Electromagnetic Radiation and Human Health

EMF Protection

This ebook is the complete guide to learning about electrical sensitivity and how to prevent getting it in your life. You will learn what electrical sensitivity is, and what causes it. Once you have started learning about it you will learn how to get rid of it and protect yourself from the dangers of electrical sensitivity. You will also learn how to heal yourself. This book is the product of careful research by the scientific and medical communities into the dangers and preventative measures of electrical sensitivity. ES is one of the most under-diagnosed conditions in the world right now, and this ebook is designed to education people as to how it works and how to prevent it. Do not let it take hold of your family; take control and prevent it now! Do not let yourself get any more hurt; learn about this condition and fight it!

How To Beat Electrical Sensitivity Summary

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Radiofrequency Electromagnetic Fields

Time-varying electromagnetic fields with frequencies above 10 MHz (RF fields), that are used in MR studies to excite and prepare the spin system, deposit energy in the human body that is mainly converted to heat. The parameter relevant for the evaluation of biological effects of RF fields is the increase in tissue temperature, which is dependent not only on localized power absorption and the duration of RF exposure, but also on heat transfer and the activation of thermoregulatory mechanisms leading to thermal equalization within the body.

Radiation exposure in children

The biological effects of ionizing radiation exposure from devices are important. It is generally accepted that there is no minimal threshold that can be said to be harmful. In practice, it is recommended that radiation levels be kept down to the lowest practicable level. One cannot say there is a safe dose. Children are considerably more sensitive to radiation than adults. With a longer life expectancy, children have a larger window of opportunity for radiation effects, namely carcinogenic risk 66 . One needs to assess lifetime risk and understand the genetic and carcinogenetic effects on children 67 . Of recent concern is the increasing use of pediatric computed tomography (CT), an invaluable tool for imaging children, especially those who are younger, sick, and less cooperative. CT has been useful in the evaluation of head trauma patients and delineating abnormal lesions, especially soft tissues areas. However, with increasing numbers of CT imaging being performed, the quantitative...

Radiation Exposure Of Staff

Various hospital staff members are exposed to radiation during the sentinel node procedure. Because the surgeon is in closest contact with both tumor and sentinel node, dose calculations will be focused primarily on this person. Radiation exposure of others (e.g., nurses and pathology personnel) can be deduced from the values that apply to the surgeon. The skin of the surgeon's hands is expected to receive the highest dose and therefore serves as the dose-limiting organ. The radiation exposure of the surgeon during the operation is determined by the amount of tracer that is retained around the tumor, the distance from the injection depot to the surgeon's hands, and the duration of exposure. The amount of tracer uptake in the sentinel node is small and will not exceed a few percent of the total injected dose 18,19 .

Electromagnetic interference with medical devices

Medical device EMI is the disruption of the normal function of electrically powered medical devices by conducted or radiated electromagnetic energy or by electrostatic discharge (ESD). EMI can affect the safety or effectiveness of active, electrically powered medical devices in ways that can pose significant risks to patients and medical device users, and it has been reported to result in patient injury and death 1,2 . These events may occur in the hospital, the home, the workplace, the shopping mall, the airport, or other public places. Reports of EMI-related medical device problems are scrutinized by medical device manufacturers and regulators. Many manufacturers point to the paucity of confirmed reports and question the extent of the problem. Regulators and those involved in writing standards for electromagnetic compatibility (EMC) believe that EMI problems are underreported 3 , that the reported cases are indicative of more widespread issues, and strive to prevent future EMI...

Radiation Exposure

CT utilizes X-rays to obtain diagnostic information. While the radiation exposure should be limited as much as possible, a certain quantum of X-rays is required to achieve an acceptable image quality. The X-rays emitted by the CT scanner interact with the body tissue by depositing energy, called dose. Rather than the ion dose (unit Roentgen, R), the absorbed dose (unit Gray, Gy) is most frequently considered. Overall, the best way of reducing radiation exposure is to avoid unnecessary examinations and to use the correct settings to minimize dose.

The Kinetics of Pathogen Killing

Sigmoid and asymptotic killing curves are exceptions to the rule of exponential killing rates. The steepness of the killing curves depends on the sensitivity of the microorganisms to the agent as well as on the latter's effectiveness. The survivor exposure curve drops at a steeper angle when heat is applied, and at a flatter angle with ionizing radiation or chemical disinfectants. Another contributing factor is the number of microorganisms contaminating a product (i.e., its bioburden) when applied to higher organism concentrations, an antimicrobial agent will require a longer exposure time to achieve the same killing effect.

Genetic Basis for NBS

DNA damage triggers specific cellular responses that ensure the maintenance of genomic integrity. The induction of DNA strand breakage by ionizing radiation (IR) results in activation of signaling pathways that lead either to elimination of damaged cells by programmed cell death or arrest of cell-cycle progression and repair of the DNA breaks (Elledge 1996 Zhou and Elledge 2000). Among the various proteins that contribute to DNA damage response, (ATM (serine-threonine kinase) protein plays a prominent role. Cells from individuals with ataxia telangiectasia exhibit defects in cell-cycle checkpoints operative in Gi, S, and G2 phases, as well as radiation hypersensitivity and an increased frequency of chromosome breakage (Kastan and Lim 2000 Kastan et al. 2000). Activated ATM, in turn, triggers the activation of cell-cycle checkpoints and DNA repair through the phosphorylation of various proteins, including nibrin (Petrini 1999 Lim et al. 2000 Wu et al. 2000 D'Amours and Jackson 2002)....

