Segmentation and quantification of materials with energy discriminating computed tomography: A phantom study
Segmentation and quantification of materials with energy discriminating computed tomography: A phantom study
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DOI：
10.1118/1.3525835
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发表时间：
2011-01-01
期刊：
影响因子：
3.8
通讯作者：
Molloi, Sabee
中科院分区：
文献类型：
--
作者：
Le, Huy Q.;Molloi, Sabee
目的：为了实验研究是否一个计算机断层扫描（CT）系统的基础上碲锌镉（CZT）探测器结合最小二乘参数估计技术可以用来分解四种不同的material.Methods：材料分解过程分为分割任务和量化任务。一个最小二乘最小化算法被用来分解材料与能量依赖的线性衰减系数的五个测量。建立了一套小视场能量鉴别CT系统。CT系统由X射线管、旋转台和CZT探测器阵列组成。CZT阵列由64个像素组成，每个像素为0.8 X 0.8 X 3 mm。在荧光透视模式下以80 kVp每帧50 ms采集图像。探测器将X射线光谱分解为22-32、33-39、40-46、47-56和57-80 keV的能量仓。由聚甲基丙烯酸甲酯（PMMA）、聚乙烯、聚甲醛、羟基磷灰石和碘构建了四个体模。三种假体由三种材料组成，其中嵌入了羟基磷灰石（50、150、250和350 mg/ml）和碘（4、8、12和16 mg/ml）造影剂。一个体模由四种材料组成，包埋有羟基磷灰石（150和350 mg/ml）和碘（8和16 mg/ml）。校准由嵌入羟基磷灰石（100、200、300、400和500 mg/ml）或碘（5、15、25、35和45 mg/ml）的PMMA体模组成。使用滤波反投影和斜坡滤波器从每个能量箱重建图像。结果：所有体模均得到了准确的分解，但在基底材料区域的部分体素识别错误。对于三种材料PMMA、聚乙烯和聚甲醛假体，羟基磷灰石/碘的平均定量误差分别为9.26/7.13%、7.73/5.58%和12.93/8.23%。四种材料的幻影的平均误差分别为15.62%和2.76%的羟基磷灰石和碘，foreign.Conclusions：校准的最小二乘最小化分解技术进行乳房成像任务的能量分辨探测器。该方法可以提供包含在诊断过程中可能有价值的相关材料的浓度的材料基础图像。c 2011年美国医学物理学家协会。[DOI：10.1118/1.3525835]
Purpose: To experimentally investigate whether a computed tomography (CT) system based on CdZnTe (CZT) detectors in conjunction with a least-squares parameter estimation technique can be used to decompose four different materials.Methods: The material decomposition process was divided into a segmentation task and a quantification task. A least-squares minimization algorithm was used to decompose materials with five measurements of the energy dependent linear attenuation coefficients. A small field-of-view energy discriminating CT system was built. The CT system consisted of an x-ray tube, a rotational stage, and an array of CZT detectors. The CZT array was composed of 64 pixels, each of which is 0.8 X 0.8 X 3 mm. Images were acquired at 80 kVp in fluoroscopic mode at 50 ms per frame. The detector resolved the x-ray spectrum into energy bins of 22-32, 33-39, 40-46, 47-56, and 57-80 keV. Four phantoms were constructed from polymethylmethacrylate (PMMA), polyethylene, polyoxymethylene, hydroxyapatite, and iodine. Three phantoms were composed of three materials with embedded hydroxyapatite (50, 150, 250, and 350 mg/ml) and iodine (4, 8, 12, and 16 mg/ml) contrast elements. One phantom was composed of four materials with embedded hydroxyapatite (150 and 350 mg/ml) and iodine (8 and 16 mg/ml). Calibrations consisted of PMMA phantoms with either hydroxyapatite (100, 200, 300, 400, and 500 mg/ml) or iodine (5, 15, 25, 35, and 45 mg/ml) embedded. Filtered backprojection and a ramp filter were used to reconstruct images from each energy bin. Material segmentation and quantification were performed and compared between different phantoms.Results: All phantoms were decomposed accurately, but some voxels in the base material regions were incorrectly identified. Average quantification errors of hydroxyapatite/iodine were 9.26/7.13%, 7.73/5.58%, and 12.93/8.23% for the three-material PMMA, polyethylene, and polyoxymethylene phantoms, respectively. The average errors for the four-material phantom were 15.62% and 2.76% for hydroxyapatite and iodine, respectively.Conclusions: The calibrated least-squares minimization technique of decomposition performed well in breast imaging tasks with an energy resolving detector. This method can provide material basis images containing concentrations of the relevant materials that can potentially be valuable in the diagnostic process. c 2011 American Association of Physicists in Medicine. [DOI: 10.1118/1.3525835]