Sharif Digital Repository

Subcutaneous needle insertion is one of the key methods of limited invasive surgery in medical diagnosis and treatment. However, errors in needle targeting can reduce the effectiveness of such efforts. One of the main factors of errors is due to the human guidance of the needle, which many researches have approached in recent years, and among the suggested solutions is the use of automatic or semi-automatic assist systems. Considering the treatment of prostate cancer by brachytherapy method, this research has developed a semi-automatic physician assistance system using navigation based on the potential field method and ultrasound images of the needle location, and sliding mode fuzzy... 

Physiotherapy is a major part of the rehabilitation process that is used to retrieve patients' physical ability. The recuperation feedback in the physiotherapy process has a twofold significance for both physiotherapists and patients. It helps patients regain their ability to recover more quickly, prevent recurrence of injury to the treated area and other areas, and motivate the patient to continue treatment. It also helps the physiotherapist to monitor the process of rehabilitation and ensure the correctness of the procedure. Meanwhile, many patients cannot maintain continuous workouts due to lack of access to the physiotherapist at home and inability to provide required feedback.In this... 

Ability to speak lucidly plays a key role in social relations. Consequently the role of larynx is quite important and timely diagnosis of laryngeal diseases has proved to be crucial. Since conventional diagnostic methods of the larynx are usually expensive or bothersome, the aim of this project is to analyze and classify diseases of the larynx with the aid of signal processing which tend to be faster and easier to implement and quite economical. This study utilizes the vowel sound /a/ and a well referenced database, namely MEEI (Massachusetts Eye and Ear Infirmary) which includes 53 normal and 213 abnormal voices in 7 classified diseases. In this work, using existing signal modeling and... 

Conventional MRI has been used to diagnose different types of brain injuries. However these methods have generally failed to diagnose mild types of injury. We are working on the specification of mild traumatic brain injury, using diffusion MRI data, based on a multi compartment simulation of white matter tissue. This effort is essential for better understanding of underlying tissue micro-structure changes in patients with trauma. Some studies have been used in similar data fitting approaches in order to estimate axon diameter distribution. Specifically, a comparative study between different Compartment Models has shown that “ActiveAx” model has the best agreement with underlying tissue... 

Motor imagery causes Event related Synchronization/Desynchronization (ERS/ERD) in Electroencephalogram (EEG) signal. These potentials can be used as an input for a Brain Computer Interface (BCI) system. To do so, it is necessary for these inputs to be correctly classified. The quality of classification is severely affected by the features extracted. Common Spatial Patterns (CSP) algorithm is often used for this task. Some of this method disadvantages are neglecting non-stationary properties of EEG signal and its proneness to overfitting. Additionally, its success is highly dependent on the frequency band that the algorithm is performed in. The most suitable sub band is interchangeable... 

Learning disability (LD) is a neurological condition that interferes with an individual’s ability to store, process, or produce information. There are different types of learning disabilities affecting reading, writing, speaking, spelling, etc. Based on a study conducted by National Center for Learning Disabilities, 2.4 million American public school students are diagnosed with learning disability. They attend school in order to learn and be successful while they do not know their learning process is different from their peers. LD diagnosis in children is especially important as such cases must be identified early enough in order to provide them with proper education.This project targets LD... 

In many modern medical procedures, needle insertion is an inevitable part of the diagnosis or treatment protocols. The accuracy of the needle insertion is adversely affected by a number of factors. A needle, frequently assumed to be flexible, is inserted into a soft tissue and induces complex mechanical interactions that may result in considerable uncertainties. Tissue intrinsic characteristics as well as its deformation and rotation may cause dramatic complexities. This work considers the needle movement inside the tissue from the dynamics and control point of view. The proposed approach can be regarded as an initial step towards automation of needle insertion procedures; it can also be... 

Continuous and non-invasive blood pressure (BP) measurement systems generally utilize applanation tonometry and vascular unloading. Some of them satisfies the AAMI standards (|mean|<5, |SD|<8). Unfortunately they are hardly to be widely affordable due to the complicated mechanical structure and high production cost. Till now those devices are seldom being used in operation room and generally used in clinical researches. In 2000, a linear model using pulse transit time (PTT) to continuous and non-invasive blood pressure (BP) measurement was proposed. Due to the nonlinear performance parameters of the arteries, researchers have used nonlinear models to promote this method. Although the... 

Flow Mediated Dilation (FMD) is a non-invasive method for endothelial function assessment providing an index extracted from ultrasonic B-mode images. Although utilized in the research community, the difficulty of its application and high cost of ultrasonic device prevent it from being widely used in clinical settings. In this study we show that substituting the ultrasonic device with more easily handled and low cost photoplethysmography and electrocardiography is possible. We introduce new indices based on the photoplethysmogram (PPG) and electrocardiogram (ECG) and show that they are correlated with the ultrasound-based FMD index. To this end, conventional ultrasound FMD test was carried... 

Neural modeling is a branch of cognitive science in which the behavior of the nervous system is described through a collection of mathematical relations. By using these models, it is possible to study certain features of the networks or predict brain responses to different stimuli. One of the important features in neural networks is the adaptation phenomena that occurs in different forms. All types of adaptation occur in presence of a constant stimuli through a set period of time. Adaptation causes a departure from the stable pattern of neural activities which makes the responses unpredictable. Hence, it is important to study the effects of adaptation on the network activities.This study... 

