bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiation Therapy, Intensity Modulated
Authors: Grant Walter
Published: April 2006

In the past 10 years, a new methodology for delivering radiation to cancer patients has evolved. This process is known as intensity modulated radiation therapy (IMRT) and has become a dominant treatment scheme. The purpose of this article is to discuss the distinctive features of IMRT, including its relationship to the process of computed tomography (CT) in diagnostic radiology. Since the dose patterns delivered consists of non‐uniform radiation patterns, the process requires special modulators operating under computer control. Both types of modulators are discussed in detail as well as the different processes that can be used to achieve the desired intensity map. As proof of the wide acceptance of the IMRT scheme in radiation therapy, a new delivery system has evolved that is designed to treat any target in the body with IMRT by using a helical delivery system that delivers therapy radiation doses. This machine has a waveguide mounted on a diagnostic CT scanner ring, has the appearance of a diagnostic scanner, and is discussed in some detail. Finally, creation of the non‐uniform radiation fields is facilitated by the use of computers using optimization algorithms. There are different approaches and these are discussed.
Computer‐Assisted Detection and Diagnosis
Authors: Nishikawa Robert M.
Published: April 2006

Computer‐aided diagnosis (CAD) is defined as a diagnosis made by a radiologist who takes into account the output of a computerized analysis of a medical image. There are in general two different types of CAD schemes: one to locate suspicious regions in the image, computer‐aided detection (CADe) and another to classify a suspicious region into one of two or more classes, computer‐aided diagnosis (CADx). The goal of CAD is to improve the performance of radiologists, to reduce variation within and between radiologists, and to make radiologists more efficient. This article describes motivation for developing CAD, the basic principles, current issues in CAD research, and future areas for development.
Radiotherapy, Three‐Dimensional Conformal
Authors: Starkschall George
Published: April 2006

Three‐dimensional conformal radiotherapy (3DCRT) is a technique used in the treatment of malignant tumors in which the radiation dose distribution is designed to conform to the contours of a target volume, keeping radiation doses to the surrounding uninvolved anatomic structures to within acceptable limits. Key components of 3DCRT include imaging the patient and tumor in three dimensions; precisely defining the target volumes, accounting for demonstrable tumor as well as microscopic disease, and accounting for motion and setup uncertainty; designing treatment portals based on visualization of the target volumes; calculating radiation dose using sophisticated mathematical models that accurately reflect energy transport; and implementing an integrated program for verifying that the dose prescribed is appropriately delivered in the correct amounts to the correct points. Clinical studies demonstrated that the increased radiation doses allowed by 3DCRT have the potential for increasing the rate of control of malignant disease.
Skin Tissue Engineering for Regeneration
Authors: Harley Brendan A. , Yannas Ioannis V.
Published: April 2006

Skin wounds, particularly burns, affect a large population each year. The injury response to skin wounds depends both of the severity of the wound and the animal affected. The typical organismic response to an injury at the organ‐scale is cell‐mediated wound contraction and synthesis of nonphysiologic tissue (scar); this process is termed repair. Regeneration of lost or damaged tissue describes a process marked by synthesis of physiologic (normal, functional) tissue in the wound site. With increasing organism development, wound closure depends increasingly less on regeneration and correspondingly more on contraction and scar formation. A variety of tissue engineering constructs have been utilized to prevent contraction and scar formation and induce regeneration following skin wounds. Experimental experience has identified a number of specific criteria to maximize the bioactivity of such a graft, leading to maximal regeneration. These criteria as well as the morphology, functionality, and regenerative capacity of the three tissues that comprise skin will be detailed. In addition to the description of the organismic response to skin injuries and the current and historical clinical treatments for such injuries, five specific devices developed to treat severe skin injuries, including the design and manufacture of each device as well as the attendant experimental and clinical successes, will be detailed.
Statistical Methods
Authors: Delorme Arnaud
Published: April 2006

Statistics represents that body of methods by which characteristics of a population are inferred through observations made in a representative sample from that population. Since scientists rarely observe entire populations, sampling and statistical inference are essential. First, this article discusses some general principles for the planning of experiments and data visualization. Then, a strong emphasis is put on the choice of appropriate standard statistical models and methods of statistical inference. Standard models (binomial, Poisson, normal) are described. Application of these models to confidence interval estimation and parametric hypothesis testing are also described, including two‐sample situations when the purpose is to compare two (or more) populations with respect to their means or variances. Nonparametric inference tests are also described in cases where the data sample distribution is not compatible with standard parametric distributions. Resampling methods using many randomly computer‐generated samples are finally introduced for estimating characteristics of a distribution and for statistical inference. The following section deals with methods for processing multivariate data. Methods for dealing with clinical trials are also briefly reviewed. Finally, a last section discusses statistical computer software and guides the reader through a collection of bibliographic references adapted to different levels of expertise and topics.
Tactile Stimulation
Authors: Poletto Christopher J.
Published: April 2006

