We developed a three wavelength time-resolved spectroscopy system cadled the TRS-1 0 for use as a tissue oxygenation monitor. The TRS-1 0 achieved a higher data acquisition rate and a system miniaturization maintaining high sensitivity and time resolution. The TRS-1O consists of a three wavelength picosecond light pulser (PLP) with auto power control as a pulsed light source, a photomultiplier tube (PMT) having high speed and high sensitivity and miniaturized signal processing circuits for time-resolved measurement (CFD, TAC, A/D converter and histogram memory). The TRS-1O system was used to measure the time course of oxygen metabolism in a human forearm with a pneumatic cuff attached to occlude blood flow. Our system succeeded in accurately measuring concentrations of Oxy-(Hb02) and deoxyhemoglobin (Hb) in the human forearm based on diffusion theory by means of TRS data observation having an accumulation time of one second per point.

No abstract

We have developed a 64-channel time-resolved spectroscopy (TRS) system based on a time-correlated single photon counting (TCPC) method to achieve near infrared spectroscopy and/or optical computed tomography (CT) for clinical applications. This system employs advanced devices such as a high power picosecond light pulser (PLP), a high sensitive/fast photomultiplier tube (PMT) and a high speed signal processing circuit. The PLP offers an average optical power of around 0.25 mW, and the PMT has a quantum efficiency greater than 2 % at 800 nm. The signal processing circuit is composed of miniaturized CFD/TAC modules and signal acquisition unit with 1 MHz ADC, and provides 64 independent TCPC circuits for time-of-flight measurement. System perfonnance was estimated by measuring transmitted and reflected light passing through tissue-like phantom models simulating the human breast and infant head. We concluded that this system has the sufficient performance for optical CT utilizing time-of-flight measurement.