Could you tell me What is impotant attribute needed for making ruler
for dicom viewer.
I read related topic on group.but it's confuse me that which
attribute(pixel spacing,Imager Pixel Spacing,Nominal Scanned Pixel
Spacing..like that) is important for measurment.
I also saw that some modality haven't these attribute.In that case what
i do?

What is algorithm for calculating physical distance between two point
on image.

With regards