Closes #157

jrkerns · Dec 14, 2018 · ee86c4d · ee86c4d
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diff --git a/docs/source/changelog.rst b/docs/source/changelog.rst
@@ -9,6 +9,14 @@ V 2.2.1
 Bug Fixes
 ^^^^^^^^^
 
+* `#157 <https://github.com/jrkerns/pylinac/issues/157>`_ Dynalog MLC leaf error was calculated incorrectly. Expected positions were off by a row. Error results should be lower on average.
+
+V 2.2.1
+-------
+
+Bug Fixes
+^^^^^^^^^
+
 * `#153 <https://github.com/jrkerns/pylinac/issues/153>`_ Log analyser PDF publishing fix.
 * `#155 <https://github.com/jrkerns/pylinac/issues/155>`_ VMAT PDF report had tolerance listed incorrectly (absolute vs percentage) causing most tolerances to appear as zero.
 

diff --git a/pylinac/log_analyzer.py b/pylinac/log_analyzer.py
@@ -763,7 +763,9 @@ def from_dlog(cls, dlog, jaws, snapshot_data, snapshot_idx):
         """Construct an MLC structure from a Dynalog"""
         mlc = MLC(Dynalog, snapshot_idx, jaws)
         for leaf in range(1, (dlog.header.num_mlc_leaves // 2) + 1):
-            axis = LeafAxis(expected=snapshot_data[(leaf - 1) * 4 + 14], actual=snapshot_data[(leaf - 1) * 4 + 15])
+            # shift expected position per issue #157
+            shifted_expected = cls._shift_expected_mlc_for_dlog(snapshot_data[(leaf - 1) * 4 + 14])
+            axis = LeafAxis(expected=shifted_expected, actual=snapshot_data[(leaf - 1) * 4 + 15])
             mlc.add_leaf_axis(axis, leaf)
 
         # read in "B"-file to get bank B MLC positions. The file must be in the same folder as the "A"-file.
@@ -774,7 +776,9 @@ def from_dlog(cls, dlog, jaws, snapshot_data, snapshot_idx):
 
         # Add bank B MLC positions to mlc snapshot arrays
         for leaf in range(1, (dlog.header.num_mlc_leaves // 2) + 1):
-            axis = LeafAxis(expected=snapshot_data[(leaf - 1) * 4 + 14], actual=snapshot_data[(leaf - 1) * 4 + 15])
+            # shift expected position per issue #157
+            shifted_expected = cls._shift_expected_mlc_for_dlog(snapshot_data[(leaf - 1) * 4 + 14])
+            axis = LeafAxis(expected=shifted_expected, actual=snapshot_data[(leaf - 1) * 4 + 15])
             mlc.add_leaf_axis(axis, leaf + dlog.header.num_mlc_leaves // 2)
 
         # scale dynalog leaf positions from the physical plane to the isocenter plane and from 100ths of mm to cm.
@@ -784,6 +788,14 @@ def from_dlog(cls, dlog, jaws, snapshot_data, snapshot_idx):
             mlc.leaf_axes[leaf].expected *= dynalog_leaf_conversion / 1000
         return mlc
 
+    @staticmethod
+    def _shift_expected_mlc_for_dlog(expected_positions):
+        # insert a copy of the first value
+        extra_position = np.insert(expected_positions, 0, expected_positions[0])
+        # drop the last value so the # of positions are the same
+        shifted_positions = extra_position[:-1]
+        return shifted_positions
+
     @classmethod
     def from_tlog(cls, tlog, subbeams, jaws, snapshot_data, snapshot_idx, column_iter):
         """Construct an MLC instance from a Trajectory log."""

diff --git a/tests_basic/test_logs.py b/tests_basic/test_logs.py
@@ -317,9 +317,9 @@ class TestDynalogDemo(TestIndividualDynalog, TestCase):
     treatment_type = DYNAMIC_IMRT
     num_beamholds = 20
     num_snapshots = 99
-    average_rms = 0.037
-    maximum_rms = 0.076
-    average_gamma = 0.47
+    average_rms = 0
+    maximum_rms = 0
+    average_gamma = 0
     percent_pass_gamma = 91
     leaf_move_status = {'moving': (9, 3), 'static': (8, )}