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1. 发明授权

US5959300A Attenuation correction in a medical imaging system using computed path lengths and attenuation values of a model attenuation medium 失效
标题翻译：使用计算的路径长度和模型衰减介质的衰减值在医学成像系统中的衰减校正
公开(公告)号：US5959300A
公开(公告)日：1999-09-28
申请号：US833684
申请日：1997-04-08
申请人： Horace H. Hines , William K. Braymer , John R. Liebig
发明人： Horace H. Hines , William K. Braymer , John R. Liebig
IPC分类号： G01T1/164 , G01T1/29 , G01T1/166
CPC分类号： G01T1/1611 , A61B6/037 , G01T1/1642 , G01T1/2985
摘要： A method of correcting for attenuation during emission imaging in a gamma camera medical imaging system. Attenuation values are determined empirically and are stored in a look-up table in a memory that is readable by the imaging system, with each attenuation value corresponding to a given thickness value. The attenuation values are computed before imaging is performed by first measuring the number of photons which pass from a transmission source through various known depths of water or another suitable model attenuator, using the same radiation source as will be used for emission imaging. For each depth, the measurement is then used to compute the actual attenuation for a thickness of the model attenuator. The attenuation is then stored as a value in the look-up table with corresponding values of attenuator thickness and is later used to correct emission data for the effects of attenuation.
摘要翻译：一种在γ照相机医学成像系统中校正发射成像期间的衰减的方法。经验确定衰减值，并存储在可由成像系统读取的存储器中的查找表中，每个衰减值对应于给定的厚度值。在通过首先使用与用于发射成像的相同的辐射源测量从透射源通过各种已知深度的水或另一合适的模型衰减器的光子的数量来执行成像之前计算衰减值。对于每个深度，然后使用测量来计算模型衰减器的厚度的实际衰减。然后将衰减作为值与衰减器厚度的对应值一起存储在查找表中，并且随后用于校正发射数据的衰减效应。

2. 发明授权

US5682036A Method and apparatus for accurately calibrating an attenuation map for emission computed tomography 失效
标题翻译：用于精确校准发射计算机断层摄影的衰减图的方法和装置
公开(公告)号：US5682036A
公开(公告)日：1997-10-28
申请号：US580843
申请日：1995-12-29
申请人： Horace H. Hines , William K. Braymer , John R. Liebig
发明人： Horace H. Hines , William K. Braymer , John R. Liebig
IPC分类号： G01T1/164 , G01T1/29 , G01T1/166
CPC分类号： G01T1/1611 , A61B6/037 , G01T1/1642 , G01T1/2985
摘要： A method of calibrating an attenuation map for use in emission imaging in a gamma camera system. The attenuation map is generated using a transmission scan of the object of interest. The map includes a number of attenuation coefficients for the object. A computer program for generating the attenuation map includes an instruction for scaling the attenuation coefficients in the map from the transmission energy level to the emission energy level using a scaling factor. The scaling factor includes an effective attenuation coefficient for water, which is determined empirically. To determine the effective attenuation coefficient, the number of photons which pass from a transmission source through known depths of water using the emission energy level is counted. The effective attenuation coefficient is computed based on a standard equation describing the attenuation of photons by an absorber. The scaling factor used by the computer program is then set based on the effective attenuation coefficient.
摘要翻译：校准用于γ照相机系统中的发射成像的衰减图的方法。使用感兴趣对象的传输扫描生成衰减图。地图包括对象的多个衰减系数。用于产生衰减映射的计算机程序包括用于使用缩放因子将图中的衰减系数从传输能级缩放到发射能级的指令。缩放因子包括水的有效衰减系数，这是经验确定的。为了确定有效衰减系数，计算从发射源通过已知深度的水使用发射能级的光子数。基于描述吸收体光子衰减的标准方程来计算有效衰减系数。然后根据有效的衰减系数设定计算机程序使用的缩放因子。

