فهرست مطالب

  • Volume:11 Issue: 2, 2014
  • تاریخ انتشار: 1393/05/22
  • تعداد عناوین: 8
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  • Neda Jahangiri, Alireza Bahrampour, Majid Taraz Pages 224-232
    This article reviews the development of non-invasive optical techniques for determination of blood glucose concentrations in diabetic patients. Early diagnosis and daily management are essential for ensuring the healthy life of diabetic patients. The determination of blood glucose concentration with common devices involves the chemical analysis of blood samples, which are obtained by pricking the finger or extracting blood from the forearm. Pain, discomfort, and inconvenience, associated with current invasive methods, have necessitated the investigation of non-invasive measurement techniques. Non-invasive monitoring of blood glucose level offers several advantages, including absence of pain and biohazard materials, non- exposure to sharp objects, increased testing frequency and consequently, tighter control of glucose concentration. Considering these potential advantages commercialization of non-invasive glucose monitoring devices has become a subject of increasing interest. Several optical technologies have the potential to provide viable non-invasive measuring devices. this review study aimed to describe the major optical technologies for non-invasive glucose monitoring and compare their advantages and disadvantages. second scenario) better than other methods in presence of a typically low false positive rate equal to 3%.
    Keywords: Diabetes, Glucose, Non, invasive, Optical techniques
  • Ali Akbar Akbari, Mahdi Talasaz Pages 233-241
    Introduction
    In order to improve the quality of life of amputees, biomechatronic researchers and biomedical engineers have been trying to use a combination of various techniques to provide suitable rehabilitation systems. Diverse biomedical signals, acquired from a specialized organ or cell system, e.g., the nervous system, are the driving force for the whole system. Electromyography(EMG), as an experimental technique,is concerned with the development, recording, and analysis of myoelectric signals. EMG-based research is making progress in the development of simple, robust, user-friendly, and efficient interface devices for the amputees.
    Materials And Methods
    Prediction of muscular activity and motion patterns is a common, practical problem in prosthetic organs. Recurrent neural network (RNN) models are not only applicable for the prediction of time series, but are also commonly used for the control of dynamical systems. The prediction can be assimilated to identification of a dynamic process. An architectural approach of RNN with embedded memory is Nonlinear Autoregressive Exogenous (NARX) model, which seems to be suitable for dynamic system applications.
    Results
    Performance of NARX model is verified for several chaotic time series, which are applied as input for the neural network. The results showed that NARX has the potential to capture the model of nonlinear dynamic systems. The R-value and MSE are and, respectively.
    Conclusion
    EMG signals of deltoid and pectoralis major muscles are the inputs of the NARX network. It is possible to obtain EMG signals of muscles in other arm motions to predict the lost functions of the absent arm in above-elbow amputees, using NARX model.
    Keywords: Electromyography, Above, Elbow Amputation, Recurrent Neural Network, Signal Prediction
  • Farve Daneshvar Fard, Sahar Moghimi, Reza Lotfi Pages 242-252
    Introduction
    Pressure ulcers are tissue damages resulting from blood flow restriction, which occurs when the tissue is exposed to high pressure for a long period of time. These painful sores are common in patients and elderly, who spend extended periods of time in bed or wheelchair. In this study, a continuous pressure and temperature monitoring system was developed for pressure ulcer prevention.
    Materials And Methods
    The monitoring system consists of 64 pressure and 64 temperature sensors on a 40×50 cm2 sheet. Pressure and temperature data and the corresponding maps were displayed on a computer in real-time. Risk assessment could be performed by monitoring and recording absolute pressure and temperature values, as well as deviations over time. Furthermore, a posture detection procedure was proposed for sitting posture identification. Information about the patient’s movement history may help caregivers make informed decisions about the patient’s repositioning and ulcer prevention strategies.
    Results
    Steady temporal behaviour of the designed system and repeatability of the measurements were evaluated using several particular tests. The results illustrated that the system could be utilized for continuous monitoring of interface pressure and temperature for pressure ulcer prevention. Furthermore, the proposed method for detecting sitting posture was verified using a statistical analysis.
