Biomedical Engineering and Bioengineering Commons^™

Performance Characteristics Of A Therapeutic Ultrasound Wire Waveguide, Graham Gavin, Garrett Mcguinness, Finbar Dolan, M.S. Hashmi

Articles

Therapeutic ultrasound angioplasty has been investigated, clinically, by a number of researchers and represents a potentially promising therapy for the treatment of atherosclerotic lesions. To date, there has been no detailed analysis of the effect of mechanical design parameters, such as wire geometry or damping characteristics, on wire waveguide performance. An apparatus capable of delivering therapeutic ultrasound down small diameter nickel–titanium (NiTi) wire waveguides is described. The output peak-to-peak (p–p) displacements at the distal tip of a 1.0mm diameter waveguide were measured experimentally, by means of an optical microscope and image analysis software. The output was measured for a range …

Application Of Advanced Computational Modelling In The Comparison Of Stent Induced Coronary Flow Disturbances, Jonathan Murphy, Fergal Boyle

Conference Papers

Coronary stent implantation can improve blood flow in an artery narrowed by the build up of arterial plaque. However, the haemodynamic effect of stent placement is unclear and may influence arterial restenosis (re-blockage). In this investigation computational fluid dynamics (CFD) was used to predict the non-Newtonian three-dimensional flow field in a coronary artery following implantation of two different stents. A graphical illustration of the stented areas affected to various degrees of wall shear stress (WSS) is presented for both the Palmaz-Schatz (PS) and the Gianturco-Roubin-II (GR-II) coronary stents. The axial WSS and wall shear stress gradient (WSSG) is also presented …

Evaluation Of Stent Design Based On The Haemodynamic Effect Of Coronary Stenting, Jonathan Murphy, Fergal Boyle

Conference Papers

No abstract provided.

Medical Rehabilitation Robotics, David Kennedy, Philip Deering, James Conlon

Conference Papers

Robotic Rehabilitation is a novel field of bio engineering combining precise mechanical design with control technology through the interaction of Medical and Engineering professionals to produce a new tool in medical rehabilitation. Paralysis is one of the common symptoms of a stroke sufferer; a medical condition causing weakness in one side of the body. It is treatable with a course of physiotherapy and Interactive Robotics can greatly accelerate this recovery. Although Robotic Rehabilitation is a relatively new technology its benefits are well recognized. The objective of this research work was to develop an interactive robot for the medical rehabilitation of …

Transfer Function Modelling: A Student-Centred Learning Approach, Aidan O'Dwyer

Conference papers

Traditionally, the modelling of real systems in engineering, using transfer functions, has been done in a mathematically intense manner. However, non-traditional learners such as mature students, part-time students and students without a conventional second-level educational background may not have strong mathematical foundations; in addition, all students increasingly expect technical work which is practical and which motivates independent learning. This paper reports on, reflects on and evaluates an innovative experiment developed by the author to estimate a transfer function model of a person’s eye-brain-hand motor response. In the experiment, carried out using a PC with data acquisition capability, the person is …

Application Of Advanced Computational Modelling In The Numerical Prediction Of The Haemodynamic Impact Of Coronary Stent Implantation, Jonathan Murphy, Fergal Boyle

Conference Papers

Coronary stent implantation can improve blood flow in an artery narrowed by the build up of arterial plaque. However, the haemodynamic effect of stent placement is unclear and may influence arterial restenosis (re-blockage). In this investigation the stent induced, non-Newtonian blood flow disturbances have been captured in a three dimensional computational domain. The results clearly show areas of low wall shear stress proximal and distal to the stent wires, a characteristic which is known to encourage restenosis. Furthermore, this computational method of observing the complex haemodynamics of the stent environment can be used in conjunction with medical trial data to …

The Effect Of Physiological Cyclic Stretch On The Cell Morphology, Cell Orientation And Protein Expression Of Endothelial Cells, V. Barron, Claire Brougham, K. Coghlan, C. Stenson-Cox, D. O'Mahoney, P.E. Mchugh

