[Estimation of the phantom scatter factor (Sp) of rectangular fields].

This study proposes a method to accurately estimate the phantom scatter factor (Sp) of arbitrary rectangular fields. We measured output doses in water and air; these measured values were based on square fields and a limited number of symmetric rectangular fields using 4 MV and 10 MV X-rays of a Varian Clinac-iX. We calculated Sp from these measured values. Then, using these Sp values, we estimated equations of Sp on square fields consisting of the primary dose, Day's scatter, and forward scatter. This equation may be used to estimate the Sp value on a square field, but it cannot estimate the Sp value on a rectangular field. We investigated the calculation method for an equivalent square of a rectangular field. As a result, this study's calculation method for an equivalent square, the area ratio correction method, was more accurate than the conventional Bjärngard's method. Therefore, when using the approximate equation of Sp on a square field and the equivalent square calculated by the area ratio correction method, a Sp value of an arbitrary rectangular field may be accurately estimated.

Software-based microwave CT system consisting of antennas and vector network analyzer.

We have developed a software-based microwave CT (SMCT) that consists of antennas and a vector network analyzer. Regardless of the scanner type, SMCT collects the S-parameters at each measurement position in the frequency range of interest. After collecting all the S-parameters, it calculates the shortest path to obtain the projection data for CPMCT. Because of the redundant data in SMCT, the calculation of the projection is easily optimized. Therefore, the system can improve the accuracy and stability of the measurement. Furthermore, the experimental system is constructed at a reasonable cost. Hence, SMCT is useful for imaging experiments for CP-MCT and particularly for basic studies. This paper describes the software-based microwave imaging system, and experimental results show the usefulness of the system.

An attempt of microwave CT system which discriminates the transmission path by means of time domain measurement.

A microwave-based computed tomography system was developed based on a method that uses time domain measurement to determine the shortest path of propagation components between two antennas. The method calculates shortest path of propagation components by examining mixer output DC components, delivering similar precision as chirp-pulse microwave computed tomography. Because post-mixer signal processing need only concerns DC currents, the effects of overshoot characteristics of baseband filters and the like are removed, simplifying measurement. System circuit composition is also simplified, lowering system costs. This paper provides a theoretical framework for the method, an S-parameter verification of the theory, and an experimental verification using a basic hardware construction. Results showed a restored image from the measurement data, indicating the utility of the method for microwave imaging.

Development of non-uniform breast phantom and its microwave imaging for tumor detection by CP-MCT.

Phantom model of the breast which has actual shape and size has been developed for evaluation of microwave imaging by Chirp Pulse Microwave Computed Tomography (CP-MCT). This phantom model will also be successfully used for hyperthermia experiments using microwaves. This phantom model is consisted of four kinds of tissue mimicking materials, that is, the skin-, breast fat-, muscle-, and tumor-simulators. The principal ingredients of the phantom are water, liquid paraffin, super stuff (TX-150), sugar, and salt. It is easy to simulate permittivity of the real breasts in addition to the shape and size. This is the advantage of this non-homogeneous phantom. CP-MCT is a modality for microwave imaging of a human body using chirp pulse microwaves to extract the component which transmits the straight path between two antennas. Possibility of tumor detection by CP-MCT has been demonstrated by using the higher frequency model of CP-MCT and the non-homogeneous breast phantom.

Imaging of forearm-muscle activities by CP-MCT and TR-DOT.

Chirp Pulse Microwave Computed Tomography (CP-MCT) has been developed to visualize activities of forearm muscles during exercise. The change in the gray levels between two images obtained before and after loading exercises showed position dependence. This was produced by physiological- or biochemical- changes in forearm muscles caused by grasping a rubber ball in the bolus tank that was filled with saline solution. However, nobody knows the truth how this change was produced. In order to infer the mechanism of the gray level change caused by the exercise, the forearm exercise was investigated also by using electromyography and Time-Resolved Diffuse Optical Tomography (TR-DOT). Measurements by CP-MCT and TR-DOT were not performed simultaneously, but both images obtained under the same experimental condition showed similar changes in each tomogram. They were characterized by activation of inner muscles needed for continuing the exercise.

In vivo assessment of pigmentary and vascular compartments changes in UVA exposed skin by reflectance-mode confocal microscopy.