    Conclusion
    A continuous time pressure and temperature monitoring system was presented in this study. This system may be suited for pressure ulcer prevention given its feasibility for simultaneous monitoring of pressure and temperature and alarming options. Furthermore, a method for detecting different sitting postures was proposed and verified. Pressure ulcers in wheelchair-bound patients may be prevented using this sitting posture detection method.
    Keywords: Interface Pressure, Temperature Monitoring, Pressure Ulcer, Sitting Posture Identification
  • Ahad Ollah Ezzati, Seyed Rabi Mahdavi, Hossein Mousavie Anijdan Pages 253-259
    Introduction
    In this study, we aimed to calculate dose enhancement factor (DEF) for gold (Au) and iron (Fe) nanoparticles (NPs) in brachytherapy and teletherapy, using Monte Carlo (MC) method.
    Materials And Methods
    In this study, a new algorithm was introduced to calculate dose enhancement by AuNPs and FeNPs for Iridium-192 (Ir-192) brachytherapy and Cobalt-60 (Co-60) teletherapy sources, using the MC method. In this algorithm, the semi-random distribution of NPs was used instead of the regular distribution. Diameters were assumed to be 15, 30, and 100 nm in brachytherapy and 15 and 30 nm in teletherapy. Monte Carlo MCNP4C code was used for simulations, and NP density values were 0.107 mg/ml and 0.112 mg/ml in brachytherapy and teletherapy, respectively.
    Results
    AuNPs significantly enhanced the radiation dose in brachytherapy (approximately 60%), and 100 nm diameter NPs showed the most uniform dose distribution. AuNPs had an insignificant effect on teletherapy radiation field, with a dose enhancement ratio of 3% (about the calculation uncertainty) or less. In addition, FeNPs had an insignificant effect on both brachytherapy and teletherapy radiation fields. FeNPs dose enhancement was 3% in brachytherapy and 6% (about the calculation uncertainty) or less in teletherapy.
    Conclusion
    It can be concluded that AuNPs can significantly increase the absorbed dose in brachytherapy; however, FeNPs do not have a noticeable effect on the absorbed dose
    Keywords: Brachytherapy, Dose Enhancement Factor, Monte Carlo, Nanoparticle
  • Hajar Moradmand, Saeed Setayeshi, Alireza Karimian, Mehri Sirous Pages 260-269
    Introduction
    Breast cancer is one of the most common types of cancer among women. Early detection of breast cancer is the key to reducing the associated mortality rate. The presence of microcalcifications clusters (MCCs) is one of the earliest signs of breast cancer. Due to poor imaging contrast of mammograms and noise contamination, radiologists may overlook some diagnostic signs, specially the presence of MCCs. In order to improve cancer detection, image enhancement methods are often used to aid radiologists. In this paper, a new enhancement method was presented for the accurate and early detection of MCCs in mammograms.
    Materials And Methods
    The proposed system consisted of four main steps including: 1) image scaling;2) breast region segmentation;3) noise cancellation using a filter, which is sensitive to MCCs; and 4) contrast enhancement of mammograms using Contrast-Limited Adaptive Histogram Equalization (CLAHE) and wavelet transform. To evaluate this method, 120 clinical mammograms were used.
    Results
    To evaluate the performance of the image enhancement algorithm, contrast improvement index (CII) was used. The proposed enhancement method in this research achieved the highest CII in comparison with other methods applied in this study. The Validity of the results was confirmed by an expert radiologist through visual inspection.
    Conclusion
    Detection of MCCs significantly improved in contrast-enhanced mammograms. The proposed method could be helpful for radiologists to easily detect MCCs; it could also decrease the number of biopsies and reduce the frequency of clinical misdiagnosis. Moreover, it could be useful prior to segmentation or classification stages.
    Keywords: breast cancer, Image Enhancement, Wavelet Transform
  • Shahrokh Naseri, Mahdi Momen Nezhad, Zahra Hozhabri, Abbas Haghparast, Golestan Karami, Peyman Hejazi Pages 270-275
    Introduction
    In computed tomography (CT) technology, an optimal radiation dose can be achieved via changing radiation parameters such as mA, pitch factor, rotation time and tube voltage (kVp) for diagnostic images.