Articles

In vivo, endothelial cells are constantly exposed to pulsatile shear and tensile stresses. The main aim of this study was to design and build a physiological simulator, which reproduced homogenous strain profiles of the tensile strain experienced in vivo, and to investigate the effect of this cyclic tensile strain on the cell morphology, cell orientation and protein expression of endothelial cells. The biological response of human umbilical vein endothelial cells to a uniaxial cyclic stretch, in this newly developed simulator, was examined experimentally using immunohistostaining and confocal imaging and it was

found that the cells elongated and oriented at 58.9± …

Preliminary Results For A Monocular Marker-Free Gait Measurement System, Jane Courtney, Annraoi Depaor

Articles

This paper presents results from a novel monocular marker-free gait measurement system. The system was designed for physical and occupational therapists to monitor the progress of patients through therapy. It is based on a novel human motion capture method derived from model-based tracking. Testing is performed on two monocular, sagittal-view, sample gait videos – one with both the environment and the subject’s appearance and movement restricted and one in a natural environment with unrestricted clothing and motion. Results of the modelling, tracking and analysis stages are presented along with standard gait graphs and parameters.

Cutting Rate Effect On Temperature During Cortical Bone Sawing, Hamid Khalili Parsa, Ger Reilly, Brendan Mccormack

Conference Papers

When bone is cut the occurrence of thermal damage to the bone is of major concern to the surgeon. If the temperature exceeds 44°C for longer than 1 min, bone repair is impaired (Eriksson et al, 1984) and necrosis may occur. Repeated use of cutting blades may reduce the cutting efficiency (Wevers et al, 1987; Toksvig-Larsen et al, 1992). Wevers et al also found that there is a greater force required to cut cortical bone using a blunt saw compared to new one.

Indentation Fracture Of Bovine Cortical Bone: Acoustic Emission Technique, Ashkan Safari, Ger Reilly, Brendan Mccormack

Conference Papers

Indentation cutting may result in microcracking and main crack growth which was previously reported. In this study, we recorded the AE signals produced by cracking processes during cutting on cortical bone, measuring the cutting force and correlating between load-displacement curves and AE activities.

Controlled Braking Scheme For A Wheeled Walking Aid, Eugene Coyle, Aidan O'Dwyer, Eileen Young, Kevin Sullivan, A. Toner

Conference papers

A wheeled walking aid with an embedded controlled braking system is described. The frame of the prototype is based on combining features of standard available wheeled walking aids. A braking scheme has been designed using hydraulic disc brakes to facilitate accurate and sensitive controlled stopping of the walker by the user, and if called upon, by automatic action. Braking force is modulated via a linear actuating stepping motor. A microcontroller is used for control of both stepper movement and for supervisory control. An encoder is used to supervise walker movement in terms of time, distance and speed.

A Numerical Acoustic Fluid-Structure Simulation Of Therapeutic Ultrasound Angioplasty, Graham Gavin, Finbar Dolan, M.S J. Hashmi, Garrett Mcguinness

Conference Papers

INTRODUCTION Therapeutic ultrasound angioplasty is the delivery of high amplitude ultrasonic displacements to the distal-tip of small diameter wire waveguides with the goal of disrupting atherosclerotic plaques. This is a minimally invasive procedure that may have potential' in the treatment of complicated chronic total occlusions. The disruption of plaque is due to direct contact ablation and also cavitation, pressure waves and acoustic streaming in the fluid surrounding the vibrating waveguide distal-tip [1]. Cavitation appears to play a major role and some authors have suggested that plaque ablation is only evident above the cavitation threshold [2]. Makin and Everbach [3] performed …

A Numerical Acoustic Fluid-Structure Model Of A Therapeutic Ultrasound Angioplasty Device, Graham Gavin, M.S. J. Hashmi, Finbar Dolan, Garrett Mcguinness

