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Model nonlinear effect in ultrasound fields
Kulík, Tomáš ; Čech, Petr (referee) ; Rozman, Jiří (advisor)
The main topic of this diploma thesis is the modeling of nonlinear effects in ultrasonic fields. The work deals with application of finite difference method (FDTD) on the Westervelt equation and the subsequent creation of the model of ultrasonic fields in MATLAB. This thesis also includes theoretical analysis of ultra-acoustic and technical aspects of diagnostic ultrasonography. In addition, this document includes verification of theoretical assumptions by using created model.
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Analysis of Nonlinear Effects in Ultrasound Diagnostics
Čížek, Martin ; Hrazdíra,, Ivo (referee) ; Halámek, Josef (referee) ; Rozman, Jiří (advisor)
The model study of nonlinear effects in the ultrasound diagnostics is focused on developing and experimental verification of new computer algorithms for numerical modeling of the ultrasound field including nonlinear effects accompanying the ultrasound propagation in biological tissues. A theoretical analysis of nonlinearities in ultrasound propagation and their contribution to thermal and mechanical effects of diagnostic ultrasound applications was conducted. A numeric model of ultrasound propagating through a tissue model formed of a set of homogenous layers with defined physical parameters was developed in Matlab environment. The computation of ultrasound field spatial distribution is based on the angular spectrum method. For simulating of nonlinearities Burgers nonlinear wave equation is used. The resulting spatial distribution of the ultrasound field is described by the amplitudes of selected number of harmonic components of the acoustic pressure, by the mechanical index, by the harmonic distortion of the signal and by the spatial peak temporal average intensity of all considered components. The numerical model was experimentally verified using an unique ultrasound measurement system – the ultrasound measurement basin. The verified numeric model was used for assessing the veracity of mechanical index and tissue heating prediction during ultrasound applications in cases when the nonlinear effects are neglected in computations. The reliability of the mechanical index indicated by the diagnostic ultrasound instruments is also evaluated using the designed numeric model. The aim was to compare the indicated value usually obtained by derating the measurements in a water medium to the actual mechanical index present in the insonated tissue.
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Application of diagnostic methods for devices of streem-gas blok
Hübková, Ivana ; Ondroušek, Luděk (referee) ; Matoušek, Antonín (advisor)
This master´s thesis deals with problem of reliability of technical device in general a so there is explained bathtub curve, defects and malfunctions of devices and then there is a brief outline of reliability system. This thesis further briefly describes technical diagnostic and then there is performed the vibrodiagnostic measurements of selected pumps and ventilators in in heating plant Červený mlýn in Brno. Evaluation of their condition is done according to relevant standards. Further there was done a diagnostic of the steam traps through the ultrasound diagnostic. The last part of my thesis deals with the reliability of selected specific pumps in foregoing rating plant. There are showed reliability curves of selected pumps and elaboration of data from their long-term vibrations measurement.
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Model Study of Ultrasound Effects on Fetal Development
Jaroš, Josef ; Halámek, Josef (referee) ; Hrazdíra,, Ivo (referee) ; Rozman, Jiří (advisor)
The progress in ultrasound techniques goes hand in hand with increasing of diagnostic machine acoustic outputs. Ultrasound biological effects can adversely influence the development of human fetus. Recent studies of thermal effect on biological tissues are usually based on simulation of simple ultrasound transducers. The aim of this work is to build a flexible model of diagnostic system to simulate temperature increase during fetal development. Different types of ultrasound probes were used for generation of acoustic field with simulated piezoelectric element properties. Optimized linear and phased arrays were modeled with dynamic beam steering and focus. Computer simulations were concentrated on extreme conditions in obstetric ultrasonography and 3D tissue model was compared with real ultrasound probes measurements. To detect temperature increase, the bone tissue phantom was used. Results point out potential risks for fetus with diagnostic ultrasound probes. Based on the results of this work, practical recommendations increasing safety of obstetric examinations were drawn.
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Problematics of musculosceletal dysfunction and chains
Hofman, David ; Malá, Jitka (advisor) ; Kučerová, Ilona (referee)
This diploma thesis deals with functional disorders of the musculoskeletal system. It discusses the possible causing factors of these disorders, their manifestations on the body, diagnostics and the possibilities of influencing them. Since this is a very common phenomenon on the human body, I chose mainly the muscle, fascia and joint structure, which I explored and described in more depth. The experimental part of this work aims to demonstrate the possible impact of the intervention of the 1.-3. ribs and claviculosternal joint as described by Ludmila Mojžíšová on the muscles of the neck (m. scalenus anterior, medius and sternocleidomastoideus). To obtain results, I used the ultrasound examination of the diameter of these muscles and Visual analogue scale (VAS) to obtain pain values before and after the intervention using this method. Title: Problematics of musculoskeletal dysfunction and chains Objectives: The first goal of this paper is to collect currently recognized sources about musculoscletal functional disorders. I have described origins of this kind of problems, manifestation of these disorders and kinds of therapy. I've focused on functional disorders of muscle, fascia and joint. Second goal of this thesis is to evaluate a top-rated Prague rehabilitation school's method. Part of Prague...
