diff --git a/Device/Detector/SimulationAreaIterator.h b/Device/Detector/SimulationAreaIterator.h
index d938bbc31a69a2f59a5cebf440db101aa7fb611f..d55fa2f1160ccef38f8513f9765a4bb62e3c216e 100644
--- a/Device/Detector/SimulationAreaIterator.h
+++ b/Device/Detector/SimulationAreaIterator.h
@@ -49,7 +49,6 @@ public:
     //! Convenience function to create an end-iterator matching to this iterator.
     SimulationAreaIterator createEnd() const;
 
-    size_t index() const { return m_index; }
     size_t roiIndex() const;
     size_t detectorIndex() const;
 
@@ -65,8 +64,8 @@ public:
 private:
     size_t nextIndex(size_t currentIndex);
 
-    //! Check whether masked according to the given mode (always false if mode is regionOfInterest).
-    //! index is an ROI index.
+    //! Check whether masked according to the actual mode (always false if mode is
+    //! regionOfInterest). index is an ROI index.
     bool isMasked(size_t index) const;
 
     const IDetector* m_detector;
diff --git a/Tests/UnitTests/Core/Instrument/SimulationAreaTest.cpp b/Tests/UnitTests/Core/Instrument/SimulationAreaTest.cpp
index 894ed78547e7270721dcec13cf89e3d1c614292d..6345063281089e35aca5b8587e42707d21a551fe 100644
--- a/Tests/UnitTests/Core/Instrument/SimulationAreaTest.cpp
+++ b/Tests/UnitTests/Core/Instrument/SimulationAreaTest.cpp
@@ -16,13 +16,13 @@ TEST_F(SimulationAreaTest, iteratorOperations)
 
     // begin iterator
     SimulationAreaIterator it_begin = detector.beginNonMaskedPoints();
-    EXPECT_EQ(it_begin.index(), 0u);
+    EXPECT_EQ(it_begin.roiIndex(), 0u);
     EXPECT_TRUE(it_begin == detector.beginNonMaskedPoints());
     EXPECT_FALSE(it_begin != detector.beginNonMaskedPoints());
 
     // end iterator
     SimulationAreaIterator it_end = detector.endNonMaskedPoints();
-    EXPECT_EQ(it_end.index(), detector.totalSize());
+    EXPECT_EQ(it_end.roiIndex(), detector.totalSize());
 
     // begin/end comparison
     EXPECT_TRUE(it_begin != it_end);
@@ -35,16 +35,16 @@ TEST_F(SimulationAreaTest, iteratorOperations)
 
     // increment
     it++;
-    EXPECT_EQ(it.index(), 1u);
+    EXPECT_EQ(it.roiIndex(), 1u);
     EXPECT_TRUE(it != it_begin);
     EXPECT_FALSE(it == it_begin);
     ++it;
-    EXPECT_EQ(it.index(), 2u);
+    EXPECT_EQ(it.roiIndex(), 2u);
 
     // incrementing well behind the end
     for (size_t i = 0; i < 100; ++i)
         ++it;
-    EXPECT_EQ(it.index(), detector.totalSize());
+    EXPECT_EQ(it.roiIndex(), detector.totalSize());
 }
 
 //! Iteration over non-masked detector
@@ -58,7 +58,7 @@ TEST_F(SimulationAreaTest, detectorIteration)
     std::vector<size_t> indexes;
     std::vector<size_t> detectorIndexes;
     for (auto it = detector.beginNonMaskedPoints(); it != detector.endNonMaskedPoints(); ++it) {
-        indexes.push_back(it.index());
+        indexes.push_back(it.roiIndex());
         detectorIndexes.push_back(it.detectorIndex());
     }
     EXPECT_EQ(indexes, expectedIndexes);
@@ -76,7 +76,7 @@ TEST_F(SimulationAreaTest, maskedIteration)
     std::vector<size_t> expectedIndexes = {0, 1, 2, 3, 4, 7, 8, 11, 12, 15, 16, 17, 18};
     std::vector<size_t> indexes;
     for (auto it = detector.beginNonMaskedPoints(); it != detector.endNonMaskedPoints(); ++it)
-        indexes.push_back(it.index());
+        indexes.push_back(it.roiIndex());
     EXPECT_EQ(indexes, expectedIndexes);
 }
 
@@ -93,7 +93,7 @@ TEST_F(SimulationAreaTest, maskedCornerIteration)
     std::vector<size_t> indexes;
     std::vector<size_t> elementIndexes;
     for (auto it = detector.beginNonMaskedPoints(); it != detector.endNonMaskedPoints(); ++it)
-        indexes.push_back(it.index());
+        indexes.push_back(it.roiIndex());
     EXPECT_EQ(indexes, expectedIndexes);
 }
 
@@ -107,7 +107,7 @@ TEST_F(SimulationAreaTest, allMaskedIteration)
     std::vector<size_t> indexes;
 
     for (auto it = detector.beginNonMaskedPoints(); it != detector.endNonMaskedPoints(); ++it)
-        indexes.push_back(it.index());
+        indexes.push_back(it.roiIndex());
 
     EXPECT_EQ(indexes.size(), size_t(0));
 }
@@ -127,7 +127,7 @@ TEST_F(SimulationAreaTest, maskAndRoiIteration)
     std::vector<size_t> detectorIndexes;
     std::vector<size_t> roiIndexes;
     for (auto it = detector.beginNonMaskedPoints(); it != detector.endNonMaskedPoints(); ++it) {
-        indexes.push_back(it.index());
+        indexes.push_back(it.roiIndex());
         detectorIndexes.push_back(it.detectorIndex());
         roiIndexes.push_back(it.roiIndex());
     }
@@ -140,7 +140,7 @@ TEST_F(SimulationAreaTest, maskAndRoiIteration)
     detectorIndexes.clear();
     roiIndexes.clear();
     detector.iterateOverNonMaskedPoints([&](IDetector::const_iterator it) {
-        indexes.push_back(it.index());
+        indexes.push_back(it.roiIndex());
         detectorIndexes.push_back(it.detectorIndex());
         roiIndexes.push_back(it.roiIndex());
     });
@@ -164,7 +164,7 @@ TEST_F(SimulationAreaTest, maskAndRoiIterationVisitMasks)
     std::vector<size_t> roiIndexes;
     for (auto it = detector.beginRegionOfInterestPoints();
          it != detector.endRegionOfInterestPoints(); ++it) {
-        indexes.push_back(it.index());
+        indexes.push_back(it.roiIndex());
         detectorIndexes.push_back(it.detectorIndex());
         roiIndexes.push_back(it.roiIndex());
     }
@@ -177,7 +177,7 @@ TEST_F(SimulationAreaTest, maskAndRoiIterationVisitMasks)
     detectorIndexes.clear();
     roiIndexes.clear();
     detector.iterateOverRegionOfInterest([&](IDetector::const_iterator it) {
-        indexes.push_back(it.index());
+        indexes.push_back(it.roiIndex());
         detectorIndexes.push_back(it.detectorIndex());
         roiIndexes.push_back(it.roiIndex());
     });
@@ -201,7 +201,7 @@ TEST_F(SimulationAreaTest, indexInRoi)
     std::vector<size_t> roiIndexes;
     std::vector<size_t> detectorIndexes;
     for (auto it = detector.beginNonMaskedPoints(); it != detector.endNonMaskedPoints(); ++it) {
-        indexes.push_back(it.index());
+        indexes.push_back(it.roiIndex());
         roiIndexes.push_back(it.roiIndex());
         detectorIndexes.push_back(it.detectorIndex());
     }