Conference Papers

Ultrasonic angioplasty involves the use of ultrasonic vibrations delivered to the distal-tip of small diameter wire waveguides and is an emerging technology the may have potential use in the treatment of complicated atherosclerotic plaques during cardiovascular surgery. Complicated plaques, including chronic total occlusions and calcified lesions, seriously reduce success rates during standard intervention involving guidewire access, followed by balloon dilation or stent delivery. The large amplitude (0-150 μm) wire waveguide distal-tip displacements in the low-frequency ultrasonic (18-45 kHz) range have been shown to disrupt plaque material by direct contact ablation and cavitation, acoustic streaming and pressure wave components in adjacent …

Synthesising Life-Sciences And Control Engineering: An Outline Survey And A Practical Example, Aidan O'Dwyer

Conference papers

There is an increasing interest in life science related areas in the electrical and control engineering community [1]. One manifestation of this interest is the development of interdisciplinary programmes, such as the B.Sc. in Medical Physics and Bioengineering, offered by the Dublin Institute of Technology from September 2005. A significant amount of research work in control engineering has focused on aspects of human physiological system, for example blood glucose regulation [2], cardiovascular modelling and control [3], and limb control [4]. There is an increasing emphasis on interdisciplinary research; in recognition of this, the Institute of Electrical Engineers (IEE) has starting …

Analysis Of Indentation Loading Of Cortical Bone Using Acoustic Emission Techniques, Ashkan Safari, Ger Reilly, Brendan Mccormack

Conference Papers

In this study, we recorded the number of Acoustic emission (AE) hits and related AE energy during indentation fracture of cortical bone using a PAC PCI-2 card and pico sensor. A threshold value of 43dB was used to filter premature trigger due to background noise. Registered AE hits had more than one count (threshold crossing). Amplifier gain was set at 40dB with a (0.1-1) MHz band pass filter. 8mm cubes of cortical bones were indented in the longitudinal direction at constant crosshead speed of 1 mm min-1 using a large 2D, 50˚ wedge indenter. We hypothesised that signals occurring as …

An Experimental Technique For Measurement Of Heat Generated During Bone Sawing, Hamid Khalili Parsa, Ger Reilly, Brendan Mccormack

Conference Papers

Orthopaedic bone cutting processes such as osteotomy and hip arthroplasty involve the cutting of one with the aid of various manual and powered cutting instruments including manual and powered bone saws. The extent of surgically induced bone necrosis at the point of the cutting tool and the bone is mainly due to the frictional heat generated by bone cutting. Bone necrosis has an impact on bone regeneration, and the rate of healing of the bone post operation. The threshold temperature for impaired regeneration of bone is in the range of 44°C to 47°C. Overheating also affects the sharpness life of …

Detection Of Microcracks During Bone Cutting Using Acoustic Emission Techniques, Ashkan Safari, Ger Reilly, Brendan Mccormack

Conference Papers

Surgeons may use a number of cutting instruments such as osteotomes and chisels to cut bone during operative procedures. The initial loading of cortical bone during the cutting process results in the formation of microcracks in the vicinity of the cutting zone with main crack propagation to failure occurring with continued loading; microcracking acts as a stimulus for main crack formation and has also been shown to occur during the propagation of the main crack. It has also been reported that Acoustic Emission (AE) is generated due to microcrack formation and crack growth, prior to, and during final fracture in …

Sequential Labelling And Acoustic Emission Analysis Of Damage Occurring In Cortical Bone During Indentation Cutting, Ger Reilly, Ashkan Safari, David Taylor, Brendan Mccormack

Conference Papers

When a surgeon uses a wedge shaped blade or an osteotome to cut cortical bone during an operative procedure the bone will fail by a process of microcracking and primary crack propagation. It has previously been observed that crack propagation is dependent on the direction of cutting relative to the main axis of the bone. It has also been observed that microcracks occurring during fracture release acoustic signals that facilitate real-time monitoring of a cutting process. In these novel studies, we labelled damage accumulation during cutting of cortical bone using sequential chelating dyes and we correlated recorded AE signals during …

Electromagnetic Measurement Of Spinal Curvature, Ronan Fitzmaurice, Ted Burke, Annraoi De Paor

Conference Papers

In this paper, we describe an original mathematical technique for calculating the position and orientation of an electromagnetic coil from a minimum of four collinear magnetic field measurements. This problem arose in the development of a system for evaluating the efficacy of inflatable back rafts designed to mitigate complications that arise from the immobilisation of patients with suspected spinal injuries on spinal boards during transport to hospital. Electromagnetic markers are attached to points of interest on the back of an immobilised test subject. Spinal curvature is then measured by passing a magnetometer underneath the board.

