Use Pixel Spacing for SC only with SecondaryCaptureImagePlaneModule

Default to the GetSpacingTagFromMediaStorage, which is Nominal Scanned Pixel Spacing for Secondary Capture. Only use Pixel Spacing (0028,0030) when the SecondaryCaptureImagePlaneModule flag has been enabled on ImageHelper. Add documentation to Set/GetSecondaryCaptureImagePlaneModule accordingly.
malaterre · Mar 25, 2024 · 0cca908 · 0cca908
1 parent 2abdfcf
commit 0cca908
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Showing 2 changed files with 18 additions and 18 deletions.
diff --git a/Source/MediaStorageAndFileFormat/gdcmImageHelper.cxx b/Source/MediaStorageAndFileFormat/gdcmImageHelper.cxx
@@ -1400,7 +1400,20 @@ std::vector<double> ImageHelper::GetSpacingValue(File const & f)
   MediaStorage ms;
   ms.SetFromFile(f);
   const DataSet& ds = f.GetDataSet();
-  Tag spacingtag(0xffff,0xffff);
+  Tag spacingtag = GetSpacingTagFromMediaStorage(ms);
+  if( ms == MediaStorage::SecondaryCaptureImageStorage && SecondaryCaptureImagePlaneModule )
+    {
+      if( ds.FindDataElement( Tag(0x0028,0x0030) ) )
+        {
+        // Type 1C in 'SC Image' (for calibrated images)
+        spacingtag = Tag(0x0028,0x0030);
+        }
+      else if( ds.FindDataElement( Tag(0x0018,0x2010) ) )
+        {
+        // Type 3 in 'SC Image'
+        spacingtag = Tag(0x0018,0x2010);
+        }
+    }
 
   if( ms == MediaStorage::EnhancedCTImageStorage
     || ms == MediaStorage::EnhancedMRImageStorage
@@ -1463,23 +1476,6 @@ std::vector<double> ImageHelper::GetSpacingValue(File const & f)
       return sp;
       }
     }
-  else if( ms == MediaStorage::SecondaryCaptureImageStorage )
-    {
-      if( ds.FindDataElement( Tag(0x0028,0x0030) ) )
-        {
-        // Type 1C in 'SC Image' (for calibrated images)
-        spacingtag = Tag(0x0028,0x0030);
-        }
-      else if( ds.FindDataElement( Tag(0x0018,0x2010) ) )
-        {
-        // Type 3 in 'SC Image'
-        spacingtag = Tag(0x0018,0x2010);
-        }
-    }
-  else
-    {
-    spacingtag = GetSpacingTagFromMediaStorage(ms);
-    }
 
   if( spacingtag != Tag(0xffff,0xffff) && ds.FindDataElement( spacingtag ) && !ds.GetDataElement( spacingtag ).IsEmpty() )
     {

diff --git a/Source/MediaStorageAndFileFormat/gdcmImageHelper.h b/Source/MediaStorageAndFileFormat/gdcmImageHelper.h
@@ -88,6 +88,10 @@ class GDCM_EXPORT ImageHelper
   /// Opt into Image Plane Module for Secondary Capture Image Storage
   /// Enable reading Image Position Patient (IPP) and Image Orientation Patient (IOP)
   /// for Secondary Capture Image Storage.
+  /// Also, pixel spacing will be based on a Pixel Spacing tag (0028,0x0030), if present, and fall
+  /// back to Nominal Scanned Pixel Spacing (0018,2010), if present, as described:
+  /// https://dicom.nema.org/medical/dicom/current/output/chtml/part03/sect_C.8.6.2.html#table_C.8-2
+  /// https://dicom.nema.org/medical/dicom/current/output/chtml/part03/sect_10.7.html#table_10-10
   static void SetSecondaryCaptureImagePlaneModule(bool);
   static bool GetSecondaryCaptureImagePlaneModule();