Simulation and visualization of scattered radiation

A signalling apparatus comprising:

• a prediction processor for generating a predicted spatial distribution of scattered radiation;
• a radiation sensing device for sensing radiation indicative of a measured spatial distribution of scattered radiation;
• a control unit for providing control signals in response to the predicted and/or the measured spatial distribution of scattered radiation;
• a signalling unit for providing at least one perceptible signal in response to said control signals, said at least one perceptible signal being indicative of the predicted and/or the measured spatial distribution of scattered radiation;
• and
• a position sensing device for sensing a position of an individual and providing a position signal to said control unit in response hereto.