Tactile stimulators manipulate sensors in the skin to produce sensations such as light touch, vibration, pressure, shape, and texture. The wide variety of applications for tactile stimulation include sensory substitution and augmentation, telepresence and telerobotic sensory feedback, improved immersion in virtual environments, and general information communication through the skin senses. This article discusses the three primary classes of tactile stimulation technologies: vibrotaction, dynamic mechanical shape arrays, and electrocutaneous stimulation. An overview of basic mechanoreceptor physiology is provided, including implications for stimulator design parameters. Predictions for the future development of tactile stimulation are presented, including the emerging applications in wearable computers.
Tissue Engineering
Authors: Masters Kristyn S. , Murphy William L.
Published: April 2006

Tissue engineering is a rapidly emerging field that combines elements of biology, chemistry, engineering, and clinical medicine in order to develop a means of repairing or regenerating damaged organs and tissues. Tissue engineering strategies entail various combinations of cells, biomaterials, and bioactive molecules. This article provides an overview of the field of tissue engineering, including its principles, history, strategies, tools, and challenges.
Tomotherapy
Authors: Holmes Timothy , Mackie Thomas R.
Published: April 2006

Tomotherapy is a form of intensity‐modulated radiotherapy (IMRT) using a rotational fan‐beam delivery scheme. The term derives from
tomographic radiotherapy
, literally meaning “slice” radiotherapy. Two types of tomotherapy,
serial
and
helical
, have been developed and implemented clinically. Serial tomotherapy, embodied in the NOMOS Peacock System (NOMOS, Corp. Sewickley, PA) is an add‐on modality for conventional C‐arm medical linac gantries. Conversely, the Hi‐ART II helical tomotherapy system (TomoTherapy, Inc., Madison, WI) is a full function radiotherapy treatment machine built upon a helical computerized tomographic (CT) ring gantry that includes megavoltage CT imaging capability. Both tomotherapy implementations have a high level of system integration with common components being (a) an inverse treatment planning system, and (b) computer controlled beam modulation using a pneumatically driven multileaf collimator. The major difference between the two implementations is that the Hi‐ART II includes integrated CT imaging capability. This added capability is primarily used for daily image guidance of target location to improve precision and accuracy of IMRT treatments. In addition, the detector can be used for machine quality assurance, and for reconstructing daily estimates of delivered dose using measured profiles of X‐ray fluence transmitted through the patient during treatment delivery. This latter capability, called
dose reconstruction
is integral to the process of
adaptive radiotherapy
wherein a daily discrepancy between planned and delivered dose due to errors in patient setup or changes in gross tumor volume can be corrected in future treatments.
Ventilators, Acute Medical Care
Authors: Tamul Paul C. , Leonard Craig
Published: April 2006

A ventilator, like most critical care devices, is simply a machine. However, it is not a “simple machine.” Over the past five decades, the means of delivering gases to patients have become more complex. This has led to an evolution of more than 30 critical care ventilators being used in the United States. The numerous modes of ventilation and our unfortunate attempt to reach a consensus on the terminology used when referring to mechanical ventilation presents a challenge to even the most skilled clinician. Mushin’s description of ventilators in his archetypal text is appreciated by many and addresses the classification scheme that can be adopted to the less‐sophisticated mechanical ventilator. An innumerable count of authors has used this classification method when writing about mechanical ventilator support. Today’s mechanical ventilators are designed to provide life support using an array of computerized logic systems, software utilities, and even artificial intelligence models to deliver gas to patients. This evolution of ventilators has led to a modernistic classification system to describe todayrsquo;s microprocessor‐controlled mechanical ventilator. A classification system that is specific and well defined is intended to enhance communications between clinicians. However, some respected organizations and clinicians have been reluctant to accept this new system for understanding mechanical ventilation despite its acceptance by leading members in the pulmonary and critical care medicine community.
Visual Prostheses
Authors: Delbeke Jean , Veraart Claude
Published: April 2006

A visual prosthesis is an active implantable device intended to restore vision in a blind person. Present day systems are only partially implanted. A number of different approaches are under development. These are mainly classified on the basis of their interface to the visual nervous system. One particular approach resorts to chemical activation of the retina. All others use electrical stimulation applied subretinally, epiretinally, transretinally, to the optic nerve, on the visual cortex, or in the visual cortex. These systems can typically be described as a chain comprising a camera or image grabbing unit, a processor, a telemetry unit, an implanted stimulator and an implanted electrode. Localized phosphenes have been obtained and exploited to convey a primitive form of visual information to the brain. Feasibility has been demonstrated, but a clinical evaluation has yet to come. Many aspects of these devices are still open to rapid and significant development.
Stereotactic Surgery
Authors: De Salles Antonio A.F. , Gorgulho Alessandra
Published: April 2006

