原著
赤外線凝固装置 (KIRC) の基礎的研究
〜シミュレーション解析を用いた心筋組織内熱的変化の評価〜
キーワード:
Kyorin infrared coagulator (KIRC),
two probe tip shapes,
irradiance distribution,
thermal analysis
2021 年 23 巻 1 号 p. 5-14
詳細
2021 年 23 巻 1 号 p. 5-14
The Kyorin infrared coagulator (KIRC) using an infrared halogen lamp is being developed for the surgical treatment of arrhythmia, infective endocarditis, and other disorders; however, no assessments have been conducted on the effects of the shape of its probe tip on irradiance distribution of the irradiation light on the tissue contact surface, or on thermal changes in the myocardial tissue. Therefore, in the present study we performed simulation (analysis of irradiance distribution on tissue contact surface and thermal analysis of myocardial tissue) with differing KIRC probe tip shapes, and assessed the thermal changes in tissue under the infrared irradiation.
In the simulation (using OpticStudio software) of irradiance of the tissue contact surface, we modelled two probe shapes (flat and tapered) and materials, and analyzed the irradiance distribution of the irradiation light (probe tip output 22W) on the tissue contact surface in a two-dimensional coordinate system (X, Y). The specific heat and other environment conditions in the thermal analysis simulation of myocardial tissue with a thermal analysis program (QuickTherm) were set and the tissue model was constructed. With the probe tip output as in OpticStudio, the thermal analysis was performed for the tissue surface (0mm) and depths of 2, 4, and 6mm.
The analysis using OpticStudio showed maximum irradiance values of 40W/cm2 (X, Y=±1, ±1) with the flat tip and 50W/cm2 (X=±1) and 48W/cm2 (Y=±1) with the tapered tip. These findings were applied to the analysis of the tissue model with QuickTherm, which showed temperatures of 64℃ at the surface and 4℃ at 6mm depth with the flat tip and thus higher than those found with the tapered tip. This is presumably attributable to an area of the heat source on the tissue surface with the flat tip that was 2.63 times that with the tapered tip, and accordingly higher heat conduction to a deep region.
In this study, simulation was performed to analyze the irradiance distribution of irradiation light on the tissue contact surfaces with differing probe tip shapes, to elucidate its relation to the thermal effect in the myocardial tissue, and to assess the thermal change in the tissue. In the future, it will be necessary to analyze the relation between the myocardial optical absorption property (wavelength spectrum) and the heat source.
