### Analog simulation: geometry plot and photon dose rate distribution (logarithmic color scale):

### 1st GVR iteration: importance mesh and photon dose rate distribution (logarithmic color scale):

### 2nd GVR iteration: importance mesh and photon dose rate distribution (logarithmic color scale):

### 3rd GVR iteration: importance mesh and photon dose rate distribution (logarithmic color scale):

### 4th GVR iteration: importance mesh and photon dose rate distribution (logarithmic color scale):