Stereotaxis allows the precise localization of a point in the space based on the mathematical model proposed by Renee Descartes, which is defined by three plans: X, Y and Z. This concept was first used in Neurosurgery by Clarke and Horsley, who applied a stereotactic frame in animals to guide electrodes into the depth of the cerebellum to study neuronal function. Not until 1947, Spiegel and Wycis performed the first stereotactic procedure in humans, which was a thalamotomy for psychiatric disorder. Different frame systems to localize a deep brain structure three dimensionally were proposed. The arc centered system, developed by Lars Leksell in 1949, became the most commonly used. The ventriculography was the first great step on the development of stereotactic surgery. It provided the indispensable brain landmarks for the neurosurgeon to start the electrophysiological brain mapping. Functional and anatomic atlases of the brain were developed to guide the stereotactic operations. The development of computadorized tomography (CT) and magnetic resonance images (MRI) improved the targeting since the anatomy visualization became more detailed. The stereotaxis frameless became possible through the use of Neuronavigation. Stereotactic surgery is widely applied for morphological and functional procedures in the brain. Examples of morphological applications are brain biopsies, guided craniotomies for tumor resection and radiosurgery. Functional applications are implant of deep brain stimulators (DBS) or ablative lesions for movement disorder, pain, psychiatric diseases and epilepsy. The real time imaging can be provided when the procedures are performed in the interventional MRI.
Microdialysis Sampling
Authors: Stenken Julie A.
Published: April 2006

Microdialysis samplin is a well knowin vivocollection method for low molecular weight hydrophilic analytes. This sampling method has its historical roots in the field of neuroscience since it is commonly used for collection of neurotransmitters. The successful application of microdialysis sampling for neuroscience applications has led to the expansion of the technique for collection of a wider range of analytes including drugs, metabolites, peptides and proteins. This article covers both the practical and theoretical aspects ofin vivomicrodialysis sampling. A brief comparison of the advantages and disadvantages of a fewin vivoanalysis methods versus microdialysis sampling is presented. The fundamental priciples of microdialysis sampling are disucssed with an emphasis on how analyte diffusive mass transport affects the recovery process during microdialysis sampling. This understanding of diffusive mass transport is especially critical during thein vivorecovery of larger peptides and proteins. Next, sample analysis challenges and needs are described since only low microliter volumes are obtained during the microdialysis sampling process. The many different types of analytical methods used for analyte quantitation are presented including immunoassays, sensors and separations methods. Both clinical and research applications of the technique are also described. Finally, a vision for the future of microdialysis sampling and recommendations for deveice and methodology improvement are proposed.
Minimally Invasive Surgery
Authors: Goldberg Jay R.
Published: April 2006

Minimally invasive surgery (MIS) is performed with small devices inserted through intact natural orifices or channels, or small incisions used to create an orifice. Some procedures are performed with devices located outside the body, and thus are noninvasive. The MIS procedures are an alternative to open surgery. The benefits of MIS include reduced patient trauma, postoperative recovery time, and healthcare costs.
Quality‐of‐life Measures, Clinical Significance of
Authors: Kamath Celia C. , Sloan Jeffrey A. , Cappelleri Joseph C.
Published: April 2006

This article defines clinical significance, as opposed to statistical significance, as it relates to health‐related quality of life measures used in clinical trials. It provides a brief history of the concept and addresses the different perspectives from which it is perceived and interpreted. It describes the current methods used to assess clinical significance and provides several examples of the different ways of measuring, validating, and using the concept of clinical significance. Recent developments on the concept are discussed. Finally, directions for future research are highlighted.
Accelerometers
Authors: Benson Lisa
Published: April 2006

Accelerometers are devices that measure acceleration and convert it to an electrical signal. The output is commonly in units of gravity (g). Most consist of some type of mass that accelerates and a sensor to measure its acceleration. They are mounted securely to the object being monitored in a way that limits damping of the acceleration signal. Accelerometers have been used in biomedical applications such as human motion analysis, motion detection vibration, and impact studies. As they are sensitive to acceleration caused by gravity, accelerometers can be used as tilt sensors, which measure the direction of an object relative to the ground. Applications of tilt sensors include sensing the onset of motion, biofeedback, and manipulation of handheld devices such as cell phones and wireless computer interfaces. Most accelerometers are based on semiconductor technology, and depending on device construction and properties, they can measure very small accelerations caused by vibration (micro g), or very large accelerations during motion or impact (thousands of g's). The performance capabilities of accelerometers have greatly improved over the past decade, due in part to advances in micro‐electromechanical systems (MEMS) technology. As these devices become smaller in size, it is likely that more widespread use in biomedical applications will occur in the future.
Cardiac Action Potentials
Authors: Demir Semahat S.
Published: April 2006

