diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 984dd89bc..0782f1ad2 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -278,7 +278,9 @@ jobs:
                         t27_Hits_2SD,
                         t28_Singles_2SD,
                         t29_optical_digi,
-                        t30_dna]
+                        t30_dna,
+                        t32_isotopes,
+                        t33_invert_filter]
 
     steps:
     - name: Checkout github repo
diff --git a/docs/tools_to_interact_with_the_simulation_actors.rst b/docs/tools_to_interact_with_the_simulation_actors.rst
index a5523f499..c052eea73 100644
--- a/docs/tools_to_interact_with_the_simulation_actors.rst
+++ b/docs/tools_to_interact_with_the_simulation_actors.rst
@@ -933,6 +933,10 @@ Filters
 
 Filters are used to add selectrion criteria on actors. They are also used with reduction variance techniques. They are filters on particle type, particle ID, energy, direction....
 
+All filters listed below can be inverted and generate exact opposite selection::
+
+   /gate/actor/[Actor Name]/[Filter Name]/invert
+
 Filter on particle type
 ~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/source/general/include/GateAngleFilterMessenger.hh b/source/general/include/GateAngleFilterMessenger.hh
index f7b9533ef..256ac0983 100644
--- a/source/general/include/GateAngleFilterMessenger.hh
+++ b/source/general/include/GateAngleFilterMessenger.hh
@@ -23,6 +23,7 @@ See LICENSE.md for further details
 
 #include "G4UIcmdWithADoubleAndUnit.hh"
 #include "G4UIcmdWith3Vector.hh"
+#include "G4UIcmdWithoutParameter.hh"
 
 
 class GateAngleFilter;
@@ -41,6 +42,7 @@ protected:
 
   G4UIcmdWithADoubleAndUnit * pSetAngleCmd;
   G4UIcmdWith3Vector        * pSetDirectionCmd;
+  G4UIcmdWithoutParameter* pInvertCmd;
 };
 
 #endif /* end #define GATEANGLEFILTERMESSENGER_HH */
diff --git a/source/general/include/GateCreatorProcessFilterMessenger.hh b/source/general/include/GateCreatorProcessFilterMessenger.hh
index 5bba40fac..53ec8904a 100644
--- a/source/general/include/GateCreatorProcessFilterMessenger.hh
+++ b/source/general/include/GateCreatorProcessFilterMessenger.hh
@@ -19,6 +19,7 @@
 #include "G4UImessenger.hh"
 
 #include "G4UIcmdWithAString.hh"
+#include "G4UIcmdWithoutParameter.hh"
 
 class GateCreatorProcessFilter;
 
@@ -36,6 +37,7 @@ class GateCreatorProcessFilterMessenger :
     GateCreatorProcessFilter *pFilter;
 
     G4UIcmdWithAString* pAddCreatorProcessCmd;
+    G4UIcmdWithoutParameter* pInvertCmd;
 };
 
 #endif
diff --git a/source/general/include/GateEnergyFilterMessenger.hh b/source/general/include/GateEnergyFilterMessenger.hh
index 7d2128f90..f5f60f657 100644
--- a/source/general/include/GateEnergyFilterMessenger.hh
+++ b/source/general/include/GateEnergyFilterMessenger.hh
@@ -21,6 +21,7 @@ See LICENSE.md for further details
 #include "G4UImessenger.hh"
 
 #include "G4UIcmdWithADoubleAndUnit.hh"
+#include "G4UIcmdWithoutParameter.hh"
 
 
 class GateEnergyFilter;
@@ -39,6 +40,7 @@ protected:
 
   G4UIcmdWithADoubleAndUnit * pSetEminCmd;
   G4UIcmdWithADoubleAndUnit * pSetEmaxCmd;
+  G4UIcmdWithoutParameter* pInvertCmd;
 };
 
 #endif /* end #define GATEENEFILTERMESSENGER_HH */
diff --git a/source/general/include/GateIDFilterMessenger.hh b/source/general/include/GateIDFilterMessenger.hh
index 3672a65d7..8d3c410b2 100644
--- a/source/general/include/GateIDFilterMessenger.hh
+++ b/source/general/include/GateIDFilterMessenger.hh
@@ -21,6 +21,7 @@ See LICENSE.md for further details
 #include "G4UImessenger.hh"
 