Development of Guidance on Protection

The ICNIRP Guidelines (1998) have been adopted by more than 40 countries worldwide. The European Union, for example, has adopted a Directive on the minimum health and safety requirement regarding the exposure of workers to the risks arising from physical agents (electromagnetic fields), which is based largely on the ICNIRP Guidelines (EU, 2004).

Side Effects And Radiation Dose

Radiation exposure is another consideration. Use of a radiopharmaceutical inevitably results in exposure of the patient and the hospital personnel to some radiation. Acceptable limits of such exposure are set by government bodies and vary from one region to another. The radiation dose is low for all tracers because of the favorable characteristics of 99mTc (no beta emission) and the small dose that is needed. However, the exposure is difficult to calculate precisely, because of the variability of the injection site. This subject is discussed in detail in Chapter 13.

Electronic Absorption Spectroscopy

Electronic absorption is often used for a quantitative analysis of a sample (Tinoco et al., 1978). The basic absorption process uses a linear absorption of light from a conventional lamp (e.g., a Xe lamp), which provides a continuous distribution of the electromagnetic radiation from UV to near IR. The spectrometer used for this purpose is often called a UV-visible spectrometer, and it measures linear electronic absorption. This linear absorption is defined by the Beer-Lambert's law, according to which the attenuation of an incident beam of intensity Io at frequency v is described by an exponential decay whereby the output intensity I is given as

Contraindications Pregnant Patients

Pregnant patients undergoing MR examinations are exposed to the combined magnetic and electromagnetic fields used in MR imaging. The few studies on pregnancy outcome in humans following MR examinations have not revealed any adverse effects, but are very limited because of the small numbers of patients involved and difficulties in the interpretation of the results. It is thus advised that

Anthropometric Assessment Of Body Fat Distribution

Body circumferences and their ratios are used to indicate the distribution of body fat. The most important variations, in terms of health associations, are between the amounts of fat in internal, mainly intra-abdominal sites, as distinct from subcutaneous sites (Figure 4.8). The 'gold standard' for measuring fat depots in these sites is scanning by MRI (Figure 4.2). CT gives almost equal information but the small radiation exposure limits its acceptability.

The Many Types of Magnetic Resonance Examination

MR techniques do not rely on ionizing radiation and are not associated with exposure to any radioactivity at all. As expected, the former state of alignment is preferred and the majority of nuclei in a large 'ensemble' or collection of nuclei will assume this state (low energy). However, a certain proportion of the nuclei will be anti-aligned (high energy) and it is this population difference that underlies the phenomenon of NMR. In the presence of a pulse of electromagnetic waves whose energy corresponds to the difference between these two states, the energy from these waves will be absorbed by the system - a process of resonance (hence nuclear magnetic 'resonance') - and the populations of spins in the two states will be equalized. The frequency region of the electromagnetic spectrum (in the order of tens of megahertz) that is suitable for this purpose is known as radiofrequency (RF). This perturbed state is temporary and, once the application of the electromagnetic...

Intervention by Physical Means Radiation Hyperthermia Electrochemical Therapy

Ionizing radiation therapy (RT) is an important local modality for the treatment of cancer. RT is largely based on the ability to kill cancer cells by direct cytotoxic effects. A large body of evidence is accumulating on the ability of RT to modify the tumor microenvironment and generate inflammation. This might have far reaching consequences regarding the response of a patient to treatment, especially if radiation induced tumor cell kill were to translate into the generation of

Quantitative Binding Affinity Measurement

The development of improved methods to accurately determine the absolute binding affinities of drug-like small molecules to their receptors is an active and fruitful area of research. Most methods for absolute affinity quantitation (as compared to relative affinity measurements based on displacement of a known inhibitor) rely on titration of a receptor by a ligand and readout of a signal corresponding to formation of the receptor-ligand complex. In the case of spectroscopic methods, the readout is based on emission or absorption of electromagnetic radiation for thermophysical methods such as isothermal calorimetry, the readout is based on emission of heat. In ALIS, the protein-ligand complex concentration is determined from the MS signal measured for the ligand after its dissociation from the complex. This section describes a straightforward ALIS-based titration method to quantify the binding affinities between unlabelled small molecules and their native protein targets.

Optical Fiber Delivery System

Depending on the size (core diameter) and the refractive index of the core and the cladding media, an individual optical fiber can support different types of mode propagation which define the electric field distribution of the electromagnetic radiation within the fiber. Typically, fibers of diameter 2-4 mm can support a single mode of propagation and are called single-mode fibers. Larger-diameter fibers are multimode fibers that are capable of propagating many modes simultaneously. Single-mode fibers are desirable for many applications, such as nonlinear optical excitation, which require a well-defined mode. There are fibers that preserve the polarization of the coupled polarized light. They are called polarization preserving fibers.