This article introduces the fundamental principles of cellular electrophysiology and focuses on cardiac cellular bioelectricity. The concepts of resting membrane potential, cardiac action potentials, and the ionic mechanisms are presented. The experimental techniques that are used to quantify ionic mechanisms in cells are described. Mathematical modeling of cardiac cells is introduced. Specifically, computational modeling of the murine ventricular action potentials is presented.
Adhesion of Cells to Biomaterials
Authors: Whitelock John M. , Melrose James
Published: April 2006

Proteins and glycoproteins from the extracellular matrix family of molecules, including those from the extracellular environment of plasma, are those that are adsorbed from biological fluids onto the surface of biomaterials. They affect and control the subsequent adhesion of cells from the surrounding environment, including those from circulation. Once adsorbed, their tertiary structure is altered, which affects the biological signals that they can deliver. One important and integral message that these molecules control is the adhesion of cells to biomaterial surfaces by interacting with a group of molecules on the cell surface called the integrins. They bind to specific amino acid sequences in extracellular matrix molecules and are a large family of transmembrane molecules, which are key components of cellular focal adhesions. The cytoplasmic extensions of the integrins interact with components of the cells cytoskeleton and are important in the determination of cell shape and signal transduction events, which can involve both out‐in and in‐out signaling and allows the cell to sense and respond to subtle alterations in its biomechanical micro‐environment. Such events are critical for the maintenance of the correct phenotype of the cell and the homeostatic balance of connective tissues. Specific cell‐binding sequences based on the peptide modules of cell attachment molecules have been determined and used to treat biomaterial surfaces to promote cellular attachment in applications such as vascular grafts and bioreactor surfaces.
Alumina
Authors: Standard Owen C.
Published: April 2006

Alumina (
α
‐Al
2
O
3
) is a ceramic oxide material that has been used as a biomedical implant material since the early 1970s in both high‐density, high‐purity polycrystalline and single crystal forms. The composition and microstructure of alumina are strongly dependent on the manufacturing processes used to make components and can profoundly influence the performance of the material in service. The purification and refinement of alumina powder and conventional ceramic fabrication routes used to manufacture alumina components are examined. The role of chemical composition and microstructure on the strength, fracture behavior, fatigue, and wear behavior of high‐density, high‐purity polycrystalline alumina are examined with specific reference to the use of this material in load‐bearing tribological applications in biomedical engineering. Regulatory requirements governing the use of alumina as an implant material, in particular the need for the ceramic to be fully dense and to have small grain size in order for it to be used reliably in total hip prostheses, are explained by consideration of the underlying materials science as well as the clinical demands in service. The biocompatibility of alumina, the use of osseous tissue ingrowth to stabilize prostheses in the skeletal system, and the application of polycrystalline alumina and sapphire in dental applications are also examined.
Bayesian Analysis
Authors: Williams Andy P. , Abbas Ali E.
Published: April 2006

Quantifying uncertainty has been a prime interest for centuries, essentially as far back as games of chance. Probability theory rose to prominence in the seventeenth century with the works of Blaise Pascal and others, addressing specifically the odds associated with a roll of a die. One question that grew out of such concerns was the following: Given the number of times an event has happened and failed, determine the chance that the probability of it happening in a single trial lies between two named probabilities.

The answer to that particular question was proposed in the eighteenth century by the Reverend Thomas Bayes, and the approach has taken his name in honor of the discovery. In general, Bayesian analysis refers to the process of assessing the current state of knowledge, gathering new data, and updating the analysis to incorporate both the prior (called so because it is prior to collecting anything other than the background information) assessment and the new data. The process has a wide range of applications including scientific inquiry, clinical testing, public policy, and developing new e‐mail spam filters. This article presents the fundamental concepts of Bayesian analysis and presents several applications for its use.
Bioacoustic Signals
Authors: Hadjileontiadis Leontios J. , Rekanos Ioannis T. , Panas Stavros M.
Published: April 2006

Biological sounds, such as lung sounds, heart sounds, bowel sounds, and joint sounds, emitted from the human body during its functioning provide an easy and noninvasive way of indicating existing pathology. By applying advanced signal processing techniques to the so‐called bioacoustic signals (BAS), useful information of high diagnostic value can be revealed. The purpose of this review is an in depth exploration of the properties of BAS, starting from their categorization, their characteristics and relation to human pathologies, and moving on to the recording standards that should be followed for their accurate acquisition, and focusing on the most current BAS analysis techniques. The latter refer to important signal processing issues, such as de‐noising, detection, modeling, feature extraction, and classification, involving a variety of methodologies, such as spectral analysis, wavelet transform, higher‐order statistics/spectrum, lower‐order statistics, fractal dimension, higher‐order crossings, reduced interference time‐frequency distributions. As a result, the way important problems in BAS analysis are approached with modern mathematical techniques is presented. Some descriptive examples along with an updated bibliography are provided to the reader as a means for thorough exploitation of BAS, because they cover advanced applications in the field. Consequently, the current pathways and trends in BAS analysis are introduced, giving rise to their objective evaluation and interpretation. However, they reveal the call for a common interest in interdisciplinary undertakings, both by biomedical engineers and by clinicians. Although it is unknown when traditional clinicians accept alternative approaches in everyday clinical practice, the results shown here are the outcome of joined efforts and scientific resources from both engineers and clinical medical doctors, paving the way for an accelerated transition from a traditional to a more enhanced analysis and appreciation of BAS.
Bioelectricity and Biomagnetism
Authors: Ueno Shoogo , Sekino Masaki , Ogiue-Ikeda Mari
Published: April 2006

