<title>Advanced devices for near-infrared time-resolved spectroscopy and optical computed tomography: high-sensitive/fast PMT, high-power PLP, miniaturized CFD/TAC module, and high-speed multichannel signa</title>

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.

Stationary Headband for Clinical Time‐of‐Flight Optical Imaging at the Bedside

“…A high-power, large detector area device, the UCL multichannel time-resolved system, has recently been described for use in optical tomography and will soon undergo clinical testing (34). In addition, researchers at Hamaniatsu have constructed a 64 channel time-resolved system that has undergone early evaluation with phantom models and may prove suitable for clinical trials (35).…”

Development of a time‐resolved optical tomography system for neonatal brain imaging

“…Time correlated single photon counting (TCSPC) systems [Anders.-Engels 1990, Berg 1993, Benaron 1993b, Oda 1997, Ntziachristos 1999a] also record the whole TPSF, but measure the arrival times of individual photons by comparison with a reference pulse, for instance using a TAC (Time-to-Amplitude Converter) device. TCSPC systems have a very high dynamic range and excellent temporal linearity.…”

“…An advanced 64-channel TCSPC system has been constructed as part of a Japanese MITI funded project that ties together a number of universities and companies. It is a TAC based time-resolved instrument that employs specially developed low power picosecond diode lasers (average power 0.25 mW) and fast PMT detectors [Oda 1997]. The overall system response is reported to be about 150 ps.…”

“…The pulse processing electronics (supplied by EG&G Ortec) has been designed as generalpurpose instrumentation, and could be significantly reduced in both size and cost if the market exists. In fact, similar electronic modules, which are much more compact than the NIM based systems employed in MONSTIR, have been specially developed by Hamamatsu Photonics for optical tomography applications, and are described by [Oda 1997]. Another approach is to incorporate most of the electronics into a PC card, such as the PicoQuant SPC range of time-correlated single photon counting boards.…”