著者

降矢 典雄 大田黒 紘之 酒本 勝之

出版者

Japanese Society for Medical and Biological Engineering

雑誌

生体医工学 (ISSN:1347443X)

巻号頁・発行日

vol.52, pp.O-317-O-318, 2014

---

This study is aimed at investigating possibility of Impedance CT applying two-dimensional analysis. Two-dimensional Electrical Impedance CT has two advantages. This analysis method can estimate internal conductivity distribution faster and the number of required electrodes is fewer compared to three-dimensional analysis. It is suitable for using clinical application. At first, we tried to apply easy filter using the ratio of the potential distribution. However the result of the analysis had the image with noise and indicated not so correct conductivity distribution. The results depend on the relationship between conductivities and positions of the object of different conductivity and tissue around it. It was found that the problem caused by the difference of dimensions occurred. Therefore we need to apply new filter to eliminate the influence of the difference of dimensions. By using a new filter based on Neural Network, it was suggested that the correct conductivity distribution can be obtained.

著者

長岡 智明 櫻井 清子 国枝 悦夫 渡辺 聡一 本間 寛之 鈴木 保 河川 光正 酒本 勝之 小川 幸次 此川 公紀 久保田 勝巳 金 鳳洙 多氣 昌生 山中 幸雄 渡辺 敏

出版者

一般社団法人 日本生体医工学会

雑誌

医用電子と生体工学 (ISSN:00213292)

巻号頁・発行日

vol.40, no.4, pp.239-246, 2002 (Released:2011-10-14)

参考文献数

16

被引用文献数

11

---

We have developed high-resolution voxel models of the whole body from MR images of Japanese adult male and female volunteers. These models can be used for dosimetry simulation of exposure to radiofrequency electromagnetic fields over 1GHz. The MR images were taken by making a series of scans over several days; that is, a subject was scanned in several blocks. Scan parameters were optimized for head and body, respectively, in order to get practical contrast and to save data acquisition time. An implement was used to keep the position and form of the subject. All of the MR images were converted to TIFF format. The continuities between different blocks of the data were corrected to form a whole body. Furthermore, the resolution of the images was changed into 2×2mm. Male and female models were segmented into 51 tissues and organs. This segmentation was performed manually using popular image-processing software. The developed models consisted of isotropic voxels with a side of 2mm. Although the masses of the skin and small-sized tissues and organs of the models deviated from the averaged values for Japanese due to the limitation of spatial resolution, the masses of the other tissues and organs and the morphometric measures were nearly equivalent to those of the average Japanese. The models are the first voxel models of the average Japanese that can be used for the dosimetry of electromagnetic fields over 1GHz. Furthermore, the female model is the first of its kind in the world. The models can also be used for various numerical simulations related to Japanese human bodies in other fields of research.

著者

酒本 勝之

出版者

一般社団法人 日本生体医工学会

雑誌

BME (ISSN:09137556)

巻号頁・発行日

vol.8, no.8, pp.49-56, 1994-08-10 (Released:2011-09-21)

参考文献数

19

被引用文献数

2

著者

藤井 麻美子 戸田 康永 根岸 聡 酒本 勝之 金井 寛

出版者

Japanese Society for Thermal Medicine

雑誌

日本ハイパーサーミア学会誌 (ISSN:09112529)

巻号頁・発行日

vol.13, no.1, pp.18-27, 1997-03-01 (Released:2010-01-28)

参考文献数

3

---

超音波ハイパーサーミアの大きな問題点として, 音響インピーダンスの著しく異なる境界面 (肺や骨など) での発熱があげられる.この発熱は患者に激痛を与え, その結果, 目的部位を十分に加温できなくなる.そして多くの場合, 治療を中断せざるを得なくなる.そこで本研究ではこの問題を筋肉-骨境界面に限定し, その発熱の原因を数値計算とモデル実験により解析した.超音波の伝搬において, 境界面における反射・透過率, さらには伝搬の圧縮波からずり波へのモード変換などは超音波の入射角度に大きく依存するので, 特に温度分布の角度依存性に注目して検討を進めた.

著者

酒本 勝之 金子 和真 江崎 光裕 藤井 麻美子 金井 寛 浅野 次義

出版者

一般社団法人 日本生体医工学会

雑誌

医用電子と生体工学 (ISSN:00213292)

巻号頁・発行日

vol.33, no.3, pp.184-191, 1995 (Released:2011-10-14)