This article reviews recent advances in biomagnetics and bioimaging techniques such as transcranial magnetic stimulation (TMS), electroencephalography (EEG), electromyography (EMG), magnetoencephalography (MEG), and magnetic resonance imaging (MRI). TMS is a method to stimulate neurons by eddy currents induced by a strong electric current, which is applied to a coil over the head. TMS is used for noninvasive mapping of the brain function, and has therapeutic effects on neurological and psychological diseases. EEG and EMG are techniques to record electric potentials at electrodes attached to the surface of the head and body, respectively. MEG is a method for measuring magnetic fields as weak as 5 fT by superconducting quantum interference devices (SQUID) arrayed on the scalp. MRI is a method to obtain spatial distribution of nuclear magnetic resonance (NMR) signals using gradient magnetic fields and Fourier transform. This article also reviews application of magnetic fields for cancer therapy and tissue engineering, and magnetoreception in animals.
Biomedical Sensors
Authors: Yeow John T.W.
Published: April 2006

This chapter is intended to be a brief yet broad introduction to biomedical sensors and their underlying sensing mechanisms. The topics covered in this chapter include the classification of sensors, their sensing principles and modalities, and future trends in biomedical sensing devices. Sensors that use electrical transducing effects, such as thermoresistive, thermoelectric, piezoelectric, photovoltaic, electromagnetic, and electrostatic, will not be discussed in detail. It is discussed in the chapter entitled “Biomedical Transducer.” The objective of this chapter is to equip the readers with a general knowledge of biomedical sensors.
Biometrics
Authors: Ma Ting , Zhang Yan , Zhang Yuang-Ting
Published: April 2006

Biometrics deals with the automatic recognition of individuals based on statistical analysis of physiological and/or behavioral characteristics. Any human physiological or behavioral characteristic that is unique, universal, stable, and collectable could be used as a biometric characteristic.

In the modern automated world, access to a reliable authentication system becomes increasingly essential. However, traditional authentication methods based on the user's exclusive knowledge, such as password, personal identification number (PIN), or something belonging to one, such as a cardkey, smart card, or token [like identity cards (ID)], can hardly meet the requirements of the reliability of an authentication system because passwords or PIN may be forgotten and ID cards can be lost, forged, or misplaced. Compared with traditional methods, biometrics can provide enhanced security and convenience. As biometric recognition systems are increasingly deployed for many security applications, biometrics and its applications have attracted considerable interests. Recently, biometrics has emerged as one of the most reliable technologies for future human identification and verification.
Bio‐Optics: Optical Measurement of Pulse Wave Transit Time
Authors: Meigas Kalju , Lass Jaanus , Kattai Rain
Published: April 2006

The arterial blood pressure has long been known as one of the most important medical factors reflecting the state of the cardiovascular system. A useful and convenient parameter for continuous monitoring of blood pressure is pulse wave velocity or pulse wave transit time (PWTT) between different regions of human body. It is suggested that, although it may be difficult to estimate systolic blood pressure from PWTT with acceptable accuracy, possibilities still remain to use changes of pulse arrival time as an indicator of changes in systolic blood pressure. During the exercise, arterial blood pressure increases, which is mainly achieved by increasing the contractility of the heart and vasculature resistance. Both of these values result in the increase of pressure wave speed in the vascular system, which means that the time delay between the start of electromechanical contraction and PWTT to any particular point in the body decreases. In our previous studies, we have shown that it is possible to calculate the mean arterial pressure from pulse wave transit time.
Extracorporeal Electrodes
Authors: Pullan Andrew J. , Nielsen Poul M.F. , Budgett David M.
Published: April 2006

Extracorporeal electrodes are, by definition, electrodes that are situated outside the body. In this article, we address the range and type of electrodes used in extracorporeal applications. The fact that these electrodes are remote from the biological electrical source whose activity is being measured means such electrodes face unique challenges. We discuss these challenges and, with this as our background, describe the types and properties of the different surface electrodes in use today.
Bone Resorption
Authors: Haynes David R. , Findlay David M.
Published: April 2006