    Materials And Methods
    In this study, the brain, abdomen, and thorax scaning was performed using Toshiba 16-slice scannerand standard AAPM and CTDI phantoms. AAPM phantom was used for the measurement of image-related parameters and CTDI phantom was utilized for the calculation of absorbed dose to patients. Imaging parameters including mA (50-400 mA), pitch factor (1 and 1.5) and rotation time (range of 0.5, 0.75, 1, 1.5 and 2 seconds) were considered as independent variables. The brain, abdomen and chest imaging was performed multi-slice and spiral modes. Changes in image quality parameters including contrast resolution (CR) and spatial resolution (SR) in each condition were measured and determined by MATLAB software.
    Results
    After normalizing data by plotting the full width at half maximum (FWHM) of point spread function (PSF) in each condition, it was observed that image quality was not noticeably affected by each cases. Therefore, in brain scan, the lowest patient dose was in 150 mA and rotation time of 1.5 seconds. Based on results of scanning of the abdomen and chest, the lowest patient dose was obtained by 100 mA and pitch factors of 1 and 1.5.
    Conclusion
    It was found that images with acceptable quality and reliable detection ability could be obtained using smaller doses of radiation, compared to protocols commonly used by operators.
    Keywords: Computed Tomography (CT), Absorbed dose, Optimization
  • Zahra Ojaghi, Haghighi, Azin Alizadehasl, Atoosa Mostafavi, Hassan Moladoust, Nasim Naderi, Feridoun Noohi, Majid Maleki, Vahid Nikseresht Pages 276-283
    Introduction
    Left ventricular (LV) twist is believed to store potential energy and plays an important role in generating diastolic suction. Recent advances in echocardiography techniques have allowed quantification of LV twist. The aim of the present study was to compare LV twist and torsion in healthy human subjects determined by velocity vector imaging (VVI) and tissue Doppler imaging (TDI) at rest.
    Materials And Methods
    All volunteers (72 healthy subjects) underwent complete echocardiographic study and LV torsional parameters were assessed using VVI or TDI methods. LV rotation at apical and basal short-axis levels was calculated throughout cardiac cycle and LV twist was defined as net difference between rotation angles of the two levels. The LV torsion was calculated as the LV twist divided by the LV end-diastolic length.
    Results
    Twist degree was significantly lower in the VVI group than the TDI group (11.4±2.4º vs.14.1±3.0º, p<0.001), but when LV twist was normalized by LV end-diastolic length, there was no statistically significant difference between the two groups (1.9±0.7 º/cm vs. 2.1±0.6 º/cm, p=0.142).
    Conclusion
    Normalized LV twist or LV torsion values were comparable for both imaging techniques (TDI and VVI methods). Results suggest that these methods may be interchanged for serial assessment, but needs additional studies and preferably larger populations to confirm it.
    Keywords: Echocardiography, Left Ventricle, Torsion
  • Seyed Vahab Shojaedini, Masoud Heydari Pages 284-293
    Introduction
    The morphologic features of human sperms are key indicators for monitoring fertility problems in men. Therefore, automated analyzing methods via microscopic videos have become the most favorite policy in infertility treatment during the last decades.
    Materials And Methods
    In the proposed method, firstly a hypothesis testing framework was defined to distinguish sperms from background. Then, some regions were selected as candidates by minimization of the information distance between the original and processed images. Finally, the correct sperms were extracted from candidates using a watershed-based algorithm.
    Results
    The proposed, Watershed Segmentation Algorithm (WSA), Multi Structure Element Segmentation (MSES) and Dynamic Threshold Segmentation (DTS) algorithms achieve true positive rates of 96%, 84%, 81%, and 70%, respectively, versus typically 3% of false positive rate in semen specimens with high density of sperms. The true positive rates of 87%, 69%, 66%, and 52%, respectively, at the same false positive rate were obtained for the semen specimens with high density of sperms.
    Conclusion
    Results show that false positive rates of the proposed algorithm were at least 8% (in the first scenario) and 32% (in the second scenario) better than other methods considering the minimum acceptable true positive rate of 90%. Furthermore, it has been shown that the proposed algorithm extracted sperms at least 12% (in the first scenario) and 18% (in the second scenario) better than other methods in presence of a typically low false positive rate equal to 3%.
    Keywords: Entropy, Infertility, Microscopy, Semen, Spermatozoa