A diffuse-optical-spectroscopy system and method for scanning human tissue is provided. The system includes: (a) a handheld probe operable to emit electromagnetic radiation at one or more wavelengths corresponding to absorption associated with one or more human-tissue constituents, respectively, the handheld probe being operable to detect received electromagnetic radiation at each of the wavelengths; and (b) a processor operable to produce, in response to the received electromagnetic radiation, one or more cross-sectional images of the human tissue respectively associated with the wavelengths. The handheld probe includes first and second sources for emitting the electromagnetic radiation and one or more sensors for detecting the received electromagnetic radiation. The sensors are aligned along a first axis and face in an outward direction. The first and second sources are aligned along the first axis, face in the outward direction, and are disposed on either side of the sensors.