How to calculate scan length with header dicom for CT?

Hello Dear Colleagues!

We are trying to determine CTDIvol and DLP from CT scans using CT Expo v 2.7.
However, we need to enter the scan length (in cm) into CT Expo. Does anyone know how to calculate the scan length using the information in the DICOM header?
The equipment is old, we only have the following tags:

Single Collimation Width (0018,9306)
SliceLocation (0020,1041)
SliceThickness (0018,0050)

And in addition there is no information in the
SpacingBetweenSlices (0018,0088) tag.

Can anyone help us?
Best regards

Here are a few suggestions, hope they are helpful!

The CTDIvol and DLP is usually stored in a graphical format as the last series in a CT study – an image showing series numbers and CTDI and DLP for the study. Some people do character recognition from that, or just look at it on screen.

The CTDIvol may be in individual images in tag 0018,9345.

DLP relates to a series rather than an image, so isn’t really stored in image headers. Modern scanners can also create a radiation dose structured report, which contain DLP and CTDIvol info, but older ones don’t have such a thing.

You can estimate DLP by taking the minimum and maximum z-axis position from a series of scans, and multiply it by the CTDIvol. This will tend to underestimate the DLP as the irradiation length is actually longer by less than an extra gantry rotation at each end of the scan volume.

@Daiane_Cristini_Barb it would be great if you could let us know if these suggestions solved your problem?

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