Terahertz scanning system

The system has a THz source 2 for emitting a THz pulse signal 3 into a region 4. A THz detector 5 receives a reflected THz signal 6 from the region 4, yielding a measurement signal 7. A sensor 9 determines a contact pressure applied to a surface 11 of region 4. A processing system 8 configured to, in response to receiving first and second measurement signals: compare a first measurement signal with a second measurement signal or with a reference measurement signal; determine a degree of deviation between the compared signals; and in dependence thereon, identify a state of the region 4. The first (second) measurement signal may be obtained at a first (second) time at which a first (second) contact pressure has been applied for a first (second) contact duration. The region may be human skin/ tissue and the state may be cosmetic (discolouration, wrinkles) or medical (cancer, disease, dehydration).