参考文献数

14

被引用文献数

2

---

A new method (BIM) by bioelectrical impedance for the estimation of human whole body or local part fat volume is described. This method is based upon that the resistivity of adipose tissue is much greater than that of fat-free mass of which frequency characteristics shows β dispersion phenomenon. It is well known that the admittance locus of fat-free mass provides the semicircle. Because the impedance value of trunk is only 10 or 20% of the whole body impedance (Zall) between arm and leg used by the commercialized impedance fat meter, if the fat volume in the trunk increase, the estimation error in the fat volume estimated from Zall would increase. Therefore, instead of Zall, BIM adopts the impedances measured at 5 local parts which are antebrachium, brachium, trunk, femoral part and cruralis. We measured the impedance of each parts for the frequency range from 3kHz to 300kHz and calculate the admittance locus in order to obtain the conductance at much lower frequency (Ge) and much higher frequency (Ginf) than β dispersion frequency. Arms, trunk and legs are represented by parallel models which are cone shape and consists of fat layer and fat-free mass layer. And then we calculate the equivalent conductivity σ of parallel models from Ge or Ginf. From σ, fat volumes of local parts which are arm, trunk and leg and whole body are estimated. When we estimate the fat volume of trunk, in order to take into consideration the adipose tissue which distributes around organs in trunk like liver, stomach, and etc., the weighting function K which is statistically given is multiplied to the equivalent conductivity of trunk. The reference fat volume can be measured by hydrometry. We can conclude that (1) the impedance at the trunk must be measured to consider the fat volume in the trunk, (2) Ge or Ginf must be used instead of impedance at about 50kHz to estimate the fat volume, and (3) correlation coefficients between the whole fat volume measured by hydrometry and that by BIM with Ge and Ginf are about 0.77 and 0.94, respectively.

著者

晴山 典彦 藤井 麻美子 酒本 勝之 金井 寛

出版者

一般社団法人 日本生体医工学会

雑誌

医用電子と生体工学 (ISSN:00213292)

巻号頁・発行日

vol.34, no.3, pp.230-237, 1996 (Released:2011-10-14)

参考文献数

6

---

It is very difficult to heat deep seated tumor surrounded by low conductivity tissues, such as bone and fat. We proposed a new RF magnetically induced method for this deep regional hyperthermia. To get high density of induced current in deep tissues, we arranged 4 coils around the sphere agar phantom. The frequency of exciting current is 13.56MHz. In this paper, we will show the calculation method of SAR distribution and temperature distribution in 3D inhomogeneous model. We also discuss the possibility of this heating method from both experiment and calculated results. In the phantom experiment we examined two types of the coils. The calculated results and experimental results show a good agreement, these therefore, the reliability of this calculation method was confirmed. The heating pattern of these coils were not very effective for deep regional hyperthermia. We also calculated temperature distribution in the brain model which was constructed from CT images. We assumed tumor in the brain with half of the blood flow compare to normal tissue. Deep seated tumor was heated by the effect of inhomogeneity and blood flow, except there were hot spots near the coil. In the case of shallow region heating, we can get effective localized heating pattern. From these results, we cannot surely say that this heating method is quite sufficient for deep regional hyperthermia. But since there is no other method to successfully heat the brain non-invasively, this kind of examination with other coil patterns must be continued.

著者

長岡 智明 櫻井 清子 国枝 悦夫 渡辺 聡一 本間 寛之 鈴木 保 河合 光正 酒本 勝之 小川 幸次 此川 公紀 久保田 勝巳 金 鳳洙 多氣 昌生 山中 幸雄 渡辺 敏

出版者

日本エム・イー学会

雑誌

生体医工学 : 日本エム・イー学会誌 = Transactions of the Japanese Society for Medical and Biological Engineering : BME (ISSN:1347443X)

巻号頁・発行日

vol.40, no.4, pp.239-246, 2002-12-10

被引用文献数

42 17

著者

酒本 勝之 田中館 昭博 野城 真理

出版者

北里大学

雑誌

基盤研究(C)

巻号頁・発行日

1996

---

多周波インピーダンスCT装置の製作と多周波インピーダンスCTの応用前に済ましておくべき生体電気特性の基礎的検討を以下の様に行った。1.多周波インピーダンスCT装置の作成:位相検出のため高精度の電子素子を用いた回路設計と試作を行った。その結果、振幅に関し周波数50kHzでの従来のインピーダンスCTで得られた精度と同等の結果が得られた。しかし、高周波数(約100kHz以上)で、浮遊容量の影響、周波数切り替え時での相互干渉が大きく、充分な位相検出の精度が上がらず、設計変更をする必要があった。2.細胞内外液量分布の変化と生体組織の電気インピーダンス変化との関係:細胞内外液量分布の変化と生体組織の電気インピーダンス変化との関係を流動血液を用い、理論と実験を持って検討した。また、有限要素法による数値解(ラプラスの方程式の解)によりシャドウイフェクトの影響を検討した。以上の結果,シャドウイフェクトの影響により、細胞外液抵抗の変化率は細胞外液量の変化率より小さいが、細胞内液抵抗の変化率は細胞内液量の変化率にほぼ等しいことが分かった。3.人工透析時の細胞内外液変動の検討:人工透析時に患者の下肢での電気インピーダンス変化の測定を行ない、人工透析中の細胞内外液の変動を裏付ける結果が得られた。特にショック時でのインピーダンス値は不定期で急激な変動が見られ、細胞内外液量に大きく急激な変動が見られることが示唆された。4.組織温度の変化による組織内血液量の変化の測定:電気インピーダンス法を用い筋組織温の変化による組織内血液量の変化を推定した。温度の上昇により血液量の増加が推測され,従来考えられている通りの結果が得られた。