[Insight-users] Incorrect voxel size usign GetSpacing()

[Jafari, Kourosh]

Dear ITK users,

I use itk::ImageFileReader to read a 3-D cone beam CT image in dicom format (in a single file) and I get incorrect voxel size. The correct voxel size is 0.32x0.32x0.32 mm3 but it gives me a wrong voxel size of 1x1x0.32 mm3. MRIcro reads and displays the file correctly. Can anyone help?

Here are some main lines of the code (I have not included the whole code) that I use to display the voxel size:

typedef  short  int   PixelType;
typedef itk::Image< PixelType, Dimension >  ImageType;
typedef itk::ImageFileReader< ImageType  > ImageReaderType;

ImageReaderType::Pointer ImageReader = ImageReaderType::New();
ImageType::Pointer image = ImageReader->GetOutput();
....

const ImageType::SpacingType& Size =image->GetSpacing();
std::cout << Size.GetElement(0)<< std::endl;
std::cout << Size.GetElement(1) << std::endl;
std::cout << Size.GetElement(2) << std::endl;





Also, I have run DicomImageReadPrintTags to see the tags. Here is what I get (I have modified some parts to protect identity):



(0002|0000) Group Length = 214
(0002|0001) File Meta Information Version = AAE=
(0002|0002) Media Storage SOP Class UID = 1.2.840.10008.5.1.4.1.1.2.1
(0002|0003) Media Storage SOP Instance UID = 2.16.840.1.113669.632.10.20100303.160809437.260454.8
(0002|0010) Transfer Syntax UID = 1.2.840.10008.1.2.1
(0002|0012) Implementation Class UID = 2.16.840.1.113669.632.10.99.2
(0002|0013) Implementation Version Name = ROMEXIS 001
(0002|0016) Source Application Entity Title = ROMEXIS_1
(0008|0005) Specific Character Set = ISO_IR 100
(0008|0008) Image Type = ORIGINAL\PRIMARY
(0008|0012) Instance Creation Date = 20100308
(0008|0013) Instance Creation Time = 164732
(0008|0016) SOP Class UID = 1.2.840.10008.5.1.4.1.1.2.1
(0008|0018) SOP Instance UID = 2.16.840.1.113669.632.10.20100303.160809437.260454.8
(0008|0020) Study Date = 20100303
(0008|0021) Series Date = 20100303
(0008|0023) Content Date = 20100303
(0008|002a) Acquisition Datetime = 20100303160809.000000
(0008|0030) Study Time = 160809
(0008|0031) Series Time = 160809
(0008|0033) Content Time = 160809
(0008|0050) Accession Number =
(0008|0060) Modality = CT
(0008|0070) Manufacturer = Planmeca
(0008|0080) Institution Name = Auburn Clinic
(0008|0090) Referring Physician's Name =
(0008|1010) Station Name = 1
(0008|1040) Institutional Department Name = Max Facial Xray Dept
(0008|1090) Manufacturer's Model Name = ProMax
(0008|9205) Pixel Presentation = MONOCHROME
(0008|9206) Volumetric Properties = VOLUME
(0008|9207) Volume Based Calculation Technique = NONE
(0010|0010) Patient's Name = Dixson^Dave (m-43y) 88/12/12^^Dr.^
(0010|0020) Patient ID = 3224
(0010|0030) Patient's Birth Date =
(0010|0040) Patient's Sex =
(0018|0015) Body Part Examined = HEAD
(0018|0050) Slice Thickness = 0.32
(0018|0060) KVP = 84
(0018|1000) Device Serial Number = TDX260454
(0018|1020) Software Version(s) = 1.21.7.0.r
(0018|1150) Exposure Time = 12140
(0018|1151) X-ray Tube Current = 14
(0018|115e) Image Area Dose Product = 874.4517211914062
(0018|5100) Patient Position = HFS
(0018|700a) Detector ID = TDX260454
(0018|9073) Acquisition Duration = Ház?®G(@
(0020|000d) Study Instance UID = 2.16.840.1.113669.632.10.20100308.164732281.0.11
(0020|000e) Series Instance UID = 2.16.840.1.113669.632.10.20100303.160809437.221850
(0020|0010) Study ID =
(0020|0011) Series Number = 22185
(0020|0012) Acquisition Number = 5
(0020|0013) Instance Number = 22185
(0020|0052) Frame of Reference UID = 2.16.840.1.113669.632.10.20100303.160809437.260454.8
(0020|1040) Position Reference Indicator =
(0028|0002) Samples per Pixel = 1
(0028|0004) Photometric Interpretation = MONOCHROME2
(0028|0008) Number of Frames = 250
(0028|0010) Rows = 250
(0028|0011) Columns = 250
(0028|0100) Bits Allocated = 16
(0028|0101) Bits Stored = 12
(0028|0102) High Bit = 11
(0028|0103) Pixel Representation = 0
(0028|0106) Smallest Image Pixel Value = 0
(0028|0107) Largest Image Pixel Value = 4095
(0028|0301) Burned In Annotation = NO
(0028|1050) Window Center = 744.0
(0028|1051) Window Width = 2500.0
(0028|1052) Rescale Intercept = -1000
(0028|1053) Rescale Slope = 1
(0028|2110) Lossy Image Compression = 00
(2050|0020) Presentation LUT Shape = IDENTITY
Patient's Name (0010|0010)  is: Dixson^Dave (m-43y) 88/12/12^^Dr.^
Performing Physician's Name (0008|1050): (No Value Found in File)
PixelType: scalar
Component Type: short



Thanks,
Kourosh