Light behaves as both a particle and a wave

Thylakoid Stroma

Light is a form of electromagnetic radiation. It comes in discrete packets called photons. Light also behaves as if it were propagated in waves. The amount of energy contained in a single photon is inversely proportional to its wavelength the shorter the wavelength, the greater the energy of the photons. For example, a photon of red light of wavelength 660 nm has less energy than a photon of blue light at 430 nm.

Acute Myeloid Leukemia

Myelodysplastic syndromes and myeloproliferative syndromes (Chapter 13) Exposure to ionizing radiation treatment with chemotherapy agents. The following are chemotherapy agents associated with secondary AML Nitrogen mustard Cyclophosphamide Ifosfamide Chlorambucil Melphalan Etoposide.

Case 12 A Shock at Washing

Description of the atrial and ventricular electrogram the atrial and ventricular electrograms show large as well as sinusoidal deflections. The large deflections represent the baseline rhythm, cycle length 850 ms. The sinusoidal deflections demonstrate high-frequency noise due to electromagnetic interference. Diagnosis external electromagnetic interference. Action instructions for the patient to avoid sources of electromagnetic interference. Grounding of the washing machine.

Operational Measures of Exposure

A nearly ubiquitous challenge in collecting accurate data on exposure is the difficulty of gathering information over the potential etiologic period of interest. That is, the ideal definition often includes a time dimension over which exposure needs to be integrated or monitored. Even our most elegant tools, whether based on self-report, environmental measurements, or biological markers, rarely capture the exposure of interest over the period of interest. If we are interested in several years or decades of dietary intake of a specific nutrient, our options for data collection are limited. We can ask for people to use their memories to integrate over the interval, we can obtain more precise measurements at a point or several points over the interval, or some combination, such as a precise measure at one point and self-report regarding stability over a longer interval. In many instances, the most sophisticated, detailed, and accurate exposure indicators are only applicable to a brief...

Nilsa Loyo Berrios Michele G Bonhomme Donald M Witters Nancy A Pressly and Jeffrey L Silberberg

Surveillance of adverse medical device events (AMDEs) is an essential component of assuring the postmarket safety of medical devices. Timely identification and assessment of problems allows the Food and Drug Administration (FDA), manufacturers, and healthcare providers to take remedial actions that prevent future problems and decrease the severity of events should adverse events occur. The written reports of adverse events involving FDA-approved medical devices, which FDA receives through the Medical Device Reporting (MDR) system and the agency's MedWatch program, are a key source of AMDE surveillance data. These reports are entered into the Manufacturer and User Facility Device Experience database (MAUDE). We explored different methodologies for analyzing surveillance reports on electromagnetic interference (EMI) with medical devices. Two FDA studies of EMI adverse event reports that were submitted through the MDR system, conducted at different times and using different...

Longterm Management Of The Patient Following Pituitary Radiotherapy

Pituitary irradiation is used to decrease the rates of tumor recurrence and to reduce the excess hormone secretion of functioning pituitary adenomas. There is some debate regarding the case selection of patients best treated by this modality. Conventional irradiation of the pituitary fossa is three-field external beam irradiation. This stereotactic technique delivers charged particle beams that can be targeted to deposit ionizing radiation at a specific depth. Radiotherapy of this type is delivered in fractions (usually less than 200 cGy d) designed to reduce damage to the optic chiasm, that is believed to be largely mediated through effects on the blood vessels supplying this structure.

Examine Multiple Indicators of Exposure

Odds Ratios and 95 Confidence Intervals for Magnetic Field Exposure and Acute Lymphocytic Leukemia from Different Residences, Categorised According to Initial Cutoff Points of Magnetic Field Exposure, National Cancer Institute Childhood Leukemia Study Table 8.2. Odds Ratios and 95 Confidence Intervals for Magnetic Field Exposure and Acute Lymphocytic Leukemia from Different Residences, Categorised According to Initial Cutoff Points of Magnetic Field Exposure, National Cancer Institute Childhood Leukemia Study

Statistical procedures

Electromagnetic interference (EMI) 1194 Electromagnetic interference (EMI), compatibility incompatibility 2345 Descriptive statistics are presented for the suspected EMI cases on report source, patient's age and gender, event location and type of event. EMI-affected devices were classified following the definition for device type (implanted, monitoring, therapeutic, surgical, diagnostic, and prosthetic) from the Code of Federal Regulations (CFR) 21 . Medical EMD sources were also classified by device type and non-medical sources were classified as products related to 'Conducted Electromagnetic Energy (Alternating Current)' or 'Radiated Electromagnetic Energy' (wireless technology).

Evanescent Wave Biosensors

Evanescent wave sensors utilize the interaction with the electromagnetic field (evanescent wave) that extends away from the surface of the light guiding medium, whether a planar waveguide, a channel waveguide, or a fiber (Rowe-Taitt and Ligler, 2002 Boisde and Harmer, 1996). In other words, these sensors rely on the light that is not confined within the waveguide itself, but penetrates into the surrounding medium of lower refractive index (cladding or air or into a surface immobilized biorecognition element) and thus senses the chemical environment on the surface of the waveguide (or fiber). In contrast to a propagating mode (oscillating electromagnetic field with the propagation constant k, defined in Chapter 2, as a real quantity), an evanescent wave has a rapidly decaying electric field amplitude, with an imaginary propagation constant k. The topic of evanescence has already been covered in detail in Chapter 7, Section 7.7.

