bluuebunny/crossref_metadata_2025 huggingface dataset:
Pulmonary Physiology
Authors: Demenkoff John
Published: April 2006

Present day pulmonary function testing is available in all hospitals and in a less sophisticated form in many physicians’ offices. Such was not the case until the 1940s, when the fruits of physiological research dating back 150 years blossomed on the heels of World War II. This so‐called golden age of pulmonary physiology spurred many of the currently available lung function tests which are used for diagnosis and treatment of existing lung disease; screening for early pulmonary disease; evaluation of respiratory symptoms such as cough and shortness of breath; performance of disability evaluations; preoperative assessment of thoracic and other surgical patients; determination of level of cardiopulmonary fitness; monitoring of adverse pulmonary effect of certain drug therapies.

Over the years, many have contributed to an understanding of the lung and how it works in health as well as in disease. These discoveries have provided building blocks of knowledge, which form the basis of current modern pulmonary function testing. This article reviews the history, principles, and applications of pulmonary function testing.
Radiotherapy Accessories
Authors: Purdy James A.
Published: April 2006

Precise radiation therapy depends on apparatus and devices that help to accurately position the patient’s target volume(s) relative to the treatment machine’s radiation beams on a daily basis. Such devices aid in tumor localization and treatment simulation, patient setup and restraint/repositioning, shaping of field aperture, shaping of the dose distribution, and treatment verification and quality assurance. Precision radiation therapy is necessary as clinical and experimental results show that tumor control and normal tissue response can be a very steep function of radiation dose, and the prescribed curative tumor doses are often, by necessity, close to the doses tolerated by the normal tissues. This article presents a review of the various devices that have been designed to help achieve the high degree of precision and accuracy needed in the planning and delivery of radiation treatments to the cancer patient. Devices used for the both the two‐dimensional approach to planning therapy, i.e., conventional x‐ray simulator, and also the three‐dimensional approach, i.e., virtual simulation using a CT‐simulator, are discussed.
Recorders, Graphic
Authors: Vermarien Herman
Published: April 2006

Graphic recorders are essentially measuring instruments that produce in real‐time graphic representations of (biomedical) signals, in the form of a permanent document intended for visual inspection. Recorded data are thus fixed on a two‐dimensional (2D) medium that can simply be called “paper”. Real‐time paper recordings have the benefit of direct visual access to signal information, allow immediate examination (and re‐examination) of trends (as long strips of paper can be used), present better graphic quality than most screens and can be used as a document for scientific evidence. Two primary aspects describing the performance of the graphic recorder are the properties of the instrument as a recorder of information (measuring accuracy and the ability to display additional information) and the quality of graphics, implying the clearness of the tracings and the overall graphic layout (including identification of the curves by color difference) in relation to ergonomics in visual examination. Secondary aspects are, in general, ease of control of the apparatus, maintenance, costs and service life, and, specifically, input amplification and signal conditioning facilities, waveform monitoring, digital processing, data storage and communication possibilities. In general, recorders use a transducer that converts electrical signal information into a position on the paper. This can be achieved by moving the writing element to the specific position (analog transducers) or by activating the correct point in a large array of stationary, equally spaced writing elements (digital transducers). In most applications the graphic transducer, not the electronic signal conditioning hardware, is the crucial stage in the measuring chain. In the technique of analog transducing, there are essentially two methods: The direct method and the servomethod. Positioning of the writing device can be accomplished by a rotation act (corrected to a translation) or a translation act. The time axis is generated by pulling a strip of paper at constant velocity or in small identical increments. Translational pen servorecorders are used for slow varying signals (bandwidth 0–5 Hz typically), galvanometric pen recorders can handle faster signals (bandwidth 0–100 Hz). Thermal array recorders are digital recorders, which can record higher frequencies in real time with the aid of memory facilities and, evidently, from memory as well with an appropriate paper speed. Nowadays, the borderline between digital graphic recorders, digital oscilloscopes, data‐acquisition systems and PC based virtual measuring instruments becomes less clear. Measurements where immediate visualization of the tracings on a long strip of paper is not required and data are to be digitally analyzed and stored, can be performed by PC with virtual instrument software and printer; Nowadays the majority of data collection is accomplished using digital PC approaches.
Rehabilitation, Orthotics in
Authors: Latta Loren
Published: April 2006

Infectious diseases accounted for 25–33% of the estimated 54 million deaths worldwide in 1988, of which more than half are attributed to tuberculosis, malaria, chronic hepatitis B, diarrheal diseases, and human immunodeficiency virus/Acquired Immune Deficiency Syndrome (HIV/AIDS). Additionally, the first known cases of human influenza caused by the avian influenza virus, N5N1, were identified in Hong Kong in 1997. To address rising national and worldwide public health needs, it is desirable that a sensitive, specific, fast, and simple‐to‐operate device be employed to detect infectious agents. Microbial detection systems that attempt to meet this need have been commercially available from the late 1970s and have progressed significantly with the molecular biotechnology revolution. Contemporary microbial detection systems or biosensors typically consist of a selective biorecognition molecule connected to a transducer that converts a biochemical interaction into a measurable signal. In the near future, biomedical science can realize the integration of all laboratory equipment used in molecular biology on a chip‐based platform arrayed to detect large numbers of pathogens in a high throughput, portable device.
Respiratory Mechanics and Gas Exchange
Authors: Ligas James
Published: April 2006