 #include "G4UIcmdWithAnInteger.hh"
+#include "G4UIcmdWithoutParameter.hh"
 
 
 class GateIDFilter;
@@ -39,6 +40,7 @@ protected:
 
   G4UIcmdWithAnInteger* pAddIDCmd;
   G4UIcmdWithAnInteger* pAddParentIDCmd;
+  G4UIcmdWithoutParameter* pInvertCmd;
 };
 
 #endif /* end #define GATEIDFILTERMESSENGER_HH */
diff --git a/source/general/include/GateMaterialFilterMessenger.hh b/source/general/include/GateMaterialFilterMessenger.hh
index 51634f2df..0aede3375 100644
--- a/source/general/include/GateMaterialFilterMessenger.hh
+++ b/source/general/include/GateMaterialFilterMessenger.hh
@@ -16,6 +16,7 @@ See LICENSE.md for further details
 #include "globals.hh"
 #include "G4UImessenger.hh"
 #include "G4UIcmdWithAString.hh"
+#include "G4UIcmdWithoutParameter.hh"
 
 
 class GateMaterialFilter;
@@ -33,6 +34,7 @@ protected:
   GateMaterialFilter * pMaterialFilter;
 
   G4UIcmdWithAString* pAddMaterialCmd;
+  G4UIcmdWithoutParameter* pInvertCmd;
 };
 
 #endif /* end #define GATEMATFILTERMESSENGER_HH */
diff --git a/source/general/include/GateParticleFilterMessenger.hh b/source/general/include/GateParticleFilterMessenger.hh
index 50fef6dc5..fbbbc8e73 100644
--- a/source/general/include/GateParticleFilterMessenger.hh
+++ b/source/general/include/GateParticleFilterMessenger.hh
@@ -22,6 +22,7 @@ See LICENSE.md for further details
 #include "G4UIcmdWithAString.hh"
 
 #include "G4UIcmdWithAnInteger.hh"
+#include "G4UIcmdWithoutParameter.hh"
 
 class GateParticleFilter;
 
@@ -43,6 +44,7 @@ protected:
   G4UIcmdWithAnInteger* pAddParticlePDGCmd;
   G4UIcmdWithAString* pAddParentParticleCmd;
   G4UIcmdWithAString* pAddDirectParentParticleCmd;
+  G4UIcmdWithoutParameter* pInvertCmd;
 };
 
 #endif /* end #define GATEPARTFILTERMESSENGER_HH */
diff --git a/source/general/include/GateVFilter.hh b/source/general/include/GateVFilter.hh
index f94d6da0f..f9321f284 100644
--- a/source/general/include/GateVFilter.hh
+++ b/source/general/include/GateVFilter.hh
@@ -27,6 +27,8 @@ See LICENSE.md for further details
 #include "G4Step.hh"
 #include "G4Track.hh"
 
+#define _FILTER_RETURN_WITH_INVERSION return IsInverted !=
+
 class GateVFilter : 
   public GateNamedObject
 {
@@ -40,10 +42,14 @@ public:
  
   virtual void show();
 
+  void setInvert(){IsInverted = true;}
  
 
 private:
 
+protected:
+  bool IsInverted = false;
+
 };
 
 
diff --git a/source/general/include/GateVolumeFilterMessenger.hh b/source/general/include/GateVolumeFilterMessenger.hh
index 515d7f664..d689605ff 100644
--- a/source/general/include/GateVolumeFilterMessenger.hh
+++ b/source/general/include/GateVolumeFilterMessenger.hh
@@ -21,6 +21,7 @@ See LICENSE.md for further details
 #include "G4UImessenger.hh"
 
 #include "G4UIcmdWithAString.hh"
+#include "G4UIcmdWithoutParameter.hh"
 
 
 class GateVolumeFilter;
@@ -38,6 +39,7 @@ protected:
   GateVolumeFilter * pVolumeFilter;
 
   G4UIcmdWithAString* pAddVolumeCmd;
+  G4UIcmdWithoutParameter* pInvertCmd;
 };
 