Magnetic Resonance Imaging Of Temporal Lobe Epilepsy

The imaging axis typical for CT scanning is shown in this image. The location of the eye more laterally is approximated by the circle. This axis covers the brain in the minimum number of slices and does not directly expose the eye to radiation. This minimizes radiation exposure, particularly to the eye when compared to other axes. B. Parasagittal image showing the hippocampal axis. This Is approximately perpendicular to and along the long axis of the brain stem.

Repair of doublestrand breaks

Double-strand breaks can arise spontaneously (for example, in response to reactive oxygen species), or they can be induced by ionizing radiation. Two distinct mechanisms are used to repair these potentially lethal lesions nonhomologous end joining and homologous recombination.

Mutations Used to Determine an Anabolic Pathway

Very energetic electromagnetic radiation, such as X rays and gamma rays, as well as high-energy particles released from radioactive atoms, also induce mutations. These energetic mutagens easily penetrate cells and chemically alter many molecules in their path by stripping away electrons. Ions and radicals formed by these mutagens react with the DNA, causing bases to be released and DNA to break. DNA deletions, DNA transpositions, and DNA inversions may be promoted by DNA breakage.

Clinical Indications Background

Although atherosclerotic narrowing can affect any artery in the body, by far the most common site is the lower extremity 1-4 . In the US, arteriosclerot-ic lower limb disease is responsible for approximately 60,000 percutaneous angioplasty procedures and 100,000 amputations 4 . Because of the widespread and systemic nature of the disorder and the multiplicity of lesions that typically occurs, accurate mapping of the arterial tree is essential to guide appropriate percutaneous or surgical intervention. Although this was traditionally only possible with conventional catheter arteriog-raphy 5-7 , usually performed with a subtraction technique, recent developments in MRA now offer the potential for comprehensive non-invasive evaluation of the vasculature from above the aortic bifurcation to pedal arch. The limitation of poor spatial coverage in the cranio-caudal direction due to limited magnet bore length in relation to the large field-of-view requirement has been overcome by...

Modelling Treatment Scenarios General Comments

Itively, some combinations of therapies have been shown, for various reasons, to be less effective than each of the therapies separately. Fairly recently, it was found that ionizing radiation can inhibit chemotherapy-induced cell death (apoptosis) in certain glioblas-toma cells (Yount et al. 1998). (There have also been suggestions that antioxidants may in fact be exploited by the cancer cells to help prevent their destruction.) This type of multimodality treatment failure can be attributed to the induced mutation of cells exposed to harsh chemicals or radiation. Cancer cells are, by definition, mutated 'normal' cells, so with the accumulation of mutations, the cancerous cells progressively become more malignant and treatment-resistant. We discuss polyclonal models later when we discuss a modification of the basic model to consider chemotherapy treatment.

For Investigating Motility in the Human Digestive System

The human digestive system, particularly the small intestine, is a difficult region to access with established investigative methods. Using different methods such as X-radiography, magnetic resonance imaging (MRI) or computed tomography (CT), it is easy to visualize the morphology of the gastrointestinal (GI) tract. Unfortunately, motility cannot be investigated satisfactorily with any of these established methods as they either deal with ionizing radiation (X-ray and scintigraphy) or they are too slow to register movements. Magnetic monitoring might be that method. Here, the patient simply swallows a small magnetic marker, which then moves on its natural path through the human digestive system as a small piece of indigestible material. During the total period of investigation the marker is tracked magnetically without using any electromagnetic radiation. Magnetic monitoring has been used successfully for several years, with investigations first being conducted at centers where...

Consumer Reaction to Negative Information About Irradiation

Food and Drug Administration (FDA) has recently approved the use of ionizing radiation to control Trichinella in pork products and Salmonella in poultry. Based on its evaluation of several toxicity studies, the FDA concluded that irradiation of food products at approved levels did not present a toxicological hazard to consumers nor did it adversely effect the nutritional value of the product.

Fundamentals of radiation biology

X-rays, y-rays) is defined as radiation with sufficient energy to release electrons from the atom. The electron release damages biological tissue, principally DNA. The unit of radiation absorbed is the Gray (Gy). The Gray is defined as 1 joule of ionizing radiation absorbed by 1 kg of matter however, the Gray makes no allowance for the type of ionizing radiation. This is important as different types of ionizing radiation deliver their energy with differing spatial distribution and biological effect. Thus a-particles are 20 X more damaging than X- and y-rays. This 'quality' factor (Q) is multiplied by the absorbed dose (D) to give the 'dose-equivalent' (H). H is measured in 'sieverts' (Sv).