Knowledge of respiratory mechanics and pulmonary gas transport is essential for understanding both pulmonary function testing and mechanical ventilation. Although sophisticated models of solid and fluid mechanics have been applied to respiration, simple physical principles suffice for clinical use. This article addresses those concepts of respiratory system structure, static and dynamic mechanical behavior, and gas transport essential for those who would either work in a pulmonary function laboratory or deal with mechanical ventilators.

Briefly, the normal lung consists of subunits which are relatively homogeneous both in mechanical properties and in the relative distribution of the ratio of air flow to blood flow. Diseases can result in inhomogeneity, and this affects both tests measuring respiratory mechanics and the expected gas transport. A knowledge of how and why this occurs is essential for anyone concerned with respiration.
Safety Program, Hospital
Authors: Dyro Joseph F.
Published: April 2006

This article describes the broad scope of safety issues in the hospital and recommends ways in which hospitals should address these issues. Particular emphasis is placed on medical devices and instrumentation and how they interrelate with the hospital’s environment, facility, patients and device users and other personnel. Medical device safety depends in large part upon a comprehensive medical device technology management program, which includes elements ranging from technology assessment, evaluation, and procurement to device replacement planning and includes such components as user training, medical device incident investigation, and device quality assurance. The clinical engineer by education, training and experience is shown to be ideally suited to implement and execute a technology management program and to lead in the effort to assure hospital‐wide patient safety. Available resources are described including web‐based training, distance learning, standards, publications, and professional organizations.
Screen‐Film Systems
Authors: Lu Zheng Feng
Published: April 2006

In this article, we discuss the screen‐film system as the image receptor in radiography. We outline the physical and photographic properties of intensifying screens and film. The steps for film processing are delineated. Performance evaluation of the screen‐film system is discussed in relation to image quality and patient radiation dose. Finally, quality assurance and quality control testing are described for the applications of screen‐film systems in radiology.
Sleep Studies, Computer Analysis of
Authors: Shucard David Wm. , Parmenter Brett A. , El Solh Ali A.
Published: April 2006

Until a few years ago, the main problems for computerized sleep systems were the need for efficient data reduction and speed of analysis. The computers were too small and inefficient or too expensive for doing either waveform detection on‐line or storage of the entire raw data. Most of the systems built on the basis of general engineering tools were little used because of the poor correlation with standard visual scoring. The advent of powerful and high computing speed processor has bridged that gap. The availability of digital polysomnography has removed the technical restrictions through increased computing power, storage space, and reduced costs. However, the crude division of the sleep processes into few discrete stages and the difficulties with the translation of spatial information into appropriate algorithms remain the major issues in the development of fully automated sleep systems. The use of predetermined, fixed criteria for methods, waveforms, and states is scientifically erroneous and hazardous. Instead standards should describe the minimum requirements for the recording and analysis of the signals in terms of sampling rate, dynamic range, linearity, and documentation of the methods used.

The purpose of this article is to discuss the use of computers in sleep disorders medicine and how this technology has enhanced the diagnostic and scientific capabilities of the sleep laboratory.
Strain Gages
Authors: Dechow Paul C. , Wang Qian
Published: April 2006

This article reviews strain and stress and their relationship. It also discusses the various types of strain gages in detail.
Thermistors
Authors: Lopes de Melo Pedro
Published: April 2006

Thermistors are transducers constructed of ceramic materials whose electrical conduction properties are temperature sensitive. These devices have been developed to be very sensitive, having excellent long‐term stability, and small size. Thermistors are also relatively inexpensive, presenting a lower cost than either resistance temperature detectors or thermocouples. These characteristics probably situate this device as the most widely used temperature transducer for medical applications nowadays. It makes them ideal for healthcare products that incorporate sensor probes that can be discarded after using and replaced for new ones with the same specification, without recalibration. In this article, thermistor terminology, electrical and thermal properties, linearization, and the basic electronics used in temperature measurements are discussed. Examples of commercial devices dedicated to temperature measurements are also presented. Beyond their utility in temperature measurements, thermistors have found widespread use in a variety of systems for clinical and research applications, such as the measurement of flow, thermal conductivity and diffusivity of biomaterials, and the detection of the presence of liquids. This article includes a brief discussion about these applications, showing the branches of medicine where technology based on thermistor is used, and how this technology can assist each of them.
Tonometry, Arterial
Authors: Eckerle Joseph S.
Published: April 2006

