Tongning Wu

Chinese adult anatomical models and the application in evaluation of RF exposures

This paper presents the work of constructing Chinese adult anatomical models and their application in evaluation of radio frequency (RF) electromagnetic field exposures. The original dataset was obtained from photos of the sliced frozen cadavers from the Chinese Visible Human Project. Details of preparing the cadaver for slicing procedures which may influence the anatomical structures are discussed. Segmentation and reconstruction were performed mainly manually by experienced anatomists. The reconstructed models represent the average Chinese in their twenties and thirties. The finest resolution for the models is 1 × 1 × 1 mm(3) with 90 identified tissues/organs for the female and 87 identified tissues/organs for the male. Tiny anatomical structures such as blood vessels with diameters of 1 mm, various glands and nerves were identified. Whole-body-averaged specific absorption rate (WBSAR) from 20 MHz to 5.8 GHz was calculated with the finite-difference time-domain method for different RF exposure configurations. The WBSAR results are consistent with those from other available models. Finally, some details about the anatomical models are discussed.

Generation of infant anatomical models for evaluating electromagnetic field exposures

Realistic anatomical modeling is essential in analyzing human exposure to electromagnetic fields. Infants have significant physical and anatomical differences compared with other age groups. However, few realistic infant models are available. In this work, we developed one 12-month-old male whole body model and one 17-month-old male head model from magnetic resonance images. The whole body and head models contained 28 and 30 tissues, respectively, at spatial resolution of 1 mm × 1 mm × 1 mm. Fewer identified tissues in the whole body model were a result of the low original image quality induced by the fast imaging sequence. The anatomical and physical parameters of the models were validated against findings in published literature (e.g., a maximum deviation as 18% in tissue mass was observed compared with the data from International Commission on Radiological Protection). Several typical exposure scenarios were realized for numerical simulation. Dosimetric comparison with various adult and child anatomical models was conducted. Significant differences in the physical and anatomical features between adult and child models demonstrated the importance of creating realistic infant models. Current safety guidelines for infant exposure to radiofrequency electromagnetic fields may not be conservative.

The alteration of spontaneous low frequency oscillations caused by acute electromagnetic fields exposure

OBJECTIVE The motivation of this study is to evaluate the possible alteration of regional resting state brain activity induced by the acute radiofrequency electromagnetic field (RF-EMF) exposure (30min) of Long Term Evolution (LTE) signal. METHODS We designed a controllable near-field LTE RF-EMF exposure environment. Eighteen subjects participated in a double-blind, crossover, randomized and counterbalanced experiment including two sessions (real and sham exposure). The radiation source was close to the right ear. Then the resting state fMRI signals of human brain were collected before and after the exposure in both sessions. We measured the amplitude of low frequency fluctuation (ALFF) and fractional ALFF (fALFF) to characterize the spontaneous brain activity. RESULTS We found the decreased ALFF value around in left superior temporal gyrus, left middle temporal gyrus, right superior temporal gyrus, right medial frontal gyrus and right paracentral lobule after the real exposure. And the decreased fALFF value was also detected in right medial frontal gyrus and right paracentral lobule. CONCLUSIONS The study provided the evidences that 30min LTE RF-EMF exposure modulated the spontaneous low frequency fluctuations in some brain regions. SIGNIFICANCE With resting state fMRI, we found the alteration of spontaneous low frequency fluctuations induced by the acute LTE RF-EMF exposure.

Creation of a female and male segmentation dataset based on Chinese Visible Human (CVH)

OBJECTIVE Segmentation is a necessary step when creating realistic three-dimensional (3D) models. In order to build 3D models of whole body structures and have a wider lateral application, the thin sectional anatomical images of the Chinese Visible Human (CVH) dataset should be segmented. The more detailed structures are segmented to provide greater potential for wider application of the segmented images. MATERIALS AND METHODS All the images based on the CVH male and female dataset were segmented semi-automatically using PHOTOSHOP software. This research lasted about 7 years. RESULT In this study, 869 structures of CVH male and 860 structures of CVH female were semi-automatically segmented, and the formats for the segmented color-filled image data were PSD and PNG. In these segmented structures, nearly all skeletal muscles included muscle belly and tendon, and hollow organs included their organ walls and their lumen. Most nerve trunks, small arteries, lymph nodes, and lymph ducts were also segmented. Many surface-rendering and volume-rendering organ models were created using these segmented images. CONCLUSION The CVH male and female images represent the normal Asian population. After segmentation, the images can be reconstructed directly in 3D and greatly facilitate the biological modeling of physical and physiological information, a great help in improving medical and biological science in China.

Reduced prefrontal activation during a verbal fluency task in Chinese-speaking patients with schizophrenia as measured by near-infrared spectroscopy

Near-infrared spectroscopy (NIRS) has been applied to examine the possible functional alternations during the performance of cognitive tasks in schizophrenia. With this technique, previous studies have observed that patients with schizophrenia are often associated with reduced brain activation in the prefrontal cortex during the verbal fluency task (VFT) of the English version or the Japanese version. However, it remains unclear whether there is a brain functional impairment in Chinese-speaking patients with schizophrenia. In this study, we designed a Chinese version of the VFT and performed a multichannel NIRS study in a large group of patients with schizophrenia and healthy controls. We investigated brain activation during the task period of the Chinese version of the VFT within a schizophrenia group and a healthy group, respectively, and compared the relative changes between the two groups. Our results confirmed that Chinese-speaking patients with schizophrenia had significantly lower brain activation in the prefrontal cortex and superior temporal cortex when compared with healthy controls. Such findings based on the NIRS data provided us reliable evidences about brain functional deficits in the Chinese-speaking patients with schizophrenia.

