--- a/Core/DicomFormat/DicomInstanceHasher.h	Fri Nov 09 11:13:29 2012 +0100
+++ b/Core/DicomFormat/DicomInstanceHasher.h	Fri Nov 09 11:30:16 2012 +0100
@@ -50,9 +50,14 @@
   {
   private:
     std::string patientId_;
-    std::string instanceUid_;
+    std::string studyUid_;
     std::string seriesUid_;
-    std::string studyUid_;
+    std::string instanceUid_;
+
+    std::string patientHash_;
+    std::string studyHash_;
+    std::string seriesHash_;
+    std::string instanceHash_;
 
   public:
     DicomInstanceHasher(const DicomMap& instance);
@@ -62,9 +67,9 @@
       return patientId_;
     }
 
-    const std::string& GetInstanceUid() const
+    const std::string& GetStudyUid() const
     {
-      return instanceUid_;
+      return studyUid_;
     }
 
     const std::string& GetSeriesUid() const
@@ -72,17 +77,17 @@
       return seriesUid_;
     }
 
-    const std::string& GetStudyUid() const
+    const std::string& GetInstanceUid() const
     {
-      return studyUid_;
+      return instanceUid_;
     }
 
-    std::string HashPatient() const;
+    const std::string& HashPatient();
 
-    std::string HashStudy() const;
+    const std::string& HashStudy();
 
-    std::string HashSeries() const;
+    const std::string& HashSeries();
 
-    std::string HashInstance() const;
+    const std::string& HashInstance();
   };
 }