Arterial tonometry is a technique that permits the noninvasive monitoring of the pressure within a superficial artery, such as the radial artery at the wrist. The technique is based on an analysis showing that—under the proper conditions—the artery wall does not influence the transmission of arterial pressure to a sensor applied to the skin. Tonometer sensors have been devised that employ various transduction techniques. Perhaps the most advanced sensors include a multiplicity of independent pressure sensors, and are fabricated from silicon. Tonometric measurements have been used to monitor blood pressure during surgery and similar procedures. They have also been used to determine arterial elasticity and pulse wave velocity. Under favorable conditions, the accuracy of tonometric measurements can be described by standard deviations of ∼ 5 mmHg (0.66 kPa).
Ultrasonic Imaging
Authors: Kripfgans Oliver
Published: April 2006

Ultrasonic imaging is one technique for collecting anatomical and physiological information from within the human body. It can be used for diagnosis (imaging) and for image‐guided therapy, where therapeutic intervention can be applied with direct image‐based feedback. Other modalities include X ray (roentgen radiation), CT (computed tomography), MRI (magnetic resonance imaging), PET or PET/CT (positron emission tomography), and SPECT (single photon emission computed tomography). In contrast to most other imaging techniques, ultrasonic imaging is very attractive to professionals because it is cheap, real time (with >100 full frame images per second, >100 Hz), and it uses nonionizing radiation. Moreover, current clinical ultrasound machines can be integrated into laptop computers with very little external hardware for maximum portability and versatility. These combined features allow the use of ultrasonic imaging in a wide variety of settings, from private physician practices, to ambulances with on‐site paramedics, to battle field situations, where very robust and lightweight equipment is required.
Ultraviolet Radiation in Medicine
Authors: Lloyd J. J.
Published: April 2006

This article gives a review of the uses of ultraviolet radiation (UVR) in medicine. Sunlight has long been associated with health benefits and used for treatment. It is only recently, however, that the beneficial and detrimental effects of UVR on humans has become better understood. Ultraviolet radiation is part of the electromagnetic spectrum between 100 and 400 nm. Acute effects of UVR include erythema (skin redness) and tanning. Delayed effects include skin cancer induction and skin aging. Most human UVR exposure is from the sun, but there is now a wide range of artificial sources available. Fluorescent sources are the most common used in medicine; these and other sources are described. Measurement of UVR is commonly made with physical detectors such as photodiodes that need to be carefully calibrated using more complex equipment such as spectroradiometers. The use of UVR in medical diagnosis (e.g., investigation of skin rashes caused by sunlight) and therapy (particularly in the treatment of skin diseases) is described. A section on sunbeds is included that discusses their medical and cosmetic use and the associated hazards. Other less common uses of UVR in medicine such as photopheresis are mentioned and the article concludes with information on UVR hazard assessment and protection.
Vascular Graft Prosthesis
Authors: Kottke‐Marchant Kandice , Larsen Coby
Published: April 2006

The system of blood vessels in the body is crucial to transport cells, oxygen, and nutrients to the vital organs. When injured by diseases, such as atherosclerosis, the blood vessels may become occluded, leading to decreased blood flow and organ damage, or may be weakened and rupture due to aneurysmal dilatation. One method of treatment is to use surgery to bypass diseased blood vessels by using an artificial blood vessel substitute, or vascular graft prosthesis. Materials currently used in vascular graft prostheses include polyethylene terephthalate (Dacron) and expanded polytetrafluoroethyelene (ePTFE). These devices successfully function as vascular grafts in larger diameter applications, but suitable materials for small diameter prostheses (<5 mm) are still being developed. Current trends in the development of small diameter prostheses include surface modification to prevent thrombosis, incorporation of endothelial cells, and a tissue engineering approach with the development of a biological blood vessel based upon a biodegradable material scaffold.
Ventilatory Monitoring
Authors: Knoper Steven R. , Quan Stuart F.
Published: April 2006

Monitoring of ventilation is an important aspect of the care of all patients with known or suspected cardiopulmonary disease, especially those in an intensive care unit. The intensity of monitoring required is dictated by the clinical need and severity of illness. It can range from simple visual observation to complex invasive technology. There are three broad categories of ventilatory monitoring: (1) assessment of lung mechanical function, (2) measurement of oxygenation, and (3) evaluation of the adequacy of ventilation (CO2gas exchange). Lung mechanical function is usually determined by measurements of airway pressure and lung volume. Arterial blood gas analysis is the primary method to assess oxygenation and ventilation. However, there is widespread use of pulse oximeters to continuously monitor oxygenation. Although technologically feasible, continuous intravascular monitoring ofpaO2,paCO2, and pH has not gained wide acceptance because cost‐effectiveness has not yet been demonstrated. Innovative advances in ventilatory monitoring will need not only to show feasibility, but cost‐effectiveness to be adopted for widespread clinical use.
Visual Field Testing
Authors: Kulkarni Amol D.
Published: April 2006

