How to find out mm on dicom images

I want a tool like a ruler to measure distances in dicom images. In mm, not in px.

Or at least, how to find out dicom resolution (dpi) so I can easily convert px to mm?

[Payal]

hi..

i am finding the answer for the same query.

that is how to find or measure the resolution of the dicom ct slice(images)?

how can these pixel spacing, number of rows or cols, width helps to find the resolution?

Answer 1

[Rik]

The ReconstructionDiameter field contains the width of your image in mm (at least for CT), PixelSpacing should contain the height and width of your voxels. SliceThickness is the thickness of the slice, but is not the parameter you should use, because the distance between slice centers might not be equal to that (so either an overlap or a gap between slices). I can't find the dicom field name, but you can always calculate it based on the postion fields.

[Stelios Fanourakis]

Where do I find the ReconstructionDiameter?

[Rik]

It should be in the dicom header. What modality is your scan? MRI?

[Stelios Fanourakis]

Ultrasound and cannot fine ReconstructionDiaMETER using Dicominfo

[Rik]

If the header does not contain any personal information, you can attach an example file (you might need to zip it first). Otherwise you can post the contents of the dicominfo struct, removing any identifiable information.

[Payal]

How can these pixel spacing, number of rows or cols, width helps to find the resolution? i am using CT and it does not contain ReconstructionDiameter file, it do contains other info.

[Rik]

What information does your dicom file contain? It should contain sufficient information to derive the size of a pixel.

If I recall correctly, the ReconstructionDiameter is a required field, so it should not be missing in a compliant dicom file.

[Walter Roberson]

pixel spacing is the resolution in the x and y directions, but you need to look at other headers for z resolution.