A technique is suggested (that includes the device's scheme and assessments of its feasibility) for imaging cancer cells in biological tissue samples in vitro and in human skin in vivo, exposing them to 4.2 THz radiation and using a THz-to-infrared (IR) converter in combination with an IR sensitive camera. The converter includes a system of gold nanoparticles embedded into a substance transparent in THz and IR, e.g., Teflon®. The heat exchange between gold nanoparticles and their embedding substance is simulated in a calculation. The convenient size of nanoparticles and their concentration in the substrate are estimated.