Evaluation of visual field is an essential investigation in the diagnosis and management of various eye disorders. This article explains the various strategies for visual field testing and their applications in everyday practice. It is aimed at imparting basic concepts in visual field testing and familiarizes the reader with the various aspects of eye disorders causing visual field defects.
X‐Ray Quality Control Program
Authors: Nickoloff Edward L.
Published: April 2006

In order to improve or maintain an optimal achievable level of healthcare, most medical facilities usually have some type of quality assurance program. The quality assurance programs encompass a variety of functions, such as development of comprehensive safety rules, establishment of infection control guidelines, provisions for the efficient management of critically ill patients, establishment of accurate record‐keeping functions, and the development of adequate educational training for the staff (1). In radiology, a portion of the overall quality assurance program is devoted to a quality control program for the X‐ray equipment. Most X‐ray QC programs have several very specific goals toward which they are directed. The list merely enumerates these items. (1) Image quality, (2) patient radiation doses, (3) safety, (4) consistency, (5) economic factors, (6) Regulatory requirements.
X‐Ray Therapy Equipment, Low and Medium Energy
Authors: Ma C‐M Charlie
Published: April 2006

This article describes low and medium‐energy X‐ray equipment for radiation therapy. The history of X‐rays and their applications in radiation therapy is reviewed. X‐ray devices that are used for radiation therapy are discussed in detail based on their energies and applications. Medium energy X‐rays (also called
orthovoltage
X‐rays) are generated by X‐ray devices at an accelerating potential between 150 and 500 kV. Low energy X‐rays (also called
superficial
X‐rays) are generated by X‐ray devices at an accelerating potential between 50 and 150 kV. Very low energy X‐rays that are generated at an accelerating potential <50 kV have mainly been used in
contact
therapy. Methodologies and measurement equipment for calibrating X‐ray units and determining absorbed dose for radiotherapy treatments are described. In‐air and in‐phantom based formalisms and dosimetric data for absolute and relative dose measurement are provided based on the American Association of Physicists in Medicine Task Group 61 recommendations. Practical guidelines are also given for clinical dosimetry including depth dose measurement, output determination, isodose derivation and quality assurance for radiation therapy using low and medial‐energy X‐rays.
Electrophysiology
Authors: Demir Semahat S.
Published: April 2006

This article presents the fundamental principles of cellular electrophysiology and focuses on cellular bioelectricity. First, the concepts of resting membrane potential, action potentials, and the underlying ionic mechanisms are introduced. 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 and dissemination of computational modeels are presented.
Heart, Artificial
Authors: Zapanta Conrad M.
Published: April 2006

Artificial hearts are broadly defined as devices that either supplement or replace the native (natural) heart. These devices can be classified into two groups: ventricular assist devices and total artificial hearts. This article will define the clinical need, review the native heart anatomy and function, describe design considerations for ventricular assist devices and total artificial hearts, review selected designs, and recommend areas for future development.
Hip Joints, Artificial
Authors: Jin Z. M. , Tipper J. L. , Stone M. H. , Ingham E. , Fisher J.
Published: April 2006

A brief introduction to artificial hip joints is followed by a detailed review of both the biotribology of the bearing surfaces and the biological responses to the wear debris for evaluating their performances. Various types of artificial hip joints with different bearing surfaces are considered, including ultrahigh molecular weight polyethylene against metal or ceramic; metal‐on‐metal and ceramic‐on‐ceramic. Future developments of artificial hip joints are discussed.
Impedance Spectroscopy
Authors: Freiesleben De Blasio Birgitte , Wegener Joachim
Published: April 2006

Impedance spectroscopy (IS), also referred to as electrochemical impedance spectroscopy (EIS), is a versatile approach to investigate and characterize dielectric and conducting properties of materials or composite samples. The technique is based on measuring the impedance (i.e., the opposition to current flow) of a system that is being excised with weak alternating current or voltage. The impedance spectrum is obtained by scanning the sample impedance over a broad range of frequencies, typically covering several decades.

