diff --git a/Framework/DataHandling/src/RotateSampleShape.cpp b/Framework/DataHandling/src/RotateSampleShape.cpp
index cc76b73b7194..4d107472cb8b 100644
--- a/Framework/DataHandling/src/RotateSampleShape.cpp
+++ b/Framework/DataHandling/src/RotateSampleShape.cpp
@@ -76,14 +76,14 @@ void RotateSampleShape::exec() {
     g_log.warning() << "Empty goniometer created; will always return an "
                        "identity rotation matrix.\n";
 
-  const auto sampleShapeRotation = gon.getR();
+  const auto &sampleShapeRotation = gon.getR();
   if (sampleShapeRotation == Kernel::Matrix<double>(3, 3, true)) {
     // If the resulting rotationMatrix is Identity, ignore the calculatrion
     g_log.warning("Rotation matrix set via RotateSampleShape is an Identity matrix. Ignored rotating sample shape");
     return;
   }
 
-  const auto oldRotation = ei->run().getGoniometer().getR();
+  const auto &oldRotation = ei->run().getGoniometer().getR();
   auto newSampleShapeRot = sampleShapeRotation * oldRotation;
   if (isMeshShape) {
     auto meshShape = std::dynamic_pointer_cast<MeshObject>(ei->sample().getShapePtr());
diff --git a/docs/source/release/v6.12.0/Framework/Algorithms/Bugfixes/38063.rst b/docs/source/release/v6.12.0/Framework/Algorithms/Bugfixes/38063.rst
new file mode 100644
index 000000000000..6fe28f083b44
--- /dev/null
+++ b/docs/source/release/v6.12.0/Framework/Algorithms/Bugfixes/38063.rst
@@ -0,0 +1 @@
+- Fixed a bug in :ref:`sample_transmission_calculator` (Interfaces > General > Sample Transmission Calculator) interface to restrict entering commas mixed with decimal point in the double spin boxes for Low, Width and High fields
diff --git a/qt/python/mantidqtinterfaces/mantidqtinterfaces/SampleTransmissionCalculator/stc_view.py b/qt/python/mantidqtinterfaces/mantidqtinterfaces/SampleTransmissionCalculator/stc_view.py
index d9ad9f06d136..0faa2cabd240 100644
--- a/qt/python/mantidqtinterfaces/mantidqtinterfaces/SampleTransmissionCalculator/stc_view.py
+++ b/qt/python/mantidqtinterfaces/mantidqtinterfaces/SampleTransmissionCalculator/stc_view.py
@@ -36,6 +36,19 @@ def __init__(self, parent=None):
             "Or 0,100,10000,200,20000: from 0 rebin in steps of 100 to 10,000 then steps of 200 to 20,000."
         )
 
+        self.single_high_spin_box.textChanged.connect(self._double_spinbox_textChanged)
+        self.single_low_spin_box.textChanged.connect(self._double_spinbox_textChanged)
+        self.single_width_spin_box.textChanged.connect(self._double_spinbox_textChanged)
+
+    def _double_spinbox_textChanged(self, text):
+        if "," in text:
+            text = text.replace(",", ".")
+            oldState = self.sender().blockSignals(True)
+            self.isEditing = True
+            self.sender().setValue(float(text))
+            self.sender().lineEdit().setText(f"{self.sender().value():.1f}")
+            self.sender().blockSignals(oldState)
+
     def get_input_dict(self):
         input_dict = {
             "binning_type": self.binning_type_combo_box.currentIndex(),