Bone is continually being removed and replaced throughout life by the actions of osteoblasts (bone forming cells) and osteoclasts (bone resorbing cells). Bone loss in disease can be caused by either excessive bone resorption or decreased bone formation, or both. Recently, significant advances have been made in our understanding of the factors that regulate the formation and activation of the cell type in bone responsible for bone resorption, the osteoclast. Bone loss pathologies can be broadly divided into two types: systemic diseases, such as osteoporosis, in which bone is lost throughout the skeleton, and conditions characterized by more focal bone loss, such as the joint erosions in rheumatoid arthritis, tumor‐induced osteolysis, periodontal bone loss, and bone loss around orthopedic prostheses. Although the same molecules appear to be involved in bone resorption in health and disease, they appear to be expressed by different cell types, depending on the particular pathology concerned. This review of bone resorption discusses the current understanding of osteoclast formation and activity and the factors that are responsible for bone loss in various pathologies, with particular emphasis on bone loss in inflammatory conditions.
Cardiac Arrhythmia
Authors: Jordan Peter , Christini David
Published: April 2006

The term cardiac arrhythmia refers to any disturbance or perturbation to the normal electrical activation sequence of the heart. In this article, the basic electrophysiological mechanisms underlying tachyarrhythmias (abnormally fast heart rhythms) are discussed, and a number of commonly occurring tachyarrhythmias are reviwed. The main therapeutic modalities used to treat tachyarrhythmias are also summarized.
Cardiac Imaging
Authors: Santos Andres , Ledesma-Carbayo Maria J.
Published: April 2006

The aim of cardiac imaging is to contribute to the diagnosis of cardiac and vascular diseases by detecting early signs of abnormal activity, and to contribute to therapy follow‐up. Cardiac imaging attempts to detect global or local abnormalities in morphology, function, perfusion, and metabolism of the heart and vessels, including the evaluation of myocardial viability and artery plaques.

The main imaging modalities are presented here. X‐ray angiography is useful for assessing heart and vessel anatomy, although it is an invasive modality requiring catheterization. Echocardiography is a widespread, cheap, and non‐invasive modality that can analyze cardiac anatomy, tissue and blood motion, and perfusion. Traditionally, nuclear imaging with thallium or technetium has been used to detect myocardial perfusion defects. Recently, molecular imaging, using positron emission tomography, has been proposed to identify molecular processes like angiogenesis or apoptosis. Cardiac magnetic resonance imaging is attracting increasing interest as it can now produce high‐quality images with good spatial resolution. Apart from evaluating anatomy, it also allows assessment of tissue and blood motion, perfusion, and myocardial viability. Finally, ultrafast computed tomography may also produce high‐resolution images of the heart and great vessels, showing and characterizing their function and assessing plaques in coronary arteries.

As will be seen, currently available imaging modalities are complementary, showing different characteristics of cardiovascular structures and helping to achieve an accurate and early diagnosis of cardiovascular diseases.
Cardiac Valves
Authors: Hwang Ned H.C.
Published: April 2006

The article covers some historical investigation of mammalian heart. The basic anatomy and natural function of heart valves, heart valve disease, and its treatment with replacement prostheses are described. The FDA regulatory requirements of mechanical heart valves, biological prosthetic heart valves, and tissue engineered replacements are discussed.
Careers
Authors: Demir Semahat S.
Published: April 2006

According to the National Science Board, the most recent occupational projections from the Bureau of Labor Statistics (BLS) predict that the employment in science and engineering occupations will increase about three times faster than the overall growth rate for all occupations.

The Bureau of Labor Statistics (BLS) Occupation Outlook Handbook 2004–2005 presents that, by 2012, the future job growth will be in (1) health care and social assistance (increase by 32.4%) and (2) biomedical, biotechnology, and bioengineering (increase by 21–35%). Thus, promising career and job opportunities exist for biomedical engineers.
Articular Cartilage
Authors: Herzog Walter
Published: April 2006

Articular cartilage is a thin (about 1–6 mm in human joints) layer of fibrous connective tissue covering the articular surfaces of bones in synovial joints. It consists of cells (2–15% in terms of volumetric fraction) and an intercellular matrix (85–98%) with a 65–80% water content. Articular cartilage is a viscoelastic material and in conjuction with synovial (joint) fluid, allows for virtually frictionless movement (coefficients of friction from 0.002–0.05) of the joint surfaces. Osteoarthritis is a joint disease that is associated with a degradation and loss of articular cartilage from the joint surfaces and a concomitant increase in joint friction causing pain and disability, particularly in the elderly population. The primary functions of articular cartilage include force transmission across joints, distribution of articular forces so as to minimize stress concentrations, and provision of a smooth surface for relative gliding of joint surfaces. In most people, articular cartilage fulfills its functional role for decades, although the incidence of osteoarthritis in North America is about 50% among people of age 60 and greater.
Cellular Engineering
Authors: Zheng Ming Hao
Published: April 2006