 #endif /* end #define GATEVOLUMEFILTERMESSENGER_HH */
diff --git a/source/general/src/GateAngleFilter.cc b/source/general/src/GateAngleFilter.cc
index 36ff0c7dc..b38360042 100644
--- a/source/general/src/GateAngleFilter.cc
+++ b/source/general/src/GateAngleFilter.cc
@@ -27,9 +27,9 @@ G4bool GateAngleFilter::Accept(const G4Track* aTrack)
   G4ThreeVector stepdirection = aTrack->GetMomentumDirection();
   if(stepdirection.x()*mDirection.x()
      + stepdirection.y()*mDirection.y()
-     + stepdirection.z()*mDirection.z() < std::cos(mAngle) ) return false;
+     + stepdirection.z()*mDirection.z() < std::cos(mAngle) ) _FILTER_RETURN_WITH_INVERSION false;
 
-  return true;
+  _FILTER_RETURN_WITH_INVERSION true;
 }
 //---------------------------------------------------------------------------
 
diff --git a/source/general/src/GateAngleFilterMessenger.cc b/source/general/src/GateAngleFilterMessenger.cc
index b80d38726..fcdbb629f 100644
--- a/source/general/src/GateAngleFilterMessenger.cc
+++ b/source/general/src/GateAngleFilterMessenger.cc
@@ -31,6 +31,7 @@ GateAngleFilterMessenger::~GateAngleFilterMessenger()
 {
   delete pSetDirectionCmd;
   delete pSetAngleCmd;
+  delete pInvertCmd;
 }
 //-----------------------------------------------------------------------------
 
@@ -54,6 +55,11 @@ void GateAngleFilterMessenger::BuildCommands(G4String base)
   pSetDirectionCmd->SetGuidance(guidance);
   pSetDirectionCmd->SetParameterName("direction_x","direction_y", "direction_z", false, false);
 
+  bb = base+"/invert";
+  pInvertCmd = new G4UIcmdWithoutParameter(bb,this);
+  guidance = "Invert the filter";
+  pInvertCmd->SetGuidance(guidance);
+
 }
 //-----------------------------------------------------------------------------
 
@@ -70,6 +76,9 @@ void GateAngleFilterMessenger::SetNewValue(G4UIcommand* command, G4String param)
   {
     pAngleFilter->SetMomentum( pSetDirectionCmd->GetNew3VectorValue(param) );
   }
+  
+  if(command==pInvertCmd) 
+    pAngleFilter->setInvert();
 }
 //-----------------------------------------------------------------------------
 
diff --git a/source/general/src/GateCreatorProcessFilter.cc b/source/general/src/GateCreatorProcessFilter.cc
index ce12d4e95..1c2003c02 100644
--- a/source/general/src/GateCreatorProcessFilter.cc
+++ b/source/general/src/GateCreatorProcessFilter.cc
@@ -31,14 +31,14 @@ GateCreatorProcessFilter::~GateCreatorProcessFilter()
 G4bool GateCreatorProcessFilter::Accept(const G4Track* aTrack) 
 {
   const G4VProcess *creatorProcess = aTrack->GetCreatorProcess();
-  if (!creatorProcess) return false;
+  if (!creatorProcess) _FILTER_RETURN_WITH_INVERSION false;
 
   G4String creatorProcessName = creatorProcess->GetProcessName();
   for (CreatorProcesses::const_iterator iter=creatorProcesses.begin(); iter!=creatorProcesses.end(); iter++)
     if (*iter==creatorProcessName)
-      return true;
+      _FILTER_RETURN_WITH_INVERSION true;
 
-  return false;
+  _FILTER_RETURN_WITH_INVERSION false;
 }
 
 //---------------------------------------------------------------------------
diff --git a/source/general/src/GateCreatorProcessFilterMessenger.cc b/source/general/src/GateCreatorProcessFilterMessenger.cc
index 2f754ab5c..f40d0d46c 100644
--- a/source/general/src/GateCreatorProcessFilterMessenger.cc
+++ b/source/general/src/GateCreatorProcessFilterMessenger.cc
@@ -21,6 +21,11 @@ GateCreatorProcessFilterMessenger::GateCreatorProcessFilterMessenger(GateCreator
     G4String guidance = "Add creator process";
     pAddCreatorProcessCmd->SetGuidance(guidance);
     pAddCreatorProcessCmd->SetParameterName("Creator process name",false);
+
+    bb = base+"/invert";
+    pInvertCmd = new G4UIcmdWithoutParameter(bb,this);
+    guidance = "Invert the filter";
+    pInvertCmd->SetGuidance(guidance);
   }
 }
 //-----------------------------------------------------------------------------
@@ -30,6 +35,7 @@ GateCreatorProcessFilterMessenger::GateCreatorProcessFilterMessenger(GateCreator
 GateCreatorProcessFilterMessenger::~GateCreatorProcessFilterMessenger()
 {
   delete pAddCreatorProcessCmd;
+  delete pInvertCmd;
 }
 //-----------------------------------------------------------------------------
 
