Planar Imaging Module lc_ref_rois


I’m using the Standard Imaging QC-3 phantom and analysis.

I’m trying to access the contrast of the low contrast reference ROI.

The code I’m using is:

qc3 = StandardImagingQC3(BIN_FILE.path)

MVQ_analysis= {
‘ROI 1’ : qc3.lc_rois[0].contrast,
‘ROI 2’ : qc3.lc_rois[1].contrast,
‘ROI 3’ : qc3.lc_rois[2].contrast,
‘ROI 4’ : qc3.lc_rois[3].contrast,
‘ROI 5’ : qc3.lc_rois[4].contrast,
‘Ref ROI’ : qc3.lc_ref_rois.contrast

The lc_rois all seem to work properly but the lc_ref_rois doesn’t work properly. Do you know what I’m doing wrong?

The error I get (in QATrack+) is TypeError: unsupported operand type(s) for -: ‘float’ and ‘NoneType’

Thanks in advance

The problem is that the lc_ref_rois does not have a value set for its background attribute (it’s set to None). I’m not sure if that’s by design (maybe because looking at contrast of the background ROI isn’t meaningful?) or an oversight in the code. If you want the lc_ref_rois contrast you need to set the background attribute like:

qc3.lc_ref_rois.background =

and then accessing the contrast attribute will work ok.


Thanks Randy. Was actually misunderstanding what was meant by the ‘background’.