Shinichi Fujisaka

A Clinical Tissue Oximeter Using NIR Time-Resolved Spectroscopy.

The tNIRS-1, a new clinical tissue oximeter using NIR time-resolved spectroscopy (TRS), has been developed. The tNIRS-1 measures oxygenated, deoxygenated and total hemoglobin and oxygen saturation in living tissues. Two-channel TRS measurements are obtained using pulsed laser diodes (LD) at three wavelengths, multi-pixel photon counters (MPPC) for light detection, and time-to-digital converters (TDC) for time-of-flight photon measurements. Incorporating advanced semiconductor devices helped to make the design of this small-size, low-cost and low-power TRS instrument possible. In order to evaluate the correctness and reproducibility of measurement data obtained with the tNIRS-1, a study using blood phantoms and healthy volunteers was conducted to compare data obtained from a conventional SRS device and data from an earlier TRS system designed for research purposes. The results of the study confirmed the correctness and reproducibility of measurement data obtained with the tNIRS-1. Clinical evaluations conducted in several hospitals demonstrated a high level of usability in clinical situations and confirmed the efficacy of measurement data obtained with the tNIRS-1.

Time-Resolved Imaging Study of Excimer Laser Ablation of Bone

Pig femurs were ablated with a KrF excimer laser (248 nm) at various energy densities. Time—resolved profiles of ablation processes were recorded with a framing camera. The spectral characteristics of the luminescence generated at the irradiated surface were also analyzed. The framing camera experiment showed that the shock waves propagated hemispherically above the surface. The average velocity of the shock waves increased with the laser energy density. A group of the ablation products began to leave the surface after the laser pulse duration. The profile of the ablation products varied with the energy densities. In the spectral analysis, sharp lines were observed. These lines are attributed to the neutral and ionized elements of which bone is composed. This indicates that plasma is produced. 緒言 エキシマレーザーを用いることにより、熱損 傷の少ない骨の切開が可能であることが明らか にされている1)。エキシマレーザーによる骨の 切開機序に関する研究として、噴出物からの発 光強度や誘起電荷量の測定2)、照射部の電子顕 微鏡による観察3)等の報告がある。我々は、レ 、照射部における発光、衝撃波、 噴出物の挙動等の時間的な相互関係を解析する ために、フレー ミングカメラを用いて骨蒸散の 高速コマ撮りを行なった。また、照射部におけ る発光のスペクトル分析を行なった。 -385-