@@ -38,6 +44,7 @@ GateCreatorProcessFilterMessenger::~GateCreatorProcessFilterMessenger()
 void GateCreatorProcessFilterMessenger::SetNewValue(G4UIcommand* command, G4String param)
 {
   if(command==pAddCreatorProcessCmd) pFilter->AddCreatorProcess(param);
+  if(command==pInvertCmd) pFilter->setInvert();
 }
 //-----------------------------------------------------------------------------
 
diff --git a/source/general/src/GateEnergyFilter.cc b/source/general/src/GateEnergyFilter.cc
index d9cee3887..312726457 100644
--- a/source/general/src/GateEnergyFilter.cc
+++ b/source/general/src/GateEnergyFilter.cc
@@ -30,10 +30,10 @@ G4bool GateEnergyFilter::Accept(const G4Step* aStep)
     G4double kinetic = aStep->GetPreStepPoint()->GetKineticEnergy();
 
 
-    if ( fLowEnergy!=0. && kinetic < fLowEnergy  ) return false;
-    if ( fHighEnergy!= 0. && kinetic >= fHighEnergy ) return false;
+    if ( fLowEnergy!=0. && kinetic < fLowEnergy  ) _FILTER_RETURN_WITH_INVERSION false;
+    if ( fHighEnergy!= 0. && kinetic >= fHighEnergy ) _FILTER_RETURN_WITH_INVERSION false;
   
-    return true;
+    _FILTER_RETURN_WITH_INVERSION true;
 }
 //---------------------------------------------------------------------------
 
@@ -43,10 +43,10 @@ G4bool GateEnergyFilter::Accept(const G4Track* aTrack)
     G4double kinetic = aTrack->GetKineticEnergy();
 
 
-    if ( fLowEnergy!=0. && kinetic < fLowEnergy  ) return false;
-    if ( fHighEnergy!= 0. && kinetic >= fHighEnergy ) return false;
+    if ( fLowEnergy!=0. && kinetic < fLowEnergy  ) _FILTER_RETURN_WITH_INVERSION false;
+    if ( fHighEnergy!= 0. && kinetic >= fHighEnergy ) _FILTER_RETURN_WITH_INVERSION false;
   
-    return true;
+    _FILTER_RETURN_WITH_INVERSION true;
 }
 //---------------------------------------------------------------------------
 
diff --git a/source/general/src/GateEnergyFilterMessenger.cc b/source/general/src/GateEnergyFilterMessenger.cc
index 5e9472db0..caa050b15 100644
--- a/source/general/src/GateEnergyFilterMessenger.cc
+++ b/source/general/src/GateEnergyFilterMessenger.cc
@@ -31,6 +31,7 @@ GateEnergyFilterMessenger::~GateEnergyFilterMessenger()
 {
   delete pSetEminCmd;
   delete pSetEmaxCmd;
+  delete pInvertCmd;
 }
 //-----------------------------------------------------------------------------
 
@@ -55,6 +56,11 @@ void GateEnergyFilterMessenger::BuildCommands(G4String base)
   pSetEmaxCmd->SetParameterName("Emax", false);
   pSetEmaxCmd->SetDefaultUnit("MeV");
 
+  bb = base+"/invert";
+  pInvertCmd = new G4UIcmdWithoutParameter(bb,this);
+  guidance = "Invert the filter";
+  pInvertCmd->SetGuidance(guidance);
+
 }
 //-----------------------------------------------------------------------------
 
@@ -71,6 +77,8 @@ void GateEnergyFilterMessenger::SetNewValue(G4UIcommand* command, G4String param
     {
       pEnergyFilter->SetEmax(pSetEmaxCmd->GetNewDoubleValue(param) );
     }
+  if(command==pInvertCmd)
+    pEnergyFilter->setInvert();
 }
 //-----------------------------------------------------------------------------
 
diff --git a/source/general/src/GateIDFilter.cc b/source/general/src/GateIDFilter.cc
index f6d0d3f2d..ee05a78f5 100644
--- a/source/general/src/GateIDFilter.cc
+++ b/source/general/src/GateIDFilter.cc
@@ -28,13 +28,13 @@ GateIDFilter::GateIDFilter(G4String name)
 G4bool GateIDFilter::Accept(const G4Track* aTrack) 
 {
 
