Investigation of a high-sensitivity near-infrared-ray computed tomography scanner

In the near-infrared-ray computed tomography (NIR-CT) scanner, NIR rays are produced from a light-emitting diode (LED) and detected using a phototransistor (PT) and an infrared filter. The LED-peak wavelength is 850 nm, and 850- nm-peak NIRs are detected using the filtrated PD. The photocurrents flowing through the PT are converted into voltages using an emitter-follower circuit, and the output voltages are sent to a personal computer through an analog-digital converter. The NIR projection curves for tomography are obtained by repeated translations and rotations of the object, and the translating is conducted in both directions of its movement. The 850-nm NIRs easily penetrated living bodies, and the NIR-CT was performed with changes in the sensitivity at relative sensitivities of 1 and 21.