This article starts with providing a general introduction to the theoretical background of IS and the methodology connected to impedance measurement. Then, the focus will be on applications of IS, particularly devises for in vitro monitoring of cultured cell systems that have attracted widespread interest due to demand for noninvasive, marker‐free, and cost‐effective methods.
Medical Gas Analyzers
Authors: Drzewiecki Tadeusz M. , Calkins Jerry M.
Published: April 2006

This chapter is devoted to discussing technology and its medical application to gas analysis. Medical gas analysis is becoming an important aspect of patient safety, patient monitoring, diagnosis, and therapy. The application of technology to determine the constituents and quantifying physiologic gases is increasing in importance. For example, being able to identify respiratory gas markers of diseases such as necrotizing enterocolitis and metabolic variables that can assist in the therapeutic management of obesity are becoming recognized and of significant importance. This chapter will review current gas monitoring methods and techniques ranging from colorimetry to solid‐state sensors including state‐of‐the‐art microfluidic devices. Design considerations such as in‐line and out‐of‐line sampling, displays, alarms, calibration, and controls are also discussed.
Microarrays
Authors: Winegarden Neil
Published: April 2006

Microarrays allow for the simultaneous, parallel, interrogation of multiple biological analytes. Originally, microarrays were devised as a method by which gene expression could be measured in a massively parallel manner (all the genes in the genome at once), however, recent advances have demonstrated that microarrays can be used to interrogate epigenetic phenomena, promoter binding, protein expression, and protein binding among other processes. The overall process is reliant upon the manufacture of a highly ordered array of biological molecules, which are typically known entities. The features of this array behave as probes, which react with and bind to the unknown, but complimentary material present in a biological sample. Here we will focus specifically on gene expression (deoxyribonucleic acid, DNA) microarrays, which can be used to assay the activity of thousands of genes at a time.
Microfluidics
Authors: Walker Glenn M.
Published: April 2006

This article provides a brief overview of the fluid phenomena that become prominent at the microscale. Microfluidic devices can be created that take advantage of these phenomena to provide novel functionality. The modeling of microfluidic systems, from the microscopic to the macroscopic level is presented. Pumping methods using pressure and electric fields are discussed. Methods of fabricating microfluidic devices are examined. Finally, examples of biomedical devices that use microfluidics are given.
Microscopy, Confocal
Authors: Claxton Nathan S. , Fellers Thomas J. , Davidson Michael W.
Published: April 2006

Laser scanning confocal microscopy has become an invaluable tool for a wide range of investigations in the biological and medical sciences for imaging thin optical sections in living and fixed specimens ranging in thickness up to 100 μm. Modern instruments are equipped with three–five laser systems controlled by high speed acoustooptic tunable filters (AOTFs), which allow very precise regulation of wavelength and excitation intensity. Coupled with photomultipliers that have high quantum efficiency in the nearultraviolet, visible, and near infrared spectral regions, these microscopes are capable of examining fluorescence emission ranging from 400 to 750 nm. Instruments equipped with spectral imaging detection systems further refine the technique by enabling the examination and resolution of fluorophores with overlapping spectra, as well as providing the ability to compensate for autofluorescence. Recent advances in fluorophore design have led to improved synthetic and naturally occurring molecular probes, including fluorescent proteins and quantum dots, which exhibit a high level of photostability and target specificity.
Microscopy, Electron
Authors: Dadsetan Mahrokh , Lu Lichun , Yaszemski Michael J.
Published: April 2006

Electron microscope development occurred as needs for better image magnification and resolution exceeded the capabilities of light microscopy. A light microscope, even with optimal lenses and illumination, cannot distinguish objects that are < 0.2 μ. Electron microscopy as an imaging technique allows direct observation of biological objects, whereas other available techniques are indirect and in some instances nonspecific. Electron microscopy enables resolution of the relationship among objects to occur at the molecular level. Electron microscopy provides the ability to understand structure–function relationships at this level. Compared with other laboratory diagnostic methods, electron microscopy excels with respect to speed and image quality. These characteristics permit detection and identification of both anticipated pathologic agents and those not initially considered by the clinician. Ultrastructural study may be applied to a variety of substances including biological materials. By examination of specially prepared tissue sections, changes not perceived by light microscopy can be identified, leading to improved diagnostic interpretations.
Microscopy, Fluorescence
Authors: Pelet Serge , Previte Michael , So Peter T. C.
Published: April 2006

Fluorescence microscopes quantify the structure and biochemistry in specimens with submicron spatial resolution based on fluorescence contrast. This article covers the spectroscopic principles underlying fluorescence imaging. The design considerations for several basic forms of fluorescence microscopes will be presented. Fluorescent probes are classified and their optical properties will be discussed in the context of their uses in microscopic imaging. Finally, advanced modalities for functional imaging and their biomedical applications are described.
Microscopy and Spectroscopy, Near‐Field
Authors: Micic Miodrag
Published: April 2006

This article reviews the principles and applications of optical imaging beyond the diffraction limit using near‐field optics. Such a technique allows optical imaging and spectroscopy with lateral resolution up to 20 nm, and is promising to revolutionize research in life science disciplines, with a possible plethora of practical biomedical applications, especially in the field of
in vitro
diagnostics. The article provides an introduction to the near‐field optics as applied in microscopy, and the fundamental concepts behind the two basic types of near‐field scanning optical microscopes: aperture‐based and apertureless, along with examples of life science and biomedical applications.
Nanoparticles
Authors: Salata O. V.
Published: April 2006

