diff --git a/VolZmap.h b/VolZmap.h
index c8d6f76..b41d063 100644
--- a/VolZmap.h
+++ b/VolZmap.h
@@ -21,9 +21,8 @@
 #include "/EgtDev/Include/EGkSurfTriMesh.h"
 #include <unordered_map>
 #include <stack>
-#include <mutex>
-#include <atomic>
 #include <tuple>
+#include <atomic>
 
 typedef std::pair<Point3d, Vector3d>  PNTVEC3D ;
 typedef std::vector<PNTVEC3D>        PNTVEC3DVECTOR ;  // vettore di intersezioni punto, vettore, tipo superficie
@@ -557,9 +556,9 @@ class VolZmap : public IVolZmap, public IGeoObjRW
       mutable std::vector<InterVoxMatter> m_SliceXY ;
       mutable std::vector<InterVoxMatter> m_SliceXZ ;
       mutable std::vector<InterVoxMatter> m_SliceYZ ;
-      mutable std::mutex                  m_SliceMutex ;
+      mutable std::atomic_flag            m_SliceFlag ;
 
-      std::atomic<bool>                   m_bIsBox ;
+      bool                                m_bIsBox ;
 
       int                                 m_nCurrTool ;
       std::vector<Tool>                   m_vTool ;
diff --git a/VolZmapGraphics.cpp b/VolZmapGraphics.cpp
index 3159877..2cd8b29 100644
--- a/VolZmapGraphics.cpp
+++ b/VolZmapGraphics.cpp
@@ -1271,13 +1271,15 @@ VolZmap::ExtMarchingCubes( int nBlock, VoxelContainer& vVox) const
                         bDefTopology = true ;
                      }
                      if ( GetBlockNFromIJK( nSlBlockIJK, nSlBlockN)) {
-                        m_SliceMutex.lock() ;
+                        while ( m_SliceFlag.test_and_set( memory_order_acquire))
+                           m_SliceFlag.wait( true, memory_order_relaxed) ;
                         auto it = m_SliceYZ[nSlBlockN].find( nSliceN) ;
                         if ( it != m_SliceYZ[nSlBlockN].end()) {
                            bMatOnSlice = it->second ;
                            bDefTopology = true ;
                         }
-                        m_SliceMutex.unlock() ;
+                        m_SliceFlag.clear( memory_order_release) ;
+                        m_SliceFlag.notify_one() ;
                      }
                   }
                   else if ( abs( nAdjVox3[nCount]) == 2) {
@@ -1287,13 +1289,15 @@ VolZmap::ExtMarchingCubes( int nBlock, VoxelContainer& vVox) const
                         bDefTopology = true ;
                      }
                      if ( GetBlockNFromIJK( nSlBlockIJK, nSlBlockN)) {
-                        m_SliceMutex.lock() ;
+                        while ( m_SliceFlag.test_and_set( memory_order_acquire))
+                           m_SliceFlag.wait( true, memory_order_relaxed) ;
                         auto it = m_SliceXZ[nSlBlockN].find( nSliceN) ;
                         if ( it != m_SliceXZ[nSlBlockN].end()) {
                            bMatOnSlice = it->second ;
                            bDefTopology = true ;
                         }
-                        m_SliceMutex.unlock() ;
+                        m_SliceFlag.clear( memory_order_release) ;
+                        m_SliceFlag.notify_one() ;
                      }
                   }
                   else if ( abs( nAdjVox3[nCount]) == 3) {
@@ -1303,13 +1307,15 @@ VolZmap::ExtMarchingCubes( int nBlock, VoxelContainer& vVox) const
                         bDefTopology = true ;
                      }
                      if ( GetBlockNFromIJK( nSlBlockIJK, nSlBlockN)) {
-                        m_SliceMutex.lock() ;
+                        while ( m_SliceFlag.test_and_set( memory_order_acquire))
+                           m_SliceFlag.wait( true, memory_order_relaxed) ;
                         auto it = m_SliceXY[nSlBlockN].find( nSliceN) ;
                         if ( it != m_SliceXY[nSlBlockN].end()) {
                            bMatOnSlice = it->second ;
                            bDefTopology = true ;
                         }
-                        m_SliceMutex.unlock() ;
+                        m_SliceFlag.clear( memory_order_release) ;
+                        m_SliceFlag.notify_one() ;
                      }
                   }
                }
@@ -1374,27 +1380,33 @@ VolZmap::ExtMarchingCubes( int nBlock, VoxelContainer& vVox) const
                      if ( nSlBlockN == nBlock)
                         SliceYZ.emplace( nSliceN, bMatOnSlice) ;
                      else {
-                        m_SliceMutex.lock() ;
+                        while ( m_SliceFlag.test_and_set( memory_order_acquire))
+                           m_SliceFlag.wait( true, memory_order_relaxed) ;
                         m_SliceYZ[nSlBlockN].emplace( nSliceN, bMatOnSlice) ;
-                        m_SliceMutex.unlock() ;
+                        m_SliceFlag.clear( memory_order_release) ;
+                        m_SliceFlag.notify_one() ;
                      }
                   }
                   else if ( abs(nAdjVox3[nCount]) == 2) {
                      if ( nSlBlockN == nBlock)
                         SliceXZ.emplace( nSliceN, bMatOnSlice) ;
                      else {
-                        m_SliceMutex.lock() ;
+                        while ( m_SliceFlag.test_and_set( memory_order_acquire))
+                           m_SliceFlag.wait( true, memory_order_relaxed) ;
                         m_SliceXZ[nSlBlockN].emplace( nSliceN, bMatOnSlice) ;
-                        m_SliceMutex.unlock() ;
+                        m_SliceFlag.clear( memory_order_release) ;
+                        m_SliceFlag.notify_one() ;
                      }
                   }
                   else if ( abs(nAdjVox3[nCount]) == 3) {
                      if ( nSlBlockN == nBlock)
                         SliceXY.emplace(nSliceN, bMatOnSlice) ;
                      else {
-                        m_SliceMutex.lock() ;
+                        while ( m_SliceFlag.test_and_set( memory_order_acquire))
+                           m_SliceFlag.wait( true, memory_order_relaxed) ;
                         m_SliceXY[nSlBlockN].emplace( nSliceN, bMatOnSlice) ;
-                        m_SliceMutex.unlock() ;
+                        m_SliceFlag.clear( memory_order_release) ;
+                        m_SliceFlag.notify_one() ;
                      }
                   }
                }