[Rtk-users] Parker short scan test for enough over scan

[Fredrik Hellman]

Hi,

In rtkParkerShortScanFilter.hxx (line 113) and
rtkCudaParkerShortScanFilter.cxx (line 95), the overscan angle is checked
to be large enough for the used beam fan angle. (There is a difference
between how this check is performed in the two cases. It seems like the
CUDA-version assumes that the piercing point is in the middle of the
detector. That's not what this question is about though.)

The beam fan angle seems to be computed as

arctan( halfDetectorWidth / sourceToIsocenterDistance )

Why sourceToIsocenterDistance? Shouldn't it be sourceToDetectorDistance? If
the detector is far away from the isocenter, the beam fan angle should also
be small as far as I understand. This is not reflected in this computation.

Best regards,
Fredrik Hellman
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