This article explores the meaning of the word “nanoparticle,” defines various classes of nanoparticles, describes their possible manufacturing routes, and discusses their uses in biological and medical fields. Potential health risks associated with nanoparticles are discussed.
Picture Archiving and Communication Systems
Authors: Andriole Katherine P.
Published: April 2006

This article discusses the history of picture archiving and communication systems and reviews the key components and current trends.
Polymerase Chain Reaction
Authors: Metzker Michael L. , Caskey Thomas C.
Published: April 2006

Polymerase chain reaction a rapid
In vitro
DNA synthesis process, which can amplify up to a billion copies of a given nucleic acid target. It has been extensively applied for the identification, detection and diagnosis of genetic and infectious disease.
Prostate Seed Implants
Authors: Zaider Marco , Silvern David A.
Published: April 2006

An increasing number of men undergo brachytherapy (low‐ or high‐dose rate) for the treatment of localized prostate cancer. In the past decade, permanent seed implant has witnessed significant progress in implantation techniques, dosimetry, seed localization, image‐guided treatment planning, and post‐treatment evaluation. This article, written for those who wish to keep abreast of progress in this field, presents a pedestrain‐level discussion of these advances and is meant to acquaint the reader with the basic physics of seed implants while offering practical guidelines for their clinical use.
Radiation Dosimetry, Three‐Dimensional
Authors: Ibbott Geoffrey S.
Published: April 2006

Accurate delivery of radiation therapy is essential for the treatment to have the greatest probability of success. Determining the dose delivered by radiation beams and radioactive sources requires complex dosimetry procedures and sophisticated computerized treatment planning software. Validating the software to assure its accuracy is an essential component of the quality assurance program in a radiation therapy department.

In recent years, radiation therapy has evolved to take advantage of new treatment delivery capabilities and ever‐more complex treatment planning techniques. These techniques allow the dose distribution to be tailored to closely match the shape of the target volume and avoid nearby sensitive tissues. Consequently, dosimetric validation devices must also allow the accurate measurement of dose in three dimensions.

Conventional dosimetry systems measure the dose at a point or in a plane, and mapping a 3D dose distribution is difficult at best. As a result, there is a need for a reliable 3D radiation dosimetry system, with the capability of integrating the dose from a complex, and possibly dynamic treatment, so that the delivered dose can be mapped and compared with computer simulations. Today, the only true 3D dosimeters are radiosensitive gels and plastics that can be constructed to fill volumes and conform to complex surfaces. The science behind these dosimeters is developing rapidly, and their routine use in the clinic is believed to be imminent.
Radiology Information Systems
Authors: Honeyman‐Buck Janice C.
Published: April 2006

Radiology information systems (RIS) are evolving from being stand‐along radiology order entry, study management, film tracking, charge capture, and billing systems to being an integral part of a series of highly integrated systems that essentially manage and report patient healthcare information. There is a national initiative to provide every person with the ability to request or access their health history, whenever and wherever needed, while maintaining the privacy and security of the records. To that end, the Electronic medical record (EMR) is being adopted by more healthcare institutions. The use of established standards will be crucial for assuring that these EMRs will be able to interface and that a person’s information will be not only accessible, but usable at another location. It is expected that the RIS of the future will expedite the exchange of information of all radiology data with the EMR and will support new devices for viewing and disseminating images and reports.
Radiosurgery, Stereotactic
Authors: Wagner Thomas H. , Meeks Sanford L. , Bova Frank J.
Published: April 2006

The idea of using radiation as a neurosurgical tool was conceived in the 1950s, and became reality in the 1960s. In the decades since, technological advances in computing power and medical imaging have combined to allow very precise and conformal radiation treatments for intracranial and extracranial anatomical sites on a routine basis in many medical centers. This article provides a brief overview of major concepts in stereotactic radiosurgery, and also surveys major recent developments and advances in the field.
Radiotherapy, Intraoperative
Authors: Biggs Peter J.
Published: April 2006

Intraoperative radiotherapy (IORT) is a technique involving surgery and radiation therapy whereby a patient undergoes surgery for partial or complete removal of a tumor or for exposure of the malignant tissue or organ and, before closing the incision, the site of the tumor is irradiated with either X‐rays or electrons. The rationale for this treatment modality is that the dose that can be safely delivered to a tumor in the body by external radiation is limited by normal tissue tolerance of intervening tissues. By removing normal tissue and organs from the field, the area of disease can be treated to a higher dose with the intent of increasing the local control of the disease. The technique of IORT has been applied to many sites in the body including rectum, pancreas, retroperitoneal sarcoma, bladder, breast, and head and neck. Intraoperative radiotherapy is a specialized technique that requires a well‐trained team of surgeons, oncologists, medical physicists, therapists and nurses, as well as specialized equipment for a successful program.