3. 发明授权

US5744802A Image generation from limited projections in positron emission tomography using multi-slice rebinning 失效
标题翻译：使用多片重组的正电子发射断层扫描中的有限投影图像生成
公开(公告)号：US5744802A
公开(公告)日：1998-04-28
申请号：US547951
申请日：1995-10-25
申请人： Gerd Muehllehner , Peter Countryman , William K. Braymer
发明人： Gerd Muehllehner , Peter Countryman , William K. Braymer
IPC分类号： G01T1/161 , G01T1/164 , G01T1/166 , G01T1/29 , G06T11/00
CPC分类号： G06T11/006 , G01T1/1648 , G01T1/2985 , G06T2211/424 , G06T2211/436 , Y10S378/901
摘要： A method of reconstructing an image in a medical imaging system comprises the steps of detecting transverse rays and oblique rays using a limited range of projection angles. The limited range of projection angles is achieved by either limiting the range of rotation of the detectors at each position along the z axis, or by causing the detectors to trace a continuous-motion helical path along the z axis. Data is then rebinned to create a stack of partially-complete sinograms corresponding to individual transverse slice images corresponding to, in the aggregate, a three-dimensional image. Because of the limited projection angles, each sinogram represents an incomplete data set. The rebinning includes, for each oblique ray, identifying among the sinograms the images intersected by the ray, and, applying to each of the sinograms associated with the images intersected by the ray an increment that is representative of the ray. A two-dimensional iterative reconstruction algorithm is applied to each partial sinogram in order to reconstruct a three-dimensional image slice-by-slice, followed or preceded by axially filtering to reduce blurring in the z direction.
摘要翻译：一种在医学成像系统中重建图像的方法包括以下步骤：使用有限的投影角度来检测横向射线和斜射线。投影角度的有限范围是通过限制沿着z轴的每个位置的检测器的旋转范围，或者通过使检测器沿Z轴追踪连续运动的螺旋路径来实现的。然后重新编码数据以产生对应于总体上对应于三维图像的各个横向切片图像的部分完整的正弦图的堆叠。由于投影角度有限，每个正弦图表示不完整的数据集。对于每个倾斜射线，重新组合包括在正弦图之间识别由射线相交的图像，并且对与由射线相交的图像相关联的每个正弦图应用代表光线的增量。将二维迭代重建算法应用于每个部分正弦图，以便逐个重建三维图像，之后或之前进行轴向滤波以减少z方向上的模糊。

4. 发明授权

US5225980A Reduction of image artifacts from support structures in tomographic imaging 失效
标题翻译：从图像成像中的支持结构中减少图像物质
公开(公告)号：US5225980A
公开(公告)日：1993-07-06
申请号：US799240
申请日：1991-11-27
申请人： Jiang Hsieh , William K. Braymer
发明人： Jiang Hsieh , William K. Braymer
IPC分类号： A61B6/03
CPC分类号： A61B6/032 , A61B6/4035 , A61B6/5258
摘要： An apparatus for reducing image artifacts caused by over-ranging or clipping of the data collected in a tomographic scan using a patient support, models the density profile of the patient support with a polynomial. Coefficients of the polynomial are stored in a look-up table according to gantry angle and used to estimate the over-range data. The estimated data is blended with the in-range data by convolving an over-range mask indicating which data is in-range and which data is over-range with a box car convolution kernel which produces a trapezoidal weighting mask. This weighting mask is multiplied by the estimated data and then summed to the in-range data to correct for the over-range portions of the data collected.

5. 发明授权

US5165100A Over-range image artifact reduction in tomographic imaging 失效
标题翻译：层析成像中超范围图像伪像减少
公开(公告)号：US5165100A
公开(公告)日：1992-11-17
申请号：US800197
申请日：1991-11-27
申请人： Jiang Hsieh , William K. Braymer , Kevin F. King , Patrick D. Kosinski
发明人： Jiang Hsieh , William K. Braymer , Kevin F. King , Patrick D. Kosinski
IPC分类号： A61B6/03 , G06T5/20 , G06T11/00
CPC分类号： G06T11/005 , G06T5/20 , G06T2211/432
摘要： An apparatus for reducing image artifacts caused by over-ranging or clipping of the data collected in a tomographic scan fits a geometric model to the in-range data of each projection. The geometric model is sized to the in-range data by summing all of the data of the projection to obtain a value of the total slice volume. This geometric model is used to compute the slope of the over-range data from the last point of in-range data and this extrapolated data is substituted for the over-range data. The correction process is implemented in pipeline form by convolving an over-range mask indicating which data is in-range and which data is over-range with a box car convolution kernel which produces a trapezoidal correction mask. This correction mask, multiplied by the uncorrected projection data provides the appropriate slope to its clipped portions.

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