-  if(mID!=0) if(aTrack->GetTrackID()!=mID) return false;
+  if(mID!=0) if(aTrack->GetTrackID()!=mID) _FILTER_RETURN_WITH_INVERSION false;
 
 
   if(mParentID!=0)
-       if(aTrack->GetParentID()!=mParentID) return false;
+       if(aTrack->GetParentID()!=mParentID) _FILTER_RETURN_WITH_INVERSION false;
 
-  return true;
+  _FILTER_RETURN_WITH_INVERSION true;
 }
 //---------------------------------------------------------------------------
 
diff --git a/source/general/src/GateIDFilterMessenger.cc b/source/general/src/GateIDFilterMessenger.cc
index 1ab575455..08e60862d 100644
--- a/source/general/src/GateIDFilterMessenger.cc
+++ b/source/general/src/GateIDFilterMessenger.cc
@@ -30,6 +30,8 @@ GateIDFilterMessenger::GateIDFilterMessenger(GateIDFilter* idFilter)
 GateIDFilterMessenger::~GateIDFilterMessenger()
 {
   delete pAddIDCmd;
+  delete pAddParentIDCmd;
+  delete pInvertCmd;
 }
 //-----------------------------------------------------------------------------
 
@@ -52,6 +54,11 @@ void GateIDFilterMessenger::BuildCommands(G4String base)
   pAddParentIDCmd->SetGuidance(guidance);
   pAddParentIDCmd->SetParameterName("Parent ID",false);
 
+  bb = base+"/invert";
+  pInvertCmd = new G4UIcmdWithoutParameter(bb,this);
+  guidance = "Invert the filter";
+  pInvertCmd->SetGuidance(guidance);
+
 
 }
 //-----------------------------------------------------------------------------
@@ -64,6 +71,8 @@ void GateIDFilterMessenger::SetNewValue(G4UIcommand* command, G4String param)
     pIDFilter->addID(pAddIDCmd->GetNewIntValue(param));
   if(command==pAddParentIDCmd)
     pIDFilter->addParentID(pAddParentIDCmd->GetNewIntValue(param));
+  if(command==pInvertCmd)
+    pIDFilter->setInvert();
 }
 //-----------------------------------------------------------------------------
 
diff --git a/source/general/src/GateMaterialFilter.cc b/source/general/src/GateMaterialFilter.cc
index c4d4ee1bf..0a9828610 100644
--- a/source/general/src/GateMaterialFilter.cc
+++ b/source/general/src/GateMaterialFilter.cc
@@ -40,10 +40,10 @@ G4bool GateMaterialFilter::Accept(const G4Step* aStep)
     for ( size_t i = 0; i < theMdef.size(); i++){
       if ( theMdef[i] == aStep->GetPreStepPoint()->GetMaterial()->GetName() ) {
         nFilteredParticles++;
-        return true;
+        _FILTER_RETURN_WITH_INVERSION true;
       } 
     }
-  return false;
+  _FILTER_RETURN_WITH_INVERSION false;
 }
 //---------------------------------------------------------------------------
 
@@ -53,10 +53,10 @@ G4bool GateMaterialFilter::Accept(const G4Track* aTrack)
     for ( size_t i = 0; i < theMdef.size(); i++){ 	
       if ( theMdef[i] == aTrack->GetMaterial()->GetName() ) {
         nFilteredParticles++;
-        return true;
+        _FILTER_RETURN_WITH_INVERSION true;
       } 
     }
-  return false;
+  _FILTER_RETURN_WITH_INVERSION false;
 }
 //---------------------------------------------------------------------------
 
diff --git a/source/general/src/GateMaterialFilterMessenger.cc b/source/general/src/GateMaterialFilterMessenger.cc
index feb80c485..308291847 100644
--- a/source/general/src/GateMaterialFilterMessenger.cc
+++ b/source/general/src/GateMaterialFilterMessenger.cc
@@ -32,6 +32,7 @@ GateMaterialFilterMessenger::GateMaterialFilterMessenger(GateMaterialFilter* mat
 GateMaterialFilterMessenger::~GateMaterialFilterMessenger()
 {
   delete pAddMaterialCmd;
+  delete pInvertCmd;
 }
 //-----------------------------------------------------------------------------
 
