Merge pull request #345 from jrkerns/PYL-339_Add_SSD_parameter_to_pla…

…nar_imaging Closes #339
jrkerns · Mar 11, 2021 · 0232234 · 0232234
2 parents 5de983d + 1c681b5
commit 0232234
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Showing 2 changed files with 11 additions and 4 deletions.
diff --git a/pylinac/planar_imaging.py b/pylinac/planar_imaging.py
@@ -90,6 +90,7 @@ def __init__(self, filepath: str):
         self._center_override = None
         self._high_contrast_threshold = None
         self._low_contrast_threshold = None
+        self._ssd: float = 100
         self.mtf = None
 
     @classmethod
@@ -116,7 +117,7 @@ def _check_inversion(self):
         pass
 
     def analyze(self, low_contrast_threshold: float=0.05, high_contrast_threshold: float=0.5, invert: bool=False, angle_override: Optional[float]=None,
-                center_override: Optional[tuple]=None, size_override: Optional[float]=None) -> None:
+                center_override: Optional[tuple]=None, size_override: Optional[float]=None, ssd: float = 100) -> None:
         """Analyze the phantom using the provided thresholds and settings.
 
         Parameters
@@ -147,12 +148,15 @@ def analyze(self, low_contrast_threshold: float=0.05, high_contrast_threshold: f
             .. Note::
 
                  This value is not necessarily the physical size of the phantom. It is an arbitrary value.
+        ssd
+            The SSD of the phantom itself in cm.
         """
         self._angle_override = angle_override
         self._center_override = center_override
         self._size_override = size_override
         self._high_contrast_threshold = high_contrast_threshold
         self._low_contrast_threshold = low_contrast_threshold
+        self._ssd = ssd
         self._check_inversion()
         if invert:
             self.image.invert()
@@ -587,10 +591,9 @@ def phantom_ski_region(self) -> RegionProperties:
         for phantom_idx, region in enumerate(regions):
             if region.bbox_area < 1000:
                 continue
-            is_at_iso = np.isclose(region.bbox_area, phantom_size_pix, rtol=0.07)
-            is_at_140cm = np.isclose(region.bbox_area, phantom_size_pix/(1.4**2), rtol=0.07)
+            is_at_ssd = np.isclose(region.bbox_area, phantom_size_pix/(self._ssd/100)**2, rtol=0.1)
             centered = np.allclose(region.centroid, img_center, rtol=0.1)
-            if (is_at_iso or is_at_140cm) and centered:
+            if is_at_ssd and centered:
                 blobs.append(phantom_idx)
 
         if not blobs:

diff --git a/tests_basic/test_planar_imaging.py b/tests_basic/test_planar_imaging.py
@@ -111,6 +111,10 @@ class SIQC3_2(PlanarPhantomMixin, TestCase):
     file_path = ['QC3 2.5MV 2.dcm']
     mtf_50 = 0.68
 
+    def test_wrong_ssd_fails(self):
+        with self.assertRaises(ValueError):
+            self.instance.analyze(ssd=140)
+
 
 class LasVegasTestMixin(PlanarPhantomMixin):
     klass = LasVegas