Cheng-Yi Wang

Adaptive control of arterial blood pressure with a learning controller based on multilayer neural networks

We discuss a two-model multilayer neural network controller for adaptive control of mean arterial blood pressure (MABP) using sodium nitroprusside. A model with an autoregressive moving average (ARMA), representing the dynamics of the system, and a modified back-propagation training algorithm are used to design the control system to meet specified objectives of design (settling time and undershoot/overshoot) and clinical constraints. The controller is associated with a weighting-determinant unit (WDU) to determine and update the output weighting factor of the parallel two-model neural network for adequate control action and a control-signal modification unit (CMU) to comply with clinical constraints and to suppress the effect of adverse noise and to improve the WDU performance. Extensive computer simulations indicate satisfactory performance and robustness of the proposed controller in the presence of much noise, over the full range of plant parameters, uncertainties, and large variations of parameters.

The effects of ultrasonic stimulation on DP-bioglass bone substitute

In previous studies, DP-bioglass showed good biocompatibility and can form a chemical bond with natural bone. After implementation in the rabbit femur condyle for 32 weeks, DP-bioglass gradually biodegraded and osteocytes grew into the material. In this study, an attempt has been made to utilize low intensity pulsed ultrasound to speed up the bone regeneration rate and DP-bioglass absorption rate when the DP-bioglass is implanted into the rabbit femur condyle as a bone substitute. The fundamental parameters of the ultrasound used were 1.5 MHz frequency, 0.5 W cm-2 intensity, on-off ratio 1:1 and 2 ms for the on-off time interval. The stimulation, in all cases, was started 24 h after the operations by applying the transducer to the skin using DIR ultrasound jelly as a coupling medium. The evaluation of the progress of bone regeneration and the materials biodegradable rate were conducted by histological examination and by measurements of the areas of regenerated bone, pores and DP-bioglass made with a planimeter. It was found that low intensity pulsed ultrasound had a profound effect on the rate both of bone regeneration and DP-bioglass bioabsorption in this rabbit model and that its mechanism of the action may be via an electromechanical kinetic effect on the cell membrane interfaces.

Theoretical study of convergent ultrasound hyperthermia for treating bone tumors

This study investigates the optimal external parameters for using an ultrasound applicator for treating bone tumors. This system utilized spherically arranged applicators such as scanned focused ultrasound, and spherically focused multielement applicators. The power deposition pattern is modeled as geometric gain with exponential attenuation. The specific absorption rate ratio (SARR) criteria have been used to determine the proper heating domain of ultrasound driving frequency and therapeutic tumor diameter. The results demonstrate that the optimal driving frequency depends on tumor depth, ultrasound absorption of bone marrow, and diameter of bone, but it is independent of the acoustic window area and SARR. The treatable diameter of bone tumor increased when the absorption ratio of bone marrow to tumor, acoustic window of surface skin, and diameter of bone were elevated. However, the treatable diameter of bone tumor decreased when muscle thickness, SARR of bone tumor site to the surface skin, bone marrow, and bone declined. To deliver the ultrasound energy into the tumor site and to avoid the potential damage to the normal tissue as much as possible, the specific absorption rate (SAR) in the bone tumor site has to be three times higher than that in the surface skin, tumor/marrow, and marrow/bone interfaces. The temperature distributions can verify the SARR criteria in this model. This study provides the information for choosing the optimal operating frequency of the ultrasound transducer and the acoustic window on the skin surface, and for designing the ultrasound applicator for clinical implementation.

Portable current stimulator for transdermal iontophoretic drug delivery

A pulse stimulator was designed. It is small sized (3 x 2 cm printed circuit board) and battery-powered (185 microA total static current). The current intensity and pulse duration of this device can be continuously varied. Preliminary trials of lidocaine show that this device is usable for transdermal drug delivery and may be valuable for portable applications.