IORT has been performed sporadically since the earliest days of radiotherapy, when kilovoltage X‐rays were the only radiation modality available, but it was not until the 1960s and the advent of linear accelerators with electron beams that IORT became a widely used modality. Interest continued to be strong until the 1990s, but then began to wane slightly due to the high cost of equipment, the time and number of staff to perform the treatments, and reimbursement issues. However, since the late 1990s, mobile linear accelerators have become available and this has increased interest in IORT, particularly in the field of breast cancer treatment. Currently, ∼ 26 of these mobile units have been installed in the United States and Europe by three manufacturers. Alternative techniques using photons have also found increasing use in IORT, particularly brachytherapy techniques using192Ir radioactive sources and, to a lesser extent, low energy photons.

This article will review the history of IORT, the equipment that is needed for the procedure, the dosimetry and radiation safety aspects, clinical results, and future directions.
Spinal Implants
Authors: Marcolongo Michele , Joshi Abhijeet
Published: April 2006

Spinal implants constitute the fastest growing segment of the orthopaedic medical device industry. The area has until the last five to ten years been vastly under‐studied for the proportion of patients who are afflicted with diseases and injuries to the spine. Consequently, new spine medical devices and medical device companies are emerging every day with new and better treatment strategies for prevalent spine disorders. This chapter will explore the physiological conditions and disease states that require treatment and then demonstrate some treatment strategies that are being used today. The devices in this text are not comprehensive but do allow an understanding of the state‐of‐the art in medical treatment of spinal disorders.
Human Spine, Biomechanics of
Authors: Goel Vijay K. , Biyani Ashok , Ferrara Lisa , Rengachary Setti S. , McGowan Dennis
Published: April 2006

The basic anatomy of the human spine is described to highlight the interaction among spinal components that provides the desired function in a normal person. The factors that lead to instability–abnormal motion are described. Abnormal motion may be due to external environmental factors to which the spine is subjected to during activities of daily living (e.g., impact, repetitive loading, lifting) degeneration, infectious diseases, injury or trauma, disorders, and/or surgery. The biomechanics encompasses the mechanical aspects of conservative treatments, surgical procedures and spinal stabilization techniques. These issues are narrated in this article. However, the field of spinal biomechanics is very broad and it is not practical to cover all aspects in one article. For example, this article does not deal with whiplash mechanisms, impact loads, injury biomechnaics due to falls, and in sports to name a few.
Sleep Laboratory
Authors: Bogan Richard K. , Youngstedt Shawn D.
Published: April 2006

The sleep laboratory consists of diagnostic bedrooms, accompanied by a central technical area for collection of data, observation of patients and data processing. The standard polysomnographical (PSG) recording includes placement of electroencephalographic (EEG) electrodes at specific scalp sites; electroculographic (EOG) electrodes aroundthe eyes (for detection of rapid eye movement sleep); electromyographic (EMG) electrodes on the chin; measurement of respiration and airflow for detection of sleep disordered breathing; and leg EMG electrodes for detection of limb movements during sleep. Scoring is typically conducted in 30 s epochs, in which accepted criteria are used to define the epoch awake or the specific stage of sleep, arousals, respiratory events, and so on. Specific criteria are also used to diagnose various sleep disorders and treatment response. Recent trends have involved more emphasis on digitial versus analog data collection, allowing for better automation and collation of the data. Potentially, this trend will also allow for more reliable and detailed assessment of sleep.
Teleradiology
Authors: Huang H.K.
Published: April 2006

Teleradiology is neither a single medical device nor an instrument, instead, it is a system integration of various imaging devices using communication technology and system software connecting multiple imaging centers and expert centers together. Teleradiology is closely related to PACS (Picture Archiving and Communication System) in terms of technologies used as well as operation. Teleradiology components include image capture, data formatting, image storage, display workstation, communication networks, user friendliness software, image compression, and image security. Teleradiology have several operation models, from the simplest off‐hour reading, application service provider (ASP), Web‐based, to more complex models like PACS and teleradiology combined and enterprise level using grid computing technology. Several important issues to be considered in teleradiology are the trade off between teleradiology technologies and operation, image data security, and medical–legal concern.
CO2Electrodes
Authors: Severinghaus John W.
Published: April 2006

The CO2electrode is a membrane covered glass pH electrode with an internal electrolyte film containing NaCl and NaHCO3. The electrical output is a log function ofpCO2(partial pressure) exposed to the sensor face. At 37°C, output is 60 mV for a 10‐fold change inpCO2. The CO2electrode was invented by Richard Stow, Ph.D. at Ohio State University Hospital in 1954 to help with management of paralyzed polio victims who were being artificially ventilated. His original device failed because his internal electrolyte was distilled water. Severinghaus added bicarbonate and salt to stabilize it. Manufacture of the device began in 1959.