Dnase I Hypersensitive Sites (DHSs) are known as comprehensive markers of DNA regulatory elements. The main function of regulatory elements is repressing or enhancing transcription of genes. Hence, the recruitment of the data is prevalent in many studies of genome. One of the applications of this data is to utilize it to predict active regulatory regions (Transcription Factor Binding Sites).There are different means to do this, divided in three major groups: first, the methods only use the number of DNase-seq reads that surround a candidate binding site. While robust, these methods do not reflect the shape of the signal. A second strategy uses a variety of approaches to model and identify... 

The human heart is a complex system that contains many clues about its function in its electrocardiogram (ECG) signal. Due to the high mortality rate of heart diseases, detection and recognition of ECG arrhythmias is essential. The most difficult problem faced by ECG analysis is the vast variations among morphologies of ECG signals. In this study, we propose an approach for y detection of abnormal beats and data visualization with respect to ECG morphologies by using manifold learning. In order to do so, a nonlinear dimensionality reduction method based on the Laplacian Eigenmaps is used to reduce the high dimensions of the ECG signals, followed by the application of Bayesian and FLDA method... 

Extensive studies have been performed on the genetic variations involved in common neurodegenerative diseases such as Alzheimer's, macular degeneration, and Parkinson's. In most cases, no specific gene has been identified pointing to a distinct pathogenic pathway, therefore, this study mainly aims to find common genes among aforementioned diseases according to determination of a specific pathogenic protein pathway.In this study, we reached a deep understanding of the function of nervous system and the discovery of causative agents of the diseases by applying the sources of information from genome datasets in bioinformatics analysis. The utilized database comprises the classification of... 

With technological advances in fabrication and control of prosthesis and assistive devices the importance of such systems has increased drastically. On the other hand the appropriate coupling of these devices, especially the exoskeletal systems with the upper or lower extremities is of immense importance as it is an integral part of the control system. In particular, the control strategy and its ability to adapt the exoskeletal system with the existing and physiological functionality of the user, is an integral part of the system requirement. In the controller implementation, a number of methods are proposed including using the excitation signal, similar to the existing neuromuscular system.... 

Wireless area body networks (WBANs) are a set of sensors designed to monitor an individual’s health remotely. These networks are required to transfer the data properly to the healthcare professional. Since there is no guarantee that no faults might occur, these networks should have fault tolerance capability such that they can maintain their main function properly. In this thesis, a method for fault tolerance in WBANs is proposed.In this research, to test the proposed method, a case study on sleep apnea disorder is selected for monitoring patients who experience sleep apnea. To this end, the Apnea-ECG dataset from the PhysioNet repository was considered which contains five different types of... 

Heartbeat is the result of contractions of over 10 billion cardiac cells. These cells’ cytoplasms are connected to each other by gap junctions which are arrays of intercellular protein channels. Thus action potential can propagate from one cell to another and cause its contraction. In core-conductor model, one-dimensional microscopic representation of cardiac tissue, cells are attached to each other to form a ladder network. The parallel elements are connected to each other by series resistors which represent gap junctions. These resistors are nearly always considered as static elements. In this thesis I have investigated the effects of incorporating the dynamicity of gap junction resistors... 

Identifying and interpreting standard fetal plates in first trimester examinations with two-dimensional ultrasound is a very complex task that requires years of experience. Aside from the challenge to position and direct the probe to required positions, there is an understandable difficultly for inexperienced sonologists to identify the corresponding structures in the emerging images. Automated image processing can be helpful both to the experienced as well as inexperienced operators to confront these challenges. In this study, we used data from three different devices SAMSUNG WS80A, VOLUSON E6, VOLUSON E8, which includes a total of 2230 images to measure the thickness of the space behind... 

Ultrasound imaging is one of the most widely used diagnostic methods in medicine due to its safety, cost-effectiveness and small and portable size of equipment. In this imaging method, line-by-line scanning is used to create the image, which has limitations in speed and resolution. To deal with these limitations, new methods have been proposed, such as plane-wave imaging with the possibility of increasing the imaging speed and synthetic apertures with the possibility of increasing the quality of images. By combining these two methods, high quality and speed can be achieved simultaneously. Therefore, in this research, based on previous studies, a number of elements were activated each time,... 

Tinnitus is understood to be a repeating sound, often in the form of a ringing in one or both ears, in the absence of any external stimulus. There is no definite scientific justification for this condition, but this complication usually occurs due to hearing loss or after aging or acute trauma. A recent community-based epidemiological study found that 17.5% of 60-year-olds and older were suffering from Tinnitus. Despite the significant outbreak and the great impact of this impairment on the quality of life of people with this condition, no definitive treatment has been provided so far. Therefore, further research in this field is of great importance. One of the tools used to carry out these... 

In recent years, steering percutaneous needle insertions with the aid of soft tissue modeling techniques has been of great interest. In this thesis an optical flow based motion estimation method is used to estimate tissue deformation. It also addresses needle tracking in ultrasound images for prostate biopsy and brachytherapy. The thesis reviews reported methods on needle insertion using ultrasound imagery and further introduces a projection based method (Hough Transform) for needle tracking. Considering that ultrasound images have releatively low contrast and high speckle noise content, diffusion and wavelet-based filtering methods are employed as noise reduction techniques. Next, an...