The Interaction of Replication Forks with DNA Damage Can Lead to Error Prone Translesion DNA Synthesis

The repair pathways considered to this point generally work only for lesions in double-stranded DNA, the undamaged strand providing the correct genetic information to restore the damaged strand to its original state. However, in certain types of lesions, such as doublestrand breaks, double-strand cross-links, or lesions in a single-stranded DNA, the complementary strand is itself damaged or is absent. Double-strand breaks and lesions in single-stranded DNA most often arise when a replication fork encounters an unrepaired DNA lesion (Fig. 25-28). Such lesions and DNA cross-links can also result from ionizing radiation and oxidative reactions.

Data Pooling And Coordinated Comparative Analysis

An evaluation of the role of residential magnetic field exposure and the risk of childhood leukemia (Greenland et al., 2000) provides a useful illustration of the value and limitations of the approach. A series of studies largely from the United States and Western Europe had evaluated the hypothesis that prolonged residential exposure to elevated levels of magnetic fields from outside power lines and electrical wiring in the home might lead to an increased risk of leukemia in children. Many methodologic concerns within each of the studies and the irregular pattern of results rendered the findings inconclusive regarding a causal relation between magnetic field exposure and cancer (NRC, 1997 Portier and Wolfe, 1998). Although there were many concerns, only one of those issues, random error, could be addressed by data pooling. In this instance, the most informative results might come from studying the occupants of homes with the very highest levels of magnetic fields, but such homes were...

For Extraterrestrial Intelligent Life

As, from our above discussions, it appears to be quite reasonable to expect the existence of a sizeable number of intelligent civilizations in our galaxy, is there a way to detect them Let us discuss the search efforts for extraterrestrial intelligence (SETI). The only practical way by which we can obtain knowledge about our surrounding universe is by electromagnetic radiation. Except for material inscribed on matter (Rose and Wright 2004), other messengers from the universe do not deliver the huge amount of information that is transmitted in the electromagnetic spectrum. Such alternate messengers are cosmic rays, charged particles, primarily protons and electrons that are produced in supernova explosions or in outbursts on the Sun, gravitational waves, which are generated by the collapse of massive stars or star mergers, and neutrinos, generated by nuclear processes in the core of stars. Today, the entire electromagnetic spectrum, ranging from gamma rays and X-rays over the...

Dna Damage By Radiation And Oxidation

It has been demonstrated repeatedly that ionizing radiation damages the DNA in cells, often leading to both chromosomal aberrations and mutations. The direct effects of ionizing radiation include breaks to single or both DNA strands, base modifications, and damage to the carbohydrate components associated with the DNA. The most important indirect effect of radiation is the production of free radicals from cellular water, which react with the DNA (reviewed in Reference 388). Tumors may develop when the cellular DNA repair mechanisms fail to detect and correct these changes or are themselves compromised. Concomitant damage to both the base and sugar moieties of the same nucleotide subunit has been studied using sample preparation techniques that release the sugars and use acidic or enzymatic hydrolyses to free the bases. The sugars have been identified and quantified by GC MS after reduction with NaBD4 to the corresponding polyalcohols, followed by silylation. The methodology has also...

Grade 3 Tibial Stress Fracture

Mri Tibula Stress Fracture

Fredericson and colleagues 56 have proposed an MRI grading system as a method of describing a continuum of stress injuries of the tibia. Grade 1 injury consists of only periosteal edema on T2-weighted, fat-suppressed images without marrow or cortical signal abnormality. Grade 2 shows both periosteal edema and marrow edema on fat-suppressed, T2-weighted images, but no corresponding decreased signal on the T1-weighted images. Grade 3 injuries show moderate to severe edema of both the periosteum and of the marrow on both the fat-suppressed T2 and the T1-weighted sequences. Grade 4 injury shows grade 3 signal changes, with the addition of the actual cortical fracture line being visible. Fredericson and colleagues recommended MRI over bone scintigra-phy as a more informative and accurate test to determine the extent of underlying bone injury, which allows better recommendations for clinical management without the exposure to ionizing radiation characterized by bone scintigraphy, along with...

Imaging Findings In Osseous Stress Injuries

MRI exhibits certain advantages over radionuclide scanning shorter scan time, no ionizing radiation, improved specificity (given the better spatial resolution of MRI), and the capability simultaneously to image bone and soft tissues. One disadvantage is its current inability to screen the entire skeleton, as is possible with radionuclide scanning.

Surface Plasmon Resonance Biosensors

Sensorgram

In principle, the SPR technique is an extension of evanescent wave sensing, described in Section 9.6, except that a planar waveguide is replaced by a metal-dielectric interface. Surface plasmons are electromagnetic waves that propagate along the interface between a metal and a dielectric material such as organic films (Wallis and Stegeman, 1986). Since the surface plasmons propagate in the frequency and wave-vector ranges for which no light propagation is allowed in either of the two media, no direct excitation of surface plasmons is possible. The most commonly used method to generate a surface plasmon wave is attenuated total reflection (ATR).

Environmental Factors

Fetal Alcohol Syndrome Vulva

Ionizing radiation kills rapidly proliferating cells, so it is a potent teratogen, producing virtually any type of birth defect depending upon the dose and stage of development of the conceptus at the time of exposure. Radiation from nuclear explosions is also teratogenic. Among women survivors pregnant at the time of the atomic bomb explosions over Hiroshima and Nagasaki, 28 aborted, 25 gave birth to children who died in their first year of life, and 25 had severe birth defects involving the central nervous system. Radiation is also a muta-genic agent and can lead to genetic alterations of germ cells and subsequent malformations.