Evaluation of different classification methods for the diagnosis of schizophrenia based on functional near-infrared spectroscopy.

BACKGROUND Based on near-infrared spectroscopy (NIRS), recent converging evidence has been observed that patients with schizophrenia exhibit abnormal functional activities in the prefrontal cortex during a verbal fluency task (VFT). Therefore, some studies have attempted to employ NIRS measurements to differentiate schizophrenia patients from healthy controls with different classification methods. However, no systematic evaluation was conducted to compare their respective classification performances on the same study population. NEW METHOD In this study, we evaluated the classification performance of four classification methods (including linear discriminant analysis, k-nearest neighbors, Gaussian process classifier, and support vector machines) on an NIRS-aided schizophrenia diagnosis. We recruited a large sample of 120 schizophrenia patients and 120 healthy controls and measured the hemoglobin response in the prefrontal cortex during the VFT using a multichannel NIRS system. Features for classification were extracted from three types of NIRS data in each channel. We subsequently performed a principal component analysis (PCA) for feature selection prior to comparison of the different classification methods. RESULTS We achieved a maximum accuracy of 85.83% and an overall mean accuracy of 83.37% using a PCA-based feature selection on oxygenated hemoglobin signals and support vector machine classifier. COMPARISON WITH EXISTING METHODS This is the first comprehensive evaluation of different classification methods for the diagnosis of schizophrenia based on different types of NIRS signals. CONCLUSIONS Our results suggested that, using the appropriate classification method, NIRS has the potential capacity to be an effective objective biomarker for the diagnosis of schizophrenia.

Slice-based supine-to-standing posture deformation for Chinese anatomical models and the dosimetricresults with wide band frequency electromagnetic field exposure: simulation

Digital human models are frequently obtained from supine-postured medical images or cadaver slices, but many applications require standing models. This paper presents the work of reconstructing standing Chinese adult anatomical models from supine postured slices. Apart from the previous studies, the deformation works on 2-D segmented slices. The surface profile of the standing posture is adjusted by population measurement data. A non-uniform texture amplification approach is applied on the 2-D slices to recover the skin contour and to redistribute the internal tissues. Internal organ shift due to postures is taken into account. The feet are modified by matrix rotation. Then, the supine and standing models are utilised for the evaluation of electromagnetic field exposure over wide band frequency and different incident directions.

Dosimetric study on eye's exposure to wide band radio frequency electromagnetic fields: Variability by the ocular axial length

This paper evaluates the variability of specific absorption rate (SAR) in the human eye. This variability results from changes in ocular axial length (OAL), which is common in many ophthalmologic and vision abnormalities, including myopia. A generic eye model was reconstructed according to published data. The feasibility of using the generic model in numerical research of electromagnetic fields (EMF) was demonstrated by means of comparative simulations with eye models reconstructed from magnetic resonance (MR) scans. Free-form deformation (FFD) was used to deform the OAL of the generic eye model. Thus, 64 deformed eyes were created and were categorized according to the OAL increase. The finite-difference time-domain (FDTD) method was applied in the simulations. The results revealed that changing the OAL does not increase EMF absorption in the eyes or the eye tissues. No additional induced temperature rise was produced by the changes of OAL. The results also indicated that the non-pathological increment of the OAL, which is inevitable during the childhood, does not increase the SAR in the eyes.

Dosimetry of infant exposure to power-frequency magnetic fields: Variation of 99th percentile induced electric field value by posture and skin-to-skin contact

Infant exposure to 50 Hz magnetic fields from power lines was numerically analyzed in this study. Dosimetric variability due to posture and skin-to-skin contact was evaluated using human anatomical models including a recently developed model of a 12-months-old infant. As proposed by the International Commission on Non-Ionizing Radiation Protection, the induced E-field strength (99th percentile value, E99 ) for the central nerve systems (E99_CNS ) and peripheral nerve system (E99_PNS ), were used as metrics. Results showed that the single (free of contact with others) infant model has lower E99 (E99_CNS and E99_PNS inclusive) compared with single adult and child models when exposed to the same power-frequency magnetic field. Also, studied postures of sitting, standing, or arm-up, would not change E99 _PNS . However, skin-to-skin contact with other models could significantly raise induced E-field strength in the infant (e.g., contact on 0.93% of the infants total surface increased E99_PNS by 213%). Simulations with canonical models were conducted to assess different factors contributing to the E99 enhancement. Results indicated the importance of thoroughly investigating the conservativeness of current safety guidelines in the case of skin-to-skin contact, especially with infants.

Long-Term Evolution Electromagnetic Fields Exposure Modulates the Resting State EEG on Alpha and Beta Bands.

Long-term evolution (LTE) wireless telecommunication systems are widely used globally, which has raised a concern that exposure to electromagnetic fields (EMF) emitted from LTE devices can change human neural function. To date, few studies have been conducted on the effect of exposure to LTE EMF. Here, we evaluated the changes in electroencephalogram (EEG) due to LTE EMF exposure. An LTE EMF exposure system with a stable power emission, which was equivalent to the maximum emission from an LTE mobile phone, was used to radiate the subjects. Numerical simulations were conducted to ensure that the specific absorption rate in the subject’s head was below the safety limits. Exposure to LTE EMF reduced the spectral power and the interhemispheric coherence in the alpha and beta bands of the frontal and temporal brain regions. No significant change was observed in the spectral power and the inter-hemispheric coherence in different timeslots during and after the exposure. These findings also corroborated those of our previous study using functional magnetic resonant imaging.