bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radiation Therapy, Quality Assurance in
Authors: Gejerman Glen , Hanley Joseph 
Published: April 2006

Abstract
A prerequiste to a successful radiation oncology prgram is accurate treatment planning and consistent treatment delivery. The Nuclear Regulatory Commission and most state regulatory bodies have published quality assurance guidelines requiring interval testing of the simulation, treatment planning, and treatment delivery process. Recognizing the challenge of ensuring proper maintenance and use of increasingly complicated systems, the American Assiciation of Physicists (AAPM) published a series of comprehensive quality assurance guidelines that can be applied to X‐ray and CT simulators, treatment planning systems, and linear accelerators. Comprehensive quality assurance must encompass both systematic and random uncertainity in treatment planning and delivery to minimize their occurrence. The many factors that contribute to target dilineation uncertanity including acquisition parameters, organ motion, imaging modality, image fusion, and intra‐observer variablity should all be examined closely for their contributions to treatment uncertainities. To minimize treatment inaccuracies, it is essential that each radiation oncology department establishes a “quality system” or quality assurance program to provide the organizational structure, responsibilities, procedures, processes, and resources for assuring the quality of patient management.
Radiation Therapy Treatment Planning, Monte Carlo Calculations in
Authors: Chui Chen‐Shou , Yorke Ellen , Sheu Ren‐Dih 
Published: April 2006

AbstractThe distribution of radiation in three‐dimensional (3D) heterogeneous geometry is governed by the Boltzmann transport equation. In general, it does not have analytic solutions, and therefore one has to rely on numerical methods.Monte Carlo simulation is probably the most accurate numerical method for such problems. It uses random sampling techniques to simulate various physical events. In radiation therapy, the most commonly used radiations are photons and electrons with energies up to 20 MeV. The geometry can be the machine that produces the radiation or the 3D images of the patient under treatment. In a Monte Carlo calculation for radiation therapy treatment planning, radiation particles are generated and tracked through various components in the machine head and followed into the patient body, inside of which the relevant physical events are simulated and energy deposited.Several examples are given to illustrate the application of Monte Carlo calculations in radiation therapy treatment planning. These include the calculation of beam characteristics by simulating the machine head, and dose calculations in patient for photon and electron beams.
Radiation Therapy, Intensity Modulated
Authors: Grant Walter 
Published: April 2006

AbstractIn 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

AbstractComputer‐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

Abstract
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

AbstractSkin 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

AbstractStatistics 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

AbstractTactile 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

Abstract
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

Abstract

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

AbstractA 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

Abstract
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

Abstract
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

AbstractMicrodialysis 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

Abstract
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

Abstract
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

Abstract
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

AbstractThis 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

AbstractProteins 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.