Microcomputer-based pulse stimulator

A low-cost PC-based 2-channel stimulator was designed. This device can generate regular current pulses for many neuroscience experiments. It can also generate irregular pulses for nerve stimulation, thus could possibly avoid the problem of sensitization or habituation in the central nervous system. The stimulation frequency (can be < 0.0005 Hz) and pulse duration (5 microseconds to 65 ms) of this device can be programmed by an interactive user interface. Furthermore, the output current (0-10 mA) can be continuously varied and was optically isolated to minimize stimulus artifact. Moreover, features such as low-power consumption (0.2 mA of a 9 V battery) and high-compliance output (> 120 V) could accommodate the stimulator for widespread applications. A trial of nerve stimulation was illustrated besides the electrical specifications of the stimulator.

Blood pressure regulation by means of a neuro-fuzzy control system

A two-model multilayered neural networks (MNN) controller with modified back-propagation training algorithm is designed to adaptively control the mean arterial blood pressure. The controller is also associated with a fuzzy logic unit (LGU) to determine an incremental value and update the output weighting factor of the parallel two-model MNN controller for adequate control action. Extensive computer simulations indicate satisfactory performance and robustness of the proposed controller in the presence of much noise, over the full range of plant parameters, uncertainties and large variations of parameters.

A multifrequency driving system for ultrasound hyperthermia

Compared with a single-frequency system, the multiple-frequency system has an additional function to combine power patterns of different frequencies. This function increases the availability of power patterns to treat various shapes and depths of tumors. Therefore, we proposed a system with the ability to drive ultrasonic phased arrays of multiple resonant frequencies for ultrasound hyperthermia.

A Information Management Strategy for In-House Clinical Engineering Department Based on Equipment Service Life-Cycle Model

In the hospital, the management of medical equipments is a series of activities from budget planning to equipment disposing. The overall activities focus on issues such as quality, safety, performance, cost, and profit. An efficient and effective management system is necessary for supervising these goals. In this study, we show an equipment service life-cycle model applied in these activities for in-house clinical engineering department. Some information systems were built by the model and the information of management operations in clinical engineering department can be systematic collected and revealed at different life-cycle stages by these systems. Through the model, we can easily integrate the management activities and improve medical care quality and patient’s safety. The model will be introduced in the method section and four systems which are medical equipment management system, utilization benefit administrative system, regulatory management system, and emergency management system will be shown in the results section. The framework of this model has worked well in National Taiwan University Hospital.

TWO-DIMENSIONAL STATIC AND DYNAMIC DISPLAY SYSTEM OF BOWEL SOUND MAGNITUDE MAP FOR EVALUATION OF INTESTINAL MOTILITY

The aim of this work is to develop a new technique of two-dimensional (2D) bowel sound magnitude map (BSMM) with multichannel electronic stethoscopes to evaluate the location, intensity, and track of intestinal motility from the abdominal surface in real time. The static BSMM, obtained from the interpolation of captured one-dimensional (1D) signals, demonstrated an activity level of intestinal motility with different colors. It enabled spatial visualization of the sound origin to locate the peristaltic position of bowels. The dynamic BSMM, displayed in either time series or continuous mode, clearly showed the tracking pattern of intestinal motility on the whole abdomen. Our results verified the validation of this system with a computer simulation and the specific detection of bowel sounds (BSs). The detection of physiologic intestinal motility, including that before and after meal or before defecation, is also available with BSMMs. A simple, noninvasive, low-cost, visualizable, and real-time device has been successfully developed in this work.

The temperature distributions of bone tumor therapy using scanned focused ultrasound system

The temperature distributions of bone tumor therapy using scanned focused ultrasound hyperthermic system (SFUS) have been simulated. The power arrays in SFUS have been tilted, rotated, translated and convoluted to obtain the power distributions. The temperature distributions are calculated by 3-D bio-heat transfer equation (BHTE). The simulation results reveal that the overheating on bone occurs when tilt angle and rotation angle decrease, but when scanning radius toward the tumor increases.