Br J Radiol 2000 73 994-998

Performance degradation of electronic medical devices due to electromagnetic interference. Compliance Eng 1993 10(5) 25-39. 3. Silberberg, JL. What can reports of medical device electromagnetic interference tell us Compliance Eng 1997 Annual Reference Guide D17-D23. 6. Association for the Advancement of Medical Instrumentation. Guidance on electromagnetic compatibility of medical devices for clinical biomedical engineers, Part 1 radiated radio-frequency electromagnetic energy. AAMI TIRNo. 18. Arlington, Virginia, USA AAMI, 1997. 22. Kompis M, Negri S, Hausler R. Electromagnetic interference of bone-anchored hearing aids by cellular phones. Acta Otolaryngol 2000 120 855-859. 23. Gilligan P, Somerville S, Ennis JT. GSM cell phones can interfere with ionizing radiation dose monitoring equipment. Br J Radiol 2000 73 994-998. 28. Kainz W, Alesch F, Chan DD. Electromagnetic interference of GSM mobile phones with the implantable deep brain stimulator, ITREL-III. Biomed Eng...

The GVH Reaction Is an Indication of Cell Mediated Cytotoxicity

The graft-versus-host (GVH) reaction develops when immu-nocomponent lymphocytes are injected into an allogeneic recipient whose immune system is compromised. Because the donor and recipient are not genetically identical, the grafted lymphocytes begin to attack the host, and the host's compromised state prevents an immune response against the graft. In humans, GVH reactions often develop after transplantation of bone marrow into patients who have had radiation exposure or who have leukemia, immunodeficiency diseases, or autoimmune anemias. The clinical manifestations of the GVH reaction include diarrhea, skin lesions, jaundice, spleen enlargement, and death. Epithelial cells of the skin and gastrointestinal tract often become necrotic, causing the skin and intestinal lining to be sloughed.

Problems with luminal stenosis

Carotid Artery Stenosis

One further factor, not controlled for in any an-giographic study is one of projection. As shown in Fig. 1, an angiographic measure of stenosis is based on a 2D projection in the longitudinal direction of the point of maximal stenosis. Unless the luminal morphology is entirely round, this point of maximal stenosis should be better considered to be described by not one measurement, describing a circle but by two, describing an ellipse. Although more recent advances in X-ray angiography have addressed this problem with the advent of 3D rotational angiography, this is at the expense of significantly increased radiation exposure to both the patient and the radiologist. Increasingly, luminal morphology has been

Effects Of Powerfull Magnet On Humanbeings

Arsonval Great Solenoid

When investigating magnetic effects on humans, two different magnetic field ''types'' are generally distinguished (1) a static magnetic field, which exists around a large magnet and (2) a magnetic field that is pulsed at frequencies higher than 10 Hz, often abbreviated as EMF (electromagnetic fields). The study of these effects is termed biomagnetism, some sub-fields of which are highly controversial, while others have already been established in medical applications (see Chapter 2). As the 20th century began, the serious investigation of the physiologic consequences of electromagnetic fields became tainted by association with quack science and the pseudo-technology of electromedicine. Dr. Albert Adams (1863-1924), one of the controversial therapists applying electromedicine, was named ''Dean of 20th century charlatans'' by the American Medical Association. Adams postulated that each organ system and each patient were tuned to a characteristic electromagnetic wavelength. It should...

Nature Of Light 211 Dual Character of Light

Dual Character Light

The description of the nature of light provided here is at the very basic level. It serves to review the concepts that most readers already may be familiar with. Light is an electromagnetic field consisting of oscillating electric and magnetic disturbances that can propagate as a wave through a vacuum as well as through a medium. However, modern theory, quantum mechanics, also imparts a particle-like description of light as energy packets called photons or quanta (Atkins and dePaula, 2002). This dual-character description of light, which is also shared by matter as described in Section 2.2, is represented in Table 2.1. In Table 2.1, the symbol c represents the speed of electromagnetic waves, more commonly called the speed of light in a vacuum. All electromagnetic waves travel with the same speed in a vacuum. In a medium such as a glass or a biological material, the speed of an electromagnetic wave, often labeled as v, is different. The ratio of the two speeds c and v is called the...

The Eye Is a Sensor for Vision

The adequate stimulus for human visual receptors is light, which may be defined as electromagnetic radiation between the wavelengths of 770 nm (red) and 380 nm (violet). The familiar colors of the spectrum all lie between these limits. A wide range of intensities, from a single photon to the direct light of the sun, exists in nature.

