来自Python的GDCM ImageRegionReader

Question

我正在尝试使用GDCM从dicom文件中只读取一个切片。数据是多片dicom。

r = gdcm.ImageRegionReader()
r.SetFileName( 'test.dcm' )
r.ReadInformation()

image = r.GetImage()
dimensions = image.GetDimensions()
pixelformat = image.GetPixelFormat()
pixelsize = pixelformat.GetPixelSize()

bytes_per_slice = dimensions[0] * dimensions[1] * pixelsize

box = gdcm.BoxRegion()
box.SetDomain(0, dimensions[0] - 1, 0, dimensions[1] - 1, 1, 1)

r.SetRegion(box)

这一切都可以工作，但是我如何读取像素呢？

nptypes = {gdcm.PixelFormat.UINT8  :numpy.int8,
            gdcm.PixelFormat.INT8   :numpy.uint8,
            gdcm.PixelFormat.UINT16 :numpy.uint16,
            gdcm.PixelFormat.INT16  :numpy.int16,
            gdcm.PixelFormat.UINT32 :numpy.uint32,
            gdcm.PixelFormat.INT32  :numpy.int32,
            gdcm.PixelFormat.FLOAT32:numpy.float32,
            gdcm.PixelFormat.FLOAT64:numpy.float64 }

arr = np.array(bytes_per_slice, dtype=pixelformat.GetScalarType())
# also tried np.uint8 as dtype
buffer = np.getbuffer(arr)


#
# now this fails
#
r.ReadIntoBuffer(buffer, bytes_per_slice)
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-95-a8022420e1c1> in <module>()
----> 1 r.ReadIntoBuffer(buffer, bytes_per_slice)

lib/python2.7/site-packages/gdcmswig.pyc in ReadIntoBuffer(self, inreadbuffer, buflen)
  20678         Read into buffer: false upon error
  20679         """
> 20680         return _gdcmswig.ImageRegionReader_ReadIntoBuffer(self, inreadbuffer, buflen)
  20681 
  20682 ImageRegionReader_swigregister = _gdcmswig.ImageRegionReader_swigregister

TypeError: in method 'ImageRegionReader_ReadIntoBuffer', argument 2 of type 'char *'

如何传递numpy缓冲区？我尝试了一些ctype的东西，但它们都不起作用。