Yuta Endo

The Development of Forceps-Type Microwave Tissue Coagulator for Surgical Operation

In this paper, a new type of surgical device for the coagulation and scission of biological tissues, such as blood vessels, using microwave energy is proposed. In addition, the effectiveness of the device for tissue coagulation is evaluated using a numerical analysis and an ex vivo experiment with swine liver tissue. In the numerical analysis, the coagulating capability of the device is evaluated by calculating the temperature distribution inside of the tissue grasped with the device. Microwave energy absorbed by the grasped tissue is used as a heat source for the bioheat transfer equation. In the ex vivo experiment, a prototype of the proposed device is used. The results of these investigations indicate that the proposed device has sufficient coagulating capability of the biological tissue. Moreover, for evaluating the effectiveness of the proposed device in a more realistic condition, an in vivo experiment with the swine tissue has been conducted. In this experiment, venous hemorrhage at the surgical site is stopped using the prototype. As a result, the effectiveness of the proposed device has been confirmed by a surgeon.

Development of forceps type device for biological tissue coagulation by microwave energy

In recent years, various types of medical applications of microwaves have widely been investigated and reported. In this paper, we proposed a novel coagulation device which can be used to heat up by the microwave energy and cut biological tissue by the loaded cutting blade for medical application. In addition, temperature distribution at 2.45 GHz is evaluated by FDTD method.

Evaluation on performances of multiple coaxial-slot antenna for microwave heating compatible with metallic stent for bile duct carcinoma

In this paper, we describe the microwave intracavitary hyperthermia for bile duct carcinoma after the biliary stent placement. We designed a new type of coaxial-slot antenna which has multiple slots near the tip for effective heating along the stent. Therefore, we evaluate the pattern around the stent which is heated by electromagnetic wave leaking from stent efficiently.

Evaluation of electromagnetic interference to implanted cardiac pacemaker due to mobile phone

In recent years, electromagnetic interference (EMI) on implanted cardiac pacemakers due to mobile phones has become a large concern. Here, in the previous studies, dipole antenna or monopole antenna loaded to a metallic case which simulates the PCB, battery etc. were mainly employed as a mobile phone model. However, recent mobile phones are generally equipped with an embedded antenna such as planar inverted-F antenna (PIFA) which have different characteristics from linear antenna. In this study, a realistic mobile phone model consists of 0.1×0.1×0.1 mm3 voxel was employed for calculation of the interference voltage induced at the pacemaker, in order to evaluate the characteristics of the EMI due to mobile phones with existing communication systems. It is consequently shown that the realistic mobile phone model has different characteristics of the interference voltage from those of the simple mobile phone model such as half-wavelength dipole antenna.

Calculations of SAR around implanted cardiac pacemaker induced by wireless radio terminal

Recently, electromagnetic interference (EMI) of an implanted pacemaker induced by a mobile radio terminal has been investigated. However, there are few studies of specific absorption rate (SAR) around the pacemaker induced by the mobile radio terminal. In this paper, the relation between position of pacemaker model embedded into the torso model, wireless radio terminal model and SAR has been investigated. As a result of calculations, possibilities of increasing the SAR were observed in some cases.

Study of Interference Voltage of an Implanted Pacemaker by Mobile Terminals

Electromagnetic interference (EMI) from mobile phones affecting implanted cardiac pacemakers has become a recent concern. In previous numerical computations of the EMI, a half-wavelength dipole antenna has been employed as a radiator of electromagnetic waves. However, current mobile phones are generally equipped with an internal antenna. Furthermore, recent mobile phone systems are operated at higher frequencies, i.e., 2 GHz, whereas lower frequencies around 900 MHz have been assumed in the previous studies. In this study, a mobile phone with an internal antenna was modeled with a planar inverted-F antenna (PIFA) mounted on a metallic case, in order to calculate the interference voltage induced at the pacemaker due to the internal antenna. The PIFA was then scanned in a plane parallel to the torso surface, in order to calculate the interference voltage at each position and to clarify the detailed relationship between the interference voltage and the position of the antenna. Moreover, the interference voltage was experimentally evaluated to validate the numerical calculations. It is shown that the PIFA has interference voltage characteristics, which differ from those of the half-wavelength dipole antenna. Comparing the calculation with the measurement, both results show the same tendency, especially around the position of maximum interference. Therefore, the measured results indicate the validity of the numerical results.

Development of tissue coagulation forceps by microwave energy

In recent years, various types of medical applications using microwave energy have been investigated and reported. In this study, we designed surgical device using microwave energy for hemostasis. This device has a pair of electrode for detecting tissue coagulation. In this paper, we fabricated a prototype of the device and evaluated the effectiveness of hemostasis by heating experiment with swine liver tissue.

Dielectric properties and water contents of biological tissue after microwave heating

In this study, the relationship between the water content ratio [wt%] and the dielectric properties of the dehydrated liver tissues were measured. Employing the results of this study, the numerical dielectric model of dehydrated liver tissue will be developed for the numerical analysis of microwave coagulation therapy (MCT) for liver cancer. Small pieces of swine liver tissue were heated and dehydrated in the household microwave oven to make measurement samples with low water content ratios. The dielectric constants (relative permittivity and conductivity [S/m]) of samples at 2.45 GHz were measured by the open-ended coaxial probe technique. After the measurement of dielectric constants, water content ratios of samples were measured by the loss on drying (LOD) technique. As a result, the relative permittivity and the conductivity of samples strongly depended on water content ratios of them.

Development of microwave tissue coagulator with cutting mechanism

Summary form only given. In recent years, electrical scalpel has widely been used for surgical operation. It employs the radio frequency (RF: from several hundred kHz to several MHz) current and can realize both tissue coagulation and dissection. However, this device has some problems. First, the RF current may through the unexpected part, and it will cause involuntary muscle movement. Moreover, since the device generates excessively high temperature, the biological tissue is carbonized. As a result, fog will be generated. This is one of the serious problems especially in laparoscopic surgery.

Development of forceps-type microwave coagulation device for surgical operation

In recent years, various types of medical applications using heating effect of microwave have widely been investigated and reported. In this study, a novel forceps-shaped device for surgical operations such as blood vessel sealing is proposed. This device has two meander radiation elements to heat up biological tissue between them using microwave energy. In this paper, proposed device was numerically modeled and heating characteristics was evaluated by numerical calculations. As a result, heating capability of the proposed device was confirmed.