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Background We investigated light attenuation at 664 nm, which is the excitation wavelength of photodynamic therapy (PDT) using talaporfin sodium, in a salted cadaver brain. Estimation of therapeutic lesions is important to ensure the effectiveness and safety of brain tumor PDT. Previously reported optical properties of the human brain vary widely. In this study, we measured the light attenuation in brain tissue using a practical method. We employed a salted cadaver brain, in which the mechanical and optical properties can be maintained as close as possible to those under operative conditions. Methods A neuroendoscope was inserted into the brain until the cerebral ventricle was reached. A thin cylindrical diffuser probe was advanced 10 mm from the endoscope tip. By another path from the brain surface, an optical fiber for measurement was inserted into a puncture needle, and a pair of needles was used to puncture the tissue and reach the same cerebral ventricle in which the endoscope tip was positioned. The attenuation of light intensities in the frontal lobe and cerebellum was measured by varying the bundle tip position. The starting positions of the bundle were confirmed by the endoscopic view. The measured light intensity attenuations were fitted with an exponential curve. Results The following attenuation coefficients were obtained: 0.20 ± 0.05 mm−1 in the cerebrum and 0.27 ± 0.05 mm−1 in the cerebellum. Conclusion As conventional spectroscopic measurement may overestimate attenuation in the whole tissue, in situ measurement using the withdrawal technique might be appropriate for measurement of inhomogeneous biological tissues.

A small optical digital transceiver is needed for signal connection among computers, digital terminals, and digital switching frames. Use of optical technology in signal connections between digital frames is supposed to reduce the volume and weight of conventional multicored metal cables and isolate potential interactions between frames. This paper describes recent developments in multichannel optical transceiver technology In which two models of the system are considered and fabricated as the first step in the study.The number of simultaneous transmitting channels needed are 12 for computer buses and 9 for communication buses, and are considered in this paper.