Selection Bias And Confounding

For example, incidence of acute lymphocytic leukemia in childhood varies at most modestly in relation to social class, parental smoking, or any other exposures or life circumstances examined to date (Chow et al., 1996). If we wished to assess whether the incidence of childhood leukemia in the offspring of men who received therapeutic ionizing radiation as treatment for cancer was increased, the selection of an unexposed group of men might be less daunting since the variability in disease incidence appears to be independent of most potential determinants studied thus far. That is, we might be reasonably confident that rates from general population registries would be adequate or that data from men who received medical treatments other than ionizing radiation would be suitable for

Viewing Laser Radiation

Intrabeam Viewing Laser

From a safety point of view, the laser can be considered as a highly collimated source of extremely intense monochromatic electromagnetic radiation. Due to these unique beam properties, most laser devices can be considered as a point source of great brightness. Conventional light sources or a diffuse reflection of a Class 2 or Class 3 laser beam are extended sources of very low brightness because the light radiates in all directions. This is of considerable consequence from a hazard point of view, since the eye will focus the rays (400-1400 nm) from a point source to a small spot on the retina while the rays from an extended source will be imaged, in general, over a much larger area. Only when one is relatively far away from a diffuse reflection (far enough that the eye can no longer resolve the image) will the diffuse reflection approximate a point source. Diffuse reflections are only of importance with extremely high-power Class 4 laser devices emitting visible and IR-A radiation...

Power Propulsion Is a Defensive Response Against Harmful Agents

Power propulsion occurs in the retrograde direction during emesis in the small intestine and in the orthograde direction in response to noxious stimulation in both the small and the large intestines. Abdominal cramping sensations and, sometimes, diarrhea are associated with this motor behavior. Application of irritants to the mucosa, the introduction of luminal parasites, enterotoxins from pathogenic bacteria, allergic reactions, and exposure to ionizing radiation all trigger the propulsive response. This suggests that power propulsion is a defensive adaptation for the rapid clearance of undesirable contents from the intestinal lumen. It may also accomplish mass movement of intraluminal material in normal states, especially in the large intestine.

General principles of luminescence detection

When using either a photomultiplier tube or a CCD mechanism, it is important to maintain the maximum signal-to-noise ratio. Noise results from events that create an electrical signal unrelated to the light being measured. Sources of noise for a photomultiplier tube include magnetic fields, heat, electromagnetic radiation, and spurious light not emanating from the sample. An advantage of photon counting is that output from tube noise can be subtracted from the signal using electrical discrimination based on energy levels. For CCD devices, noise results mainly from the effect of heat on pixel electrons and noise inherent in the camera electronics. Heat increases the amount of statistical noise that results from the random arrival of charges on the surface of the sensor. Camera noise is additive with statistical noise.

Biologic Effects Of Radiation

Radiotherapy uses electromagnetic radiation to produce cell damage, which leads to arrest of proliferation and, ultimately, destruction of tumors. The damaging effect of radiation occurs via a cascade of ionization of events. Genomic DNA is currently considered the most important cellular target for radiation damage. Ionization at this site causes a spectrum of damage, including interstrand and intrastrand crosslinks, strand breaks, and damage to nucleotide bases. Although the processes of radiation-induced damage and repair are common to tumor and normal tissues, there are differences that can be exploited to maximize damage to the tumor with the least damage to normal tissue. This is achieved through fractionation (giving radiation dose in small divided doses) usually on a daily basis. Fractionation and the physical ability to localize radiation to tumors with less dose to surrounding normal tissue are the underlying principles of the effectiveness of radiotherapy for the treatment...

Total Internal Reflection Fluorescence Microscopy

Total Internal Reflection Microscopy

Distance of 100nm from a solid substrate. It relies on excitation of fluorescence in a thin zone of 100nm from a solid substrate of refractive index higher than that of the cellular environment being imaged, by using the electromagnetic energy in the form of an evanescent wave. The concept of an evanescent wave can be understood by using the propagation of light through a prism of refractive index n1 to the cellular environment of a lower refractive index n2. At the interface, a refraction would occur at a small incidence angle. But when the angle of incidence exceeds a value 8c, called the critical angle, the light beam is reflected from the interface as shown in Figure 7.16. This process is called total internal reflection (TIR). The critical angle 8c is given by the equation Even under the condition of TIR, a portion of the incident energy penetrates the prism surface and enters the cellular environment in contact with the prism surface. This penetrating light energy (or wave) is...

Physical Principles and Technology of Magnetic Resonance Imaging

Magnetic resonance (MR) is the phenomenon according to which particles with an angular and a magnetic moment precess in a magnetic field, thereby absorbing or emitting electromagnetic energy. This effect is called electron spin resonance (ESR) for unpaired electrons in atoms, molecules and crystals, and nuclear magnetic resonance (NMR) for nuclei. ESR was discovered in 1944 by the Russian scientist Zavoiskij (1945), but until now has not yet gained any real significance for clinical or medical applications. NMR was observed independently in 1945 by Bloch et al. (1946a) at Stanford University, in California, and Purcell et al. (1946) in Cambridge, Massachusetts. The Nobel Prize for physics was awarded in 1952 to these two American groups.