Transcutaneous (tc) CO2electrodes were introduced in the mid‐1970s when transcutaneous O2electrodes were found to adequately reflect arterial blood oxygen pressure (paO2), especially in premature infants whose immature lungs required extra oxygen, but where too much oxygen caused blindness. The tcpCO2electrodes are combined with tcpO2electrodes in a single small sensor that is attached with adhesive to skin surfaces. These devices are internally heated to increase local skin blood flow. At 43–45°C, skin surfacepO2resembles (arterial)paO2, but skin surface tcpCO2is ∼ 1.4 times higher thanpaCO2. The instrument is calibrated to correct this difference.

Transcutaneous oxygen and carbon dioxide electrodes have found many uses in addition to their use for newborn infants. However, their usefulness fell after pulse oximetry became common in 1985. The electrodes need careful maintenance with membrane changes and limitation of time on a skin location, to avoid burns.
Cellular Imaging
Authors: Periasamy Ammasi
Published: April 2006

Microscopy becomes an essential tool for cellular imaging. The development of new fluorescent markers, such as green fluorescent proteins, generated great interest to measure cellular signals qualitatively and quantitatively using advanced fluorescence microscope techniques including wide‐field, confocal, multiphoton, lifetime, Förster resonance energy‐transfer (FRET), and correlation spectroscopy. The application dictates the selection of microscope methodology to investigate the cellular dynamics. In this article, we explore selected applications such as localization of protein molecules using FRET microscopy and drug cellular uptake using multiphoton and lifetime imaging microscopy. Nonfluorescent techniques, such as Raman and coherent antistokes Raman spectroscopy (CARS), are also described for lipid imaging.
Continuous Positive Airway Pressure
Authors: Rapoport David M. , Leder Ron S.
Published: April 2006

This article reviews CPAP in OSAHS, monitoring and titration issues, indications for use of CPAP in OSAHS, and issues in comfort for OSAHS.
Boron Neutron Capture Therapy
Authors: Barth Rolf F. , Coderre Jeffrey A. , Vicente M. G. H. , Blue Thomas E
Published: April 2006

Boron neutron capture therapy (BNCT) is based on the nuclear reaction that occurs when boron‐10, is irradiated with low energy‐thermal neutrons to yield high linear energy transfer alpha particles and recoiling lithium‐7 nuclei. Clinical interest in BNCT has focused primarily on the treatment of high grade gliomas, and either cutaneous primaries or cerebral metastases of melanoma, and more recently head and neck and liver cancer. Neutron sources for BNCT currently are limited to nuclear reactors and these are available in the United States, Japan, several European countries, and Argentina. Accelerators also can be used to produce epithermal neutrons and these are being developed in a number of countries, but none are currently being used for BNCT.

Two boron drugs have been used clinically, sodium borocaptate or “BSH” (Na2B12H11SH), and a dihydroxyboryl derivative of phenylalanine, referred to as boronophenylalanine or “BPA”. The major challenge in the development of boron delivery agents has been the requirement for selective tumor‐targeting in order to achieve boron concentrations (∼ 20 μg·g−1tumor) sufficient to deliver therapeutic doses of radiation to the tumor with minimal normal tissue toxicity. Over the past 20 years, other classes of boron‐containing compounds have been designed and synthesized that include boron‐containing amino acids, biochemical precursors of nucleic acids, DNA binding molecules, and porphyrins derivatives. High molecular weight delivery agents include MoAbs and their fragments, which can recognize a tumor‐associated epitope, (e.g., EGF) and liposomes. However, it is unlikely that any single agent will target all or even most of the tumor cells, and most likelycombinationsof agents will be required and their delivery will have to be optimized.

Current or recently completed clinical trials have been carried out in Japan, Europe, and the United States. The vast majority of patients have had high grade gliomas. Treatment has consisted first of “debulking” surgery to remove as much of the tumor as possible followed by BNCT at varying times after surgery. Both BSH and BPA have been used as the boron delivery agents, administered intravenously. The best survival data from these studies are at least comparable to those obtained by current standard therapy for glioblastomas (GBM), and the safety of the procedure has been established.

Critical issues that must be addressed include the need for more selective and effective boron delivery agents, the development of methods to provide semiquantitative estimates of tumor boron contentpriorto treatment, improvements in clinical implementation of BNCT, and finally, a need for randomized clinical trials with an unequivocal demonstration of therapeutic efficacy. If these issues are adequately addressed, then BNCT could move forward as a treatment modality.
Adhesion of Bacteria
Authors: Mitik-Dineva Natasa , Stoddart Paul R. , Crawford Russell , Ivanova Elena P.
Published: April 2006

The adhesion of bacteria to biological and nonbiological surfaces is of fundamental importance in regulating their interactions with the environment. A range of different strategies that are employed by bacteria for attachment are reviewed. This article describes the general principles that apply to mechanisms of adhesion, the current status of knowledge in understanding the drivers of bacterial adhesion, and the impact of surface characteristics on bacterial metabolic activity and biofilm formation.