z尺寸和厚度（0018,0050）的间距值在dicom系列中有何不同？ [英] How are the spacing value of the z dimension and thickness (0018, 0050) different in dicom series?

问题描述

我一直在研究一些dicom系列，发现厚度属性和itkimage.GetSpacing（）[2]值并不总是一致的。

I've been studying some dicom series and find that the thickness attribute and the itkimage.GetSpacing()[2] value are not always consistent.

例如在dcm文件中编码的厚度（0018,0050）值 1.5 mm，但z轴上指示simpleITK的相应间距 1.00 。那么我应该用什么值来表示z轴上相邻体素中心之间的物理距离？如果它们是不同的东西，那么间距实际意味着什么？

For example the thickness (0018, 0050) value encoded in the dcm file is 1.5 mm but the corresponding spacing indicated simpleITK on z axis is 1.00. Then what value should I use to indicate the physical distance between adjacent voxel centers on the z axis? If they are different things then What do spacings actually mean?

我在python中检索厚度和间距值，如下所示：

I retrieve thickness and spacing values in python like this:

//thickness using dicom
thickness = dicom.read_file(dcm_file)[0x0018, 0x0050].value

//spacing using simpleITK
reader = sitk.ImageSeriesReader()
dicom_files = reader.GetGDCMSeriesFileNames(dicom_dir)
reader.SetFileNames(dicom_names)
itkImage= rader.Execute

spacing_x, spacing_y, spacing_z = itkImage.GetSpacing()

我一直在搜索文档但是没有'找到了类似答案的东西。谢谢！

I've been searching in the docs but haven't found something like an answer yet. Thanks!

====== Update1 ======

====== Update1 ======

我查了一下图像位置（患者）（0020,0032）值，每片切片确实距离1mm。那么厚度是什么意思？

I've checked the Image Position(Patient) (0020,0032) value and they are indeed 1mm away per slice. Then What leaves thickness mean?

推荐答案

扫描仪可以测量的最小切片厚度。并且相邻切片的测量位置之间存在距离。在创建图像时，扫描仪不必测量恰好一个厚度的下一个切片，它可以更少（使一些测量重叠）或更多（在测量中产生一些间隙）。对于相邻的体素中心，您需要间距。厚度是额外的信息，通常价值不大。

There is a minimum slice thickness which a scanner can measure. And there is the distance between measurement positions for adjacent slices. And when creating an image, the scanner does not have to measure the next slice exactly one thickness away, it can be less (making some measurement overlap) or more (creating some gaps in measurements). For adjacent voxel centers, you want spacing. Thickness is extra information, usually of little value.

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