some question about the lateral distance in the kernal

[Little-Stars520]

In the "ppbkc_generateBaseData.mat" file, the TPR is scaled for different SSD to match the center bixel.

but, at this time, the reference point should no longer be in the isocenter plane(such as SSD:80cm,d:5cm). Why is the lateral distance of the isocenter plane still used in the subsequent kernel convolution?

Could you please explain the explanation of this part in Thomas Bortfeld's article?

[wahln]

Currently I don't really have time to go through this in detail again, but if I remember correctly the reason for this is that the kernel is defined in the fan-line-system (fig 1 in the paper and the transformations below), where the x/y coordinates (x/z in matRad) are equivalent to the coordinates in the isocenter plane.

[wahln]

I will convert this to a discussion, because currently I do not identify it as an issue with matRad