Exposure of the skin to ultraviolet A (UVA) results in various biological responses, skin-colour changes being among the major ones. Although intense research has been performed on UVA-induced pigmentation and vascular changes, the process of skin-colour changes after UVA irradiation remains unclear. For a better understanding of the UVA tanning mechanism, we here performed a human study in 27 healthy volunteers with skin phototype (SPT) II to VI. After a single UVA exposure to inner forearm, the skin sites were imaged using reflectance-mode confocal microscopy (RCM), for analysis of melanin and vascular changes. Punch biopsies were also taken from the UVA-exposed or non-exposed sites for histological examination. Skin sections were stained with Fontana-Masson and evaluated by a sensitive tyrosinase assay for comparison with RCM images. Furthermore, the effect of blood flow on skin-colour changes was evaluated visually after administration of an intradermal anesthesia of lidocaine with or without epinephrine. Our RCM analysis showed dendritic melanocytes and a different melanin distribution in the epidermal layer, clearly visible 1 week after the UVA exposure in subjects of SPT V which were supported by histological examination. However, no melanin distribution pattern changes were apparent immediately after the exposure, while RCM images showed accelerated capillary flow patterns. The restriction of this UVA induced-accelerated blood flow by epinephrine inhibited partially or completely the immediate pigment darkening and delayed tanning. These in vivo studies confirmed that vascular change is an important factor for the development of the immediate pigment darkening and delayed tanning.

Development of EOG-based communication system controlled by eight-directional eye movements.

A communication support interface controlled by eye movements and voluntary eye blink has been developed for disabled individuals with motor paralysis who cannot speak. Horizontal and vertical electro-oculograms were measured using two electrodes attached above and beside the dominant eye and referring to an earlobe electrode and amplified with AC-coupling in order to reduce the unnecessary drift. Eight directional cursor movements and one selected operation were realized by logically combining the two detected channel signals based on threshold setting specific to the individuals. As experimental results using a projected screen keyboard, processing speed was improved to 12.1 letters/min. while the accuracy was 90.4%

Evaluation of the preset travel routes in a self-determination support system.

The ability to travel is important for disabled persons. It enables participation in social activities. Although there is a wide range of technologies for assisting the visually impaired to travel, they are under utilized. Part of the explanation lies in the behavioral patterns of many visually impaired who venture outdoors very little. To enable and encourage travel we have developed system to select a travel route that is suitable for a visually impaired traveler. The algorithm uses an analytic hierarchy process (AHP): one among the decision making mathematical models, used with a geographic information system (GIS). The preferred or favored demands of the traveler are reflected quantitatively on the travel route selection. Therefore, it is important to prepare the appropriate travel routes before making use of the system. In this paper we evaluated the preset travel route presumed automatically by the system, using 10 sighted participants as preliminary experiments. As a result, it was verified that several travel routes prepared by our system were available for 60% users.

A smart video magnifier controlled by the visibility signal of a low vision user.

A smart video magnifier for the people with visual disabilities is now being developed to assist their stress-free reading. In a video magnifier, the users watch the monitor screen that is displaying the book page to be read. Eye movement is needed for reading a book. The difficulty of character recognition that is dependent on the environmental conditions is reflected to the eye movement. Accordingly, information on the visibility of the user is extracted as physiological signals accompanied by the gazing motion. These signals are basically used to control the video magnifier. The advantages and usefulness of the adaptive-type video magnifier are discussed in this paper.

The evaluation of skin friction using a frictional feel analyzer.

BACKGROUND/AIMS: Sensory evaluation is an important factor for cosmetic products. Several devices for the measurement of sensory properties have been developed in recent years. The objective here is to measure skin surface friction using these devices and examine the correlation with other physiological parameters in order to evaluate the potential of physical measurement of tactile sensation. METHODS: A KES-SE Frictional Analyzer, a commercial device for measurement of surface frictional characteristics, was used in this study. An arm holder was added to this device for measurement on the human forearm. The frictional coefficient (MIU) and its mean deviation (MMD) were used as the parameter to indicate surface friction. The moisture content in the stratum corneum was measured with a Corneometer CM825, the transepidermal water loss with a Tewameter TM210, the viscoelastic properties of the skin with a Cutometer SEM575 and the skin surface pattern by observing the negative replica using silicon rubber. RESULTS: The MIU was not influenced by load; however, it was increased due to water application on the skin. The relationship between MIU and the moisture content in the stratum comeum, between MMD and skin surface pattern and between MMD and viscosity of both normal human forearm skin and SDS (sodium dodecyl sulfate)-induced dry skin were confirmed by statistical analysis in a test on human subjects. There was also a correlation between either MIU or MMD and sensory evaluation in the morning after the application of moisturizing products. CONCLUSION: Human skin surface friction was measured by using a KES-SE Frictional Analyzer. Judging from the correlation between either MIU or MMD and sensory evaluation, we considered this instrumental analysis to be useful for evaluating the tactile impression of human skin.