An Investigation Of The Heat Affected Zone In Cortical Bone Sawing, Hamid Khalili Parsa, Ger Reilly, Brendan Mccormack, Andrew Macey

Conference Papers

Surgical procedures such as osteotomy and hip replacement involve the cutting of bone with the aid of various manual and powered cutting instruments including manual and powered bone saws. Frictional rubbing between the blade of the saw and the bone results in the generation of localised heating of the cut bone and increased cutting forces (Ark et al, 1997). Overheating in localised areas can cause bone necrosis and have an impact on the rate of healing of the bone post operation and overheating also affects the sharpness life of the blade. A review of the literature indicates that work has …

Development And Performance Characteristics Of An Ultrasound Angioplasty Device, Graham Gavin, Garrett Mcguinness, Finbar Dolan, M.S. J. Hashmi

Conference Papers

INTRODUCTION The effect of atherosclerosis is well documented and many procedures such as balloon angioplasty and stentimplantation have been developed to reopen occluded arteries. However, there are considerable differences in the material properties of various atherosclerotic lesions as they develop. Many authors have suggested that rigid calcified plaques may require specific procedures that target this rigid material through de-bulking or complete removal (Salunke et al, 1997). Ultrasound angioplasty is the delivery of high power low frequency ultrasound via a wire waveguide to the lesion location. This results in distal tip wire displacements of up to 100um peak-to-peak (p-p) at frequencies …

Experimental And Numerical Investigation Of Therapeutic Ultrasound Angioplasty, Graham Gavin, M.S. J. Hashmi, Garrett B. Mcguinness

Other resources

Therapeutic ultrasound angioplasty is an emerging minimally invasive cardiovascular surgical procedure that involves the delivery of ultrasonic displacements to the distal-tip of small diameter wire waveguides. The ultrasonic distal-tip displacements affect atherosclerotic plaque and thrombus by direct contact ablation, pressure wave components and cavitation, in addition to an acoustic streaming event around the distal-tip. This study uses experimental and numerical methods to investigate ultrasonic displacements in wire waveguides and the effect the distal-tip displacements have on the surrounding fluid. An experimental therapeutic ultrasound wire waveguide apparatus is described that delivers displacements to the distal-tip of 1.0 mm and tapered 0.35 …

An Acoustic Fluid-Structure Simulation Of A Theraputic Ultrasound Wire Waveguide Apparatus, Graham Gavin, M.S. Hashmi, Finbar Dolan, Garrett Mcguinness

Conference Papers

The use of high-power low-frequency ultrasound transmitted down small diameter wire waveguides is an emerging technology that may have potential in the treatment of complicated atherosclerotic plaques in cardiovascular surgery. This form of energy delivery results in vibrating the distal-tip of the wire waveguide disrupting material by means of direct contact ablation and also cavitation, pressure waves and acoustic streaming in the surrounding fluid. This work describes a numerical acoustic fluid-structure model of the ultrasound wire waveguide and blood surrounding the distal tip. The structural analysis of the model predicts the natural frequencies of the waveguide and shows the extent …

Techniques For Investigation Of Surgical Cutting Instruments, Eamon Price, Ger Reilly, Brendan Mccormack, Andrew Macey

Conference Papers

No abstract provided.

