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Set background_median and background_std to None when no background ROI's present #355

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Mar 31, 2021
Merged

Set background_median and background_std to None when no background ROI's present #355

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f069364
Set background_median and background_std to None when no background R…
randlet Mar 31, 2021
41b72a7
change background_median to background_mean
randlet Mar 31, 2021
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10 changes: 8 additions & 2 deletions pylinac/ct.py
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Original file line number Diff line number Diff line change
Expand Up @@ -76,6 +76,8 @@ def __init__(self, array: np.ndarray, angle: float, roi_radius: float, dist_from
@property
def cnr(self) -> float:
"""The contrast-to-noise value of the HU disk"""
if self.background_median is None or self.background_std is None:
return None
return 2*abs(self.pixel_value - self.background_median) / (self.std + self.background_std)

@property
Expand Down Expand Up @@ -248,8 +250,12 @@ def _setup_rois(self) -> None:
for name, setting in self.background_roi_settings.items():
self.background_rois[name] = HUDiskROI(self.image, setting['angle_corrected'], setting['radius_pixels'], setting['distance_pixels'],
self.phan_center)
background_median = np.mean([roi.pixel_value for roi in self.background_rois.values()])
background_std = np.std([roi.pixel_value for roi in self.background_rois.values()])
if self.background_rois:
background_median = np.mean([roi.pixel_value for roi in self.background_rois.values()])
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change to mean per your own comment and all good

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Done. Thanks.

background_std = np.std([roi.pixel_value for roi in self.background_rois.values()])
else:
background_median = None
background_std = None

for name, setting in self.roi_settings.items():
nominal_value = setting.get('value', 0)
Expand Down