The Environment on the Early Earth

Environment The Early Earth

Oceans, lagoons, and lakes constituted aggressive chemical laboratories, in which there was evaporation, desiccation, and an infusion of large numbers of different chemical substances via fumaroles and vents, as well as ionizing radiation from radioactivity and ultraviolet light from electrical discharges caused by dust and meteoritic infalls. This energetic chemical and physical environment can be reproduced in laboratories today and the results of these experiments suggest that the oceans rapidly filled with abiotically synthesized organic compounds (Fig 3.8), and were further enriched by organic material already formed in interstellar space and brought by meteorites and comets. But with no living organisms yet present to make use of these organic compounds, they accumulated, and their concentration increased steadily to create the so-called primordial soup. It was at this point that the stage was set for the appearance of life, which is discussed in Chap. 6. Because the formation...

Accuracy of Renal MRA Techniques in Literature

Gadolinium contrast agents enormously increase the SNR allowing for higher resolution in short scan times. Using conventional angiography as a reference standard, the reported sensitivity and specificity of renal MRA with gadolinium enhancement for diagnosing renal artery stenosis are 88-100 and 70-100 respectively (Table 2) with similar interobserver variability 25 , especially for severe stenoses greater than 70 . Accuracy can be improved by evaluation of the vessel area on mul-tiplanar reformats. This requires high-resolution renal 3D CE MRA with parallel imaging. MRA thus avoids invasive diagnostic procedures 26 . In addition, renal MRA eliminates the need for aortog-raphy at the time of subsequent angioplasty 27 and thereby dramatically reduces iodinated contrast load and radiation exposure during renal revascularization. By showing the precise location of each renal artery and the angle arising from the aorta, catheter manipulation during renal revascu-larization may be...

Endovascular MRA and Intervention

Right Iliac Aneurysm

Numerous studies have been performed recently to explore the feasibility of performing endovas-cular procedures in an endovascular environment. These studies have ranged from performing basic diagnostic studies such as direct intra-arterial enhanced MRA to performing complex interventions such as iliac and renal stenting to even endovascu-lar aneurysm repair under MR guidance 19-23 . This exciting technology will undoubtedly change the way in which endovascular interventions are performed. The prospect of being able to perform endovascular procedures without exposure to ionizing radiation and the use of nephrotoxic contrast agents is quite appealing. This technology may

Diagnosis And Management

A physiologic increase in heart rate of 10-20 beats per minute (BPM) occurs during pregnancy (2), and sinus-node dysfunction is rare. Rare cases have been attributed to the supine hypotensive syndrome of pregnancy, caused by uterine compression of the inferior vena cava (IVC) blood return with paradoxical sinus slowing (67). In the rare instance when symptomatic bradycardia occurs, this should be treated with a change in position of the mother (usually a left lateral decubitus position). For persistent symptoms, a temporary pacemaker may be necessary. This can be performed safely, especially if the fetus is beyond 8 wk gestation, after which organogenesis is essentially complete and radiation exposure is of minimal risk. For patients with symptoms associated with complete heart block or other bradyar-rhythmias during pregnancy, placement of a permanent pacemaker is preferable to prolonged temporary pacing. There are recent reports of permanent pacemaker implantation during pregnancy....

Integrated Assessment Of Potential For Selection Bias In Casecontrol Studies

Whereas a perfectly coherent set of controls for a given set of cases assures freedom from selection bias, a non-coherent control group does not guarantee that bias will occur. That depends entirely on the exposure of interest and whether that exposure is related to the source of the lack of coherence. In the example regarding residential mobility and magnetic field exposure from power lines, there would be no selection bias if residential mobility were not associated with high-voltage power lines. Am J Epidemiol 1993 138 467-481. Horwitz RI, Feinstein AR. Alternative analytic methods for case-control studies of estrogens and endometrial cancer. N Engl J Med 1978 299 1089-1094. Hulka BS, Grimson RC, Greenberg RG, Kaufman DG, Fowler WC Jr, Hogue CJR, Berger GS, Pulliam CC. Alternative controls in a case-control study of endometrial cancer and exogenous estrogen. Am J Epidemiol 1980 112 376-387. Jones TL, Shigh CH, Thurston DH, Ware BJ, Cole P. Selection bias from differential...

Apply Knowledge of Confounding Based on Other Studies

To illustrate, when Wertheimer and Leeper (1979) first reported an association between residential proximity to sources of magnetic field exposure and childhood cancer, one of the challenges to a causal interpretation of the association was the potential for confounding. Because they had relied on public records, there was no opportunity to interview the parents and assess a wide range of potential confounding factors such as parental tobacco use, medications taken during pregnancy, and child's diet. When a study of the same exposure-disease association in the same community was undertaken roughly a decade later (Savitz et al., 1988), it included extensive consideration of potential confounding factors, and found essentially no indications of confounding. Although it is theoretically possible that undetected confounding due to those factors was present in the earlier study, the later study makes that possibility far less likely. That does not negate the possibility that both studies...

Interaction Mechanisms and Biological Bases for Limiting Exposure

Biological Exposure

There are well-documented bioeffects linked to excess temperature elevation. Such effects have been observed from exposure to radiofrequency (RF) electromagnetic fields resulting from whole-body or local heating. An important first step in assess- ing the RF exposure health risk is to define the level of energy absorption and the resulting possible temperature elevation over the entire frequency range. This database is fundamental to the establishment of exposure limits (ICNIRP, 1998). In addition, consideration must be given to long-term or