@@ -47,6 +48,11 @@ void GateMaterialFilterMessenger::BuildCommands(G4String base)
   pAddMaterialCmd->SetGuidance(guidance);
   pAddMaterialCmd->SetParameterName("Material name",false);
 
+  bb = base+"/invert";
+  pInvertCmd = new G4UIcmdWithoutParameter(bb,this);
+  guidance = "Invert the filter";
+  pInvertCmd->SetGuidance(guidance);
+
 }
 //-----------------------------------------------------------------------------
 
@@ -55,6 +61,8 @@ void GateMaterialFilterMessenger::SetNewValue(G4UIcommand* command, G4String par
 {
   if(command==pAddMaterialCmd)
       pMaterialFilter->Add(param);
+  if(command==pInvertCmd)
+      pMaterialFilter->setInvert();
 }
 //-----------------------------------------------------------------------------
 
diff --git a/source/general/src/GateParticleFilter.cc b/source/general/src/GateParticleFilter.cc
index 031dde38c..ccb7eaf51 100644
--- a/source/general/src/GateParticleFilter.cc
+++ b/source/general/src/GateParticleFilter.cc
@@ -47,7 +47,7 @@ G4bool GateParticleFilter::Accept(const G4Track *aTrack)
       }
     }
   } // end thePdef !empty
-  if (!acceptTemp.back()) return false;
+  if (!acceptTemp.back()) _FILTER_RETURN_WITH_INVERSION false;
 
   // Test the particle Z, keep the particle if Z is in the list
   acceptTemp.push_back(true);
@@ -61,7 +61,7 @@ G4bool GateParticleFilter::Accept(const G4Track *aTrack)
       }
     }
   } // end thePdefZ !empty
-  if (!acceptTemp.back()) return false;
+  if (!acceptTemp.back()) _FILTER_RETURN_WITH_INVERSION false;
 
   //// Test the particle A
   acceptTemp.push_back(true);
@@ -75,7 +75,7 @@ G4bool GateParticleFilter::Accept(const G4Track *aTrack)
       }
     }
   } // end thePdefA !empty
-  if (!acceptTemp.back()) return false;
+  if (!acceptTemp.back()) _FILTER_RETURN_WITH_INVERSION false;
 
   // Test the particle PDG
   acceptTemp.push_back(true);
@@ -89,7 +89,7 @@ G4bool GateParticleFilter::Accept(const G4Track *aTrack)
       }
     }
   } // end thePdefPFG !empty
-  if (!acceptTemp.back()) return false;
+  if (!acceptTemp.back()) _FILTER_RETURN_WITH_INVERSION false;
 
   // Test the parent
   acceptTemp.push_back(true);
@@ -110,7 +110,7 @@ G4bool GateParticleFilter::Accept(const G4Track *aTrack)
       trackInfo = GateUserActions::GetUserActions()->GetTrackIDInfo(id);
     }
   } // end theParentPdef !empty
-  if (!acceptTemp.back()) return false;
+  if (!acceptTemp.back()) _FILTER_RETURN_WITH_INVERSION false;
 
   // Test the directParent
   acceptTemp.push_back(true);
@@ -128,10 +128,10 @@ G4bool GateParticleFilter::Accept(const G4Track *aTrack)
       }
     }
   } // end theDirectParentPdef !empty
-  if (!acceptTemp.back()) return false;
+  if (!acceptTemp.back()) _FILTER_RETURN_WITH_INVERSION false;
 
   // Keep the track !
-  return true;
+  _FILTER_RETURN_WITH_INVERSION true;
 }
 //---------------------------------------------------------------------------
 
diff --git a/source/general/src/GateParticleFilterMessenger.cc b/source/general/src/GateParticleFilterMessenger.cc
index 333d5e1af..1072ab0af 100644
--- a/source/general/src/GateParticleFilterMessenger.cc
+++ b/source/general/src/GateParticleFilterMessenger.cc
@@ -30,6 +30,7 @@ GateParticleFilterMessenger::GateParticleFilterMessenger(GateParticleFilter* par
 GateParticleFilterMessenger::~GateParticleFilterMessenger()
 {
   delete pAddParticleCmd;
+  delete pInvertCmd;
 }
 //-----------------------------------------------------------------------------
 
