Second value of (0020,0032) Image Position (Patient) does not seem to be used for y origin offset

[Dave-Kiwi]

AMI.js, version V0.32.0

We are importing a set of CT Image DICOM instances, and also an RT Dose DICOM instance. We then overlay STL surfaces created from the associated RT Structure Set object.

When we do this, we notice that the first value of the DICOM attribute Image Position (Patient) (0020,0032) is correctly used for the x coordinate of the viewer (we know this because setting the STL file coordinates using this value and accounting for the coordinate flip gives the correct position in the viewer for the STL surfaces).

However, in the y direction we can only get the structures to line up if we use that same value, and not the second (y) value in (0020,0032) as would normally be used.

I would guess that perhaps the viewer is using the first value of (0020,0032) for both x and y origin, and any test data sets happen to have the same offset from the origin for x and y, and the issue is not being seen. In fact, the issue is not really seen unless the origin offset is not the same in x and y AND DICOM data is mixed with non-DICOM data in the same view.