular bone‐simulating phantoms containing various mineral densities that span the normal range ofin vivoBMD was collected in this study using relatively inexpensive noncryogenic CdTe or NaI detectors.Results:The initial results demonstrate that a modified version of CCSR can be successfully applied to trabecular bone assessment using a diagnostic x‐ray tube with a continuous spectrum in two variations, the FS‐BS and the FS‐T ratio. When FS‐BS is measured, intensity spectra in the forward and backward directions must be collected while FS‐T requires only the integral intensity of the scattered and transmitted (T) spectra in the energy region above 40 keV. For both of these methods, forward scattering angles less than or equal to 15° and backward scattering angles greater than or equal to (165°= 180° − 15°) are needed.Conclusions:The authors determined that FS‐T is more sensitive to changes in BMD than transmission or absorption alone and that the FS‐BS method can yield an absolute measurement of the mean atomic number of the scattering medium, after a correction for path‐dependent attenuation. Since this study determined that the FS‐T ratio is independent of the incident energy over a broad energy region, it will be possible to apply FS‐T to bone densitometry using inexpensive integral photon detectors. The authors believe that, by replacing the radionuclide source with an x‐ray tube and the cryogenically cooled HPGe detector with a single solid state CdTe, NaI, or silicon detector or an annular array of detectors, as suggested in this study, the past difficulties of CCSR concerning high radiation exposure, costs, and durations as well as lack of convenience can be overcome and that CCSR could eventually become popular in clinical settings.