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Problematics of musculosceletal dysfunction and chains
Hofman, David ; Malá, Jitka (advisor) ; Kučerová, Ilona (referee)
This diploma thesis deals with functional disorders of the musculoskeletal system. It discusses the possible causing factors of these disorders, their manifestations on the body, diagnostics and the possibilities of influencing them. Since this is a very common phenomenon on the human body, I chose mainly the muscle, fascia and joint structure, which I explored and described in more depth. The experimental part of this work aims to demonstrate the possible impact of the intervention of the 1.-3. ribs and claviculosternal joint as described by Ludmila Mojžíšová on the muscles of the neck (m. scalenus anterior, medius and sternocleidomastoideus). To obtain results, I used the ultrasound examination of the diameter of these muscles and Visual analogue scale (VAS) to obtain pain values before and after the intervention using this method. Title: Problematics of musculoskeletal dysfunction and chains Objectives: The first goal of this paper is to collect currently recognized sources about musculoscletal functional disorders. I have described origins of this kind of problems, manifestation of these disorders and kinds of therapy. I've focused on functional disorders of muscle, fascia and joint. Second goal of this thesis is to evaluate a top-rated Prague rehabilitation school's method. Part of Prague...
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Model Study of Ultrasound Effects on Fetal Development
Jaroš, Josef ; Halámek, Josef (referee) ; Hrazdíra,, Ivo (referee) ; Rozman, Jiří (advisor)
The progress in ultrasound techniques goes hand in hand with increasing of diagnostic machine acoustic outputs. Ultrasound biological effects can adversely influence the development of human fetus. Recent studies of thermal effect on biological tissues are usually based on simulation of simple ultrasound transducers. The aim of this work is to build a flexible model of diagnostic system to simulate temperature increase during fetal development. Different types of ultrasound probes were used for generation of acoustic field with simulated piezoelectric element properties. Optimized linear and phased arrays were modeled with dynamic beam steering and focus. Computer simulations were concentrated on extreme conditions in obstetric ultrasonography and 3D tissue model was compared with real ultrasound probes measurements. To detect temperature increase, the bone tissue phantom was used. Results point out potential risks for fetus with diagnostic ultrasound probes. Based on the results of this work, practical recommendations increasing safety of obstetric examinations were drawn.
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|
Analysis of Nonlinear Effects in Ultrasound Diagnostics
Čížek, Martin ; Hrazdíra,, Ivo (referee) ; Halámek, Josef (referee) ; Rozman, Jiří (advisor)
The model study of nonlinear effects in the ultrasound diagnostics is focused on developing and experimental verification of new computer algorithms for numerical modeling of the ultrasound field including nonlinear effects accompanying the ultrasound propagation in biological tissues. A theoretical analysis of nonlinearities in ultrasound propagation and their contribution to thermal and mechanical effects of diagnostic ultrasound applications was conducted. A numeric model of ultrasound propagating through a tissue model formed of a set of homogenous layers with defined physical parameters was developed in Matlab environment. The computation of ultrasound field spatial distribution is based on the angular spectrum method. For simulating of nonlinearities Burgers nonlinear wave equation is used. The resulting spatial distribution of the ultrasound field is described by the amplitudes of selected number of harmonic components of the acoustic pressure, by the mechanical index, by the harmonic distortion of the signal and by the spatial peak temporal average intensity of all considered components. The numerical model was experimentally verified using an unique ultrasound measurement system – the ultrasound measurement basin. The verified numeric model was used for assessing the veracity of mechanical index and tissue heating prediction during ultrasound applications in cases when the nonlinear effects are neglected in computations. The reliability of the mechanical index indicated by the diagnostic ultrasound instruments is also evaluated using the designed numeric model. The aim was to compare the indicated value usually obtained by derating the measurements in a water medium to the actual mechanical index present in the insonated tissue.
|
|
|
Application of diagnostic methods for devices of streem-gas blok
Hübková, Ivana ; Ondroušek, Luděk (referee) ; Matoušek, Antonín (advisor)
This master´s thesis deals with problem of reliability of technical device in general a so there is explained bathtub curve, defects and malfunctions of devices and then there is a brief outline of reliability system. This thesis further briefly describes technical diagnostic and then there is performed the vibrodiagnostic measurements of selected pumps and ventilators in in heating plant Červený mlýn in Brno. Evaluation of their condition is done according to relevant standards. Further there was done a diagnostic of the steam traps through the ultrasound diagnostic. The last part of my thesis deals with the reliability of selected specific pumps in foregoing rating plant. There are showed reliability curves of selected pumps and elaboration of data from their long-term vibrations measurement.
|
|
|
Model nonlinear effect in ultrasound fields
Kulík, Tomáš ; Čech, Petr (referee) ; Rozman, Jiří (advisor)
The main topic of this diploma thesis is the modeling of nonlinear effects in ultrasonic fields. The work deals with application of finite difference method (FDTD) on the Westervelt equation and the subsequent creation of the model of ultrasonic fields in MATLAB. This thesis also includes theoretical analysis of ultra-acoustic and technical aspects of diagnostic ultrasonography. In addition, this document includes verification of theoretical assumptions by using created model.
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