Cellular engineering, principally the control and regulation of cell proliferation, differentiation, and function, is vital to the success of cell‐based therapeutic applications and technologies. Despite significant advances in cell and tissue engineering, current approaches to the engineering of cell‐surface interactions and extracellular matrix design fall short of mimicking the complexity of those relationships in the physiological microenvironment. When considering the bioengineering of complex systems, such as tissue or organs, we must reduce the complexity of the system while remaining in control of cell behavior and function. Therefore, a thorough understanding of the cellular bioprocesses and assembly, and how factors or stimuli affect them, will significantly aid future biomedical engineering research. Optimizing the combinations of cells, matrices, and locally and systemically active stimuli is a complex process characterized by an inter‐reliant set of variables with a potentially infinite scope of combinations.
Cellular and Molecular Imaging
Authors: Landini Luigi , Santarelli Maria Filomena , Positano Vincenzo
Published: April 2006

This chapter surveys some of the electromagnetic and echographic imaging techniques and applications of interest for biology and medicine. First, some fundamental parameters for cellular imaging are introduced as contrast mechanisms, resolution, and penetration depth. Second, the targeting strategies that are now emerging in molecular imaging using modern imaging scanners are reviewed. The last contribution deals with some basic image processing operations such as cells segmentation and counting and integration strategies used in low‐ and high‐resolution imaging techniques.
Clinical Decision Support Systems
Authors: Fotiadis Dimitris , Goletsis Yorgos , Likas Aristidis , Papadopoulos Athanassios
Published: April 2006

Clinical decision support systems (CDSSs) are entities that intend to support clinical personnel in medical decision‐making tasks. In more technical terms, CDSSs are active knowledge systems that use two or more items of patient data to generate case‐specific advice. CDSSs first appeared in the late 1950s but have experienced significant growth over the last three decades providing advice in the clinical decision‐making process. Specific fields of decision support offered by CDSSs include diagnosis, therapy planning, alerting and informing, and information retrieval. CDSSs interact with patient records and measurement devices for data acquisition and knowledge bases for retrieval of knowledge related to the specific case. Combining the data from the above sources, intelligent methods are applied for clinical inference. Rule‐based, probabilistic, and machine learning techniques are employed to provide reliable results to support medical decisions. Recent and forthcoming advances in information technologies are expected to foster CDSSs applied in clinical practice.
Deformable Objects, Interactive Simulation of
Authors: Moustakas Konstantinos , Daras Petros , Tzovaras Dimitrios , Strintzis Michael G.
Published: April 2006

Deformable objects have been extensively used in recent years for simulating the response of various organs of the human body in various stimuli. In addition, applications like virtual surgery and tissue engineering, have emerged, offering to the user, which is usually a student of medicine, a nonhazardous means of training. Simulation based on deformable objects provides the necessary accuracy and realism in this kind of applications, because they model very accurately most human organs. However, the accurate simulation of deformable models at interactive rates is far from being easy, because it involves computationally intensive procedures like the resolution of large systems of equations and the handling of collisions and application specific issues like cutting and suturing. This article presents, after a concise introduction, a comparative study on the fundamental technologies and algorithms used in deformable object modeling and simulation. Finally, it demonstrates indicatively a number of applications so as to illustrate the feasibility and applicability of the simulations.
Defibrillation
Authors: de Jongh Curry Amy , Malkin Robert A.
Published: April 2006

One leading cause of death in the United States is sudden cardiac death, often called cardiac arrest or a massive heart attack. Death results when the normally carefully choreographed electrical impulses of the heart become uncoordinated, a condition called ventricular fibrillation. Reversion of fibrillation to any other, more organized, electrical pattern is called defibrillation. Although electrical defibrillation is now widely practiced, the mechanism by which a strong electrical shock can stop fibrillation is still not understood. Defibrillation may fail because it does not extinguish fibrillation or because it creates a new fibrillation. It is not even clear how an electrical stimulus can affect tissue several centimeters away. Another mystery is why there is such a strong dependence on the temporal pattern, or waveform, of energy delivery for defibrillation. For example, it is more effective to withhold some available energy from certain defibrillators. The most recent data on these unknown aspects of defibrillation are discussed.
Dentin
Authors: Spencer Paulette , Wang Yong , Katz J. Lawrence
Published: April 2006

Dentin is the hydrated composite structure that constitutes the body of each tooth, providing both a protective covering for the pulp and serving as a support for the overlying enamel. Enamel, with its exceptionally high mineral content, is a very brittle tissue. Without the support of the more resilient dentin structure, enamel is so brittle that it would fracture when exposed to the forces of mastication. Dentin supports as well as compensates for the brittle nature of the enamel.