Direct Least-Squares Ellipse Fitting, Jane Courtney, Annraoi Depaor

Conference Papers

Many biological and astronomical forms can be best represented by ellipses. While some more complex curves might represent the shape more accurately, ellipses have the advantage that they are easily parameterised and define the location, orientation and dimensions of the data more clearly. In this paper, we present a method of direct least-squares ellipse fitting by solving a generalised eigensystem. This is more efficient and more accurate than many alternative approaches to the ellipse-fitting problem such as fuzzy c-shells clustering and Hough transforms. This method was developed for human body modelling as part of a larger project to design a …

Pressure Distribution Around Spherical Distal Ball-Tip In Ultrasound Angioplasty, Graham Gavin, Garrett B. Mcguinness, Finbar Dolan, M.S. J. Hashmi

Conference Papers

INTRODUCTION Ultrasound Angioplasty has been shown to be effective in the removal and re-canalising of blockages in arteries (Siegel RJ, 1993). By delivering therapeutic ultrasound to the blockage, via a wire waveguide to a ball-tip, the lesion or thrombus is affected by pressure waves, micro streaming, cavitation and direct contact with the oscillating ball-tip. Most work to date has concentrated on a spherical ball-tip geometry at the distal end of the wire waveguide (Steffen, 1994 and Rosenschein, 1996). Tip displacements usually lie between 10 - 100m (peak-to peak) and ball tip diameters between 1 - 2mm (Atar, 1999 and Yock, …

Simple Feature Identification And Matching For Stereoscopic Imaging, Jane Courtney, Annraoi Depaor

Conference Papers

Many camera calibration techniques used in stereoscopic imaging require corresponding points in image pairs to be identified. The best matches tend to come from very distinctive regions, hence it is preferable to use only these points and reject points from more homogeneous regions. Often points are selected and matched by a combination of user input and automated matching. However, for most techniques, the more matching points identified, the more accurate and robust the calibration. Therefore, it is desirable to alleviate the need for user input and to automate the point selection process. In the feature matching technique described here, a …

A Vocalisation-Based Drawing Interface For Disabled Children, Ted Burke

Articles

In our work with disabled children at Ireland’s National Rehabilitation Hospital, a problem we have experienced in the facilitation of art activities is that traditional art materials and standard computer drawing programs sometimes prove inaccessible. In this paper, an original system, called “PaintMyVoice” is presented which facilitates the creation of two or three-dimensional images using a variety of novel input modalities. In particular, vocalisations can be used to create original images of a variety of objects, including trees, flowers and landscape elements. Additional input to the system can optionally be provided via mouse, keyboard, switch interface or digital camera depending …

Mechano-Biological Interactions Of Endothelial Cells, Claire Brougham, Karen Coughlan, Valerie Barron, Peter Mchugh

Conference Papers

Atherosclerosis is an ever-increasing cause of morbidity in the western world. Current surgical treatments include bypass grafts and coronary artery stents. However, there is still a need for alternative approaches especially for those who cannot receive conventional therapy. Tissue engineering is one such approach that may hold the key to the repair and regeneration. Tissue engineering is one such approach that may hold the key to the repair and regeneration of coronary arteries. Nevertheless, many questions need to be answered before a vialbe vascular tissie with the inherent properties of native tissue becomes a real contender with the surgical therapies …

Development Of A Numerical Model To Simulate Pressure Distributions In Ultrasound Angioplasty, Graham Gavin, Garrett Mcguinness, Finbar Dolan, M.S. Hashmi

Conference Papers

Ultrasound Angioplasty has been shown to be effective in the removal and re-canalising of blockages in arteries (Siegel RJ, 1993). The ultrasound is delivered via a wire waveguide to the lesion location. The wire, generally, has a ball-tip at the distal end to increase transmission of the ultrasound to the surrounding fluid by causing the ball-tip to oscillate between 20– 45kHz and with displacements of up to 100mm peak-to-peak (Atar, 1999 and Yock, 1997). Pressure waves, micro streaming, cavitation and direct contact with the oscillating ball-tip affect the blockage. Most work to date has concentrated on a spherical ball-tip geometry …