@@ -76,6 +77,11 @@ void GateParticleFilterMessenger::BuildCommands(G4String base)
   guidance = "Add direct parent particle";
   pAddDirectParentParticleCmd->SetGuidance(guidance);
   pAddDirectParentParticleCmd->SetParameterName("Particle name",false);
+
+  bb = base+"/invert";
+  pInvertCmd = new G4UIcmdWithoutParameter(bb,this);
+  guidance = "Invert the filter";
+  pInvertCmd->SetGuidance(guidance);
 }
 //-----------------------------------------------------------------------------
 
@@ -95,6 +101,8 @@ void GateParticleFilterMessenger::SetNewValue(G4UIcommand* command, G4String par
     pParticleFilter->AddParent(param);
   if(command==pAddDirectParentParticleCmd)
     pParticleFilter->AddDirectParent(param);
+  if(command==pInvertCmd)
+    pParticleFilter->setInvert();
 }
 //-----------------------------------------------------------------------------
 
diff --git a/source/general/src/GateVolumeFilter.cc b/source/general/src/GateVolumeFilter.cc
index d42ad8da7..1804e801e 100644
--- a/source/general/src/GateVolumeFilter.cc
+++ b/source/general/src/GateVolumeFilter.cc
@@ -33,9 +33,9 @@ G4bool GateVolumeFilter::Accept(const G4Step* aStep)
    G4LogicalVolume * currentVol = theTouchable->GetVolume(0)->GetLogicalVolume();
 
    for(unsigned int k =0 ; k<theListOfLogicalVolume.size();k++)
-            if(theListOfLogicalVolume[k]== currentVol ) return true;
+            if(theListOfLogicalVolume[k]== currentVol ) _FILTER_RETURN_WITH_INVERSION true;
    
-   return false;
+   _FILTER_RETURN_WITH_INVERSION false;
 }
 //---------------------------------------------------------------------------
 
@@ -49,9 +49,9 @@ G4bool GateVolumeFilter::Accept(const G4Track* t)
    G4LogicalVolume * currentVol = theTouchable->GetVolume(0)->GetLogicalVolume();
 
    for(unsigned int k =0 ; k<theListOfLogicalVolume.size();k++)
-            if(theListOfLogicalVolume[k]== currentVol ) return true;
+            if(theListOfLogicalVolume[k]== currentVol ) _FILTER_RETURN_WITH_INVERSION true;
    
-   return false;
+   _FILTER_RETURN_WITH_INVERSION false;
 }
 
 //---------------------------------------------------------------------------
diff --git a/source/general/src/GateVolumeFilterMessenger.cc b/source/general/src/GateVolumeFilterMessenger.cc
index f3ddcd80f..68f78417e 100644
--- a/source/general/src/GateVolumeFilterMessenger.cc
+++ b/source/general/src/GateVolumeFilterMessenger.cc
@@ -30,6 +30,7 @@ GateVolumeFilterMessenger::GateVolumeFilterMessenger(GateVolumeFilter* idFilter)
 GateVolumeFilterMessenger::~GateVolumeFilterMessenger()
 {
   delete pAddVolumeCmd;
+  delete pInvertCmd;
 }
 //-----------------------------------------------------------------------------
 
@@ -45,6 +46,11 @@ void GateVolumeFilterMessenger::BuildCommands(G4String base)
   guidance = "Add volume";
   pAddVolumeCmd->SetGuidance(guidance);
   pAddVolumeCmd->SetParameterName("Volume name",false);
+
+  bb = base+"/invert";
+  pInvertCmd = new G4UIcmdWithoutParameter(bb,this);
+  guidance = "Invert the filter";
+  pInvertCmd->SetGuidance(guidance);
 }
 //-----------------------------------------------------------------------------
 
@@ -53,6 +59,7 @@ void GateVolumeFilterMessenger::BuildCommands(G4String base)
 void GateVolumeFilterMessenger::SetNewValue(G4UIcommand* command, G4String param)
 {
   if(command==pAddVolumeCmd) pVolumeFilter->addVolume(param);
+  if(command==pInvertCmd) pVolumeFilter->setInvert();
 }
 //-----------------------------------------------------------------------------