I wonder if you have made a change in the orientation between version 1 and 2? When I reconstruct the same data and for SPECT with v2, I get the image upside down compared to version 1. If so – do I need to make anything regarding the orientation of the attenuation map or is it only the output that is flipped?

Left version 2 and right version 1

Hälsningar / Best Regards


Hi Michael,

I am investigating it. There were a few changes in the SPECT system do deal with negative angles with the first-and-last angles option.

Are you specifying all angles for each projection, or do you provide the first and last angles ?
In the latter case, could you give me the values of these angles and say if you specify a detector rotation direction ?

Aside from this, did you try to flip one of the images and do a subtraction to see if the attenuation is indeed correctly taken into account ?

At least, I can say that this is not just the output that is flipped... But you can use option -flip-out to do so if you need to in any circomstances.

Thanks for your active contribution !