In contrast to enamel, dentin is a vital tissue containing the cell processes of odontoblasts and neurons. As the odontoblasts can be stimulated to deposit more dentin, this tissue is capable of limited repair. The structure‐property relationships of dentin vary with location, physiological, aging, and disease processes. This chapter will review the composition, structure, and properties of the various types of dentin and their effect on current restorative dentistry procedures.
Diabetes Care, Biomedical and Information Technologies for
Authors: Gómez Enrique J. , Elena Hernando M. , Del Pozo Francisco
Published: April 2006

Biomedical engineering research has brought many improvements to diabetes care and management. This article introduces the application of biomedical and information technologies to several aspects of diagnosis, monitoring, and treatment of diabetes. A comprehensive view of technologies is presented that covers biomedical sensors for blood glucose monitoring, instrumentation for self‐monitoring data collection and continuous insulin delivery, information technologies for a patient's monitoring data analysis and visualization, intelligent decision support techniques, and telemedicine systems. Future trends for noninvasive continuous blood glucose monitoring and closed‐loop control systems are also presented to face the challenge to improve the quality of diabetes care and the quality of life of diabetic people.
Distributed Processing
Authors: Miled Zina Ben , Bisen Anand Singh , Li Nianhua , Bukhres Omran
Published: April 2006

Parallel processing describes a computing environment where multiple processors cooperate to solve a given computational problem. It falls under the more general area of high‐performance computing that focuses on accelerating the execution time of applications by using a wide range of hardware and software techniques. Several scientific research areas have used parallel processing to address the computational requirements of data and compute‐intensive applications.

Distributed memory architectures and shared memory architectures are the two main parallel hardware architectures. Distributed computing is often used to refer to the implementation of applications on distributed memory architectures. In the biomedical research field, it is the most widely used form of parallel processing. This article starts by a review of the architectural features of distributed and shared memory multiprocessor systems. The use of these architectures to empower sequence alignment algorithms, phylogenetic trees construction, and protein folding simulations is then discussed. Both general strategies as well as specific case examples of parallel applications in the biomedical research field are presented.
Elasticity
Authors: Fotiadis Dimitrios I. , Protopappas Vasilios C. , Massalas Christos V.
Published: April 2006

The theory of elasticity deals with the systematic study of the stress, strain, and displacement fields in an elastic body under the influence of external forces. In this chapter, we deal with elastic materials (i.e., materials in which the deformation and stress disappear with the removal of the external forces). However, equations for other types of materials are also given. Index notation and Cartesian tensors are presented to enable equations of a continuum to be displayed with remarkable brevity. The concept of stresses and the deformation of a medium are explained. The constitutive or material laws, characterizing the mechanical behavior of the medium, are given. The application of the basic principles of mechanics to the deformable body is described. The elastic properties of biological materials along with examples of selected materials are presented. Also, biomechanical methods for measuring the elastic constants of biological materials as well as applications to diagnosis and treatment are demonstrated. Finally, the problem of free vibrations of an elastic cavity, simulating the human skull, and its solution is given.
Electric Shock
Authors: Morse Michael , Morse Jennifer
Published: April 2006

When human beings were first designed, the designer must have considered that someday they would live in a society in which they were in constant and close proximity to electrical energy. Human skin is a naturally protective barrier to the flow of electricity, but still, under the right conditions, humans can become part of the electric technology and electrical processes that touch every aspect of our daily lives. Commercially generated electricity has been a part of our world for over 100 years. Injury from electrical contact can run the gamut from momentary pain to extensive physical damage that can impair multiple‐organ systems. Primary mechanisms of electrical injury include thermal injury from the electrical energy imparted during the shock, ventricular fibrillation caused when pacing is interrupted by electrical current flow, and electrically induced respiratory arrest. Secondary injury includes soft tissue damage and broken bones resultant from falls and impacts caused by electrically induced muscle contractions. Other secondary injuries caused by electric arcs include flash burns and blunt force trauma. Although electric shock has been studied for well over a century, unexplained responses to electrical contacts still remain, which lead researchers to conclude that, given the complexity and variability of the human machine, human response to electrical energy is far more complex than was originally believed.
Electrochemical Biosensors
Authors: Catherino Henry A.
Published: April 2006

The technology supporting the development of electrochemical biosensors is a high‐interest area for current research programs. Broad interdisciplinary skills are required for the design and construction of these devices. To provide a brief overview of these biosensors, it is helpful to (1) define what is meant by a biosensor and (2) explain the attributes and properties of an effective sensor. The detection approach is electrochemical in origin. This technical discipline constitutes an area of specialization in its own right. The applicable biomaterials and how they produce detection signals brings together biochemical sciences with electrochemical phenomena. Finally, a discussion of the immobilization technologies is presented, which yields a useful biosensor that is a significant materials science development effort. Also, a list of references is presented that can lead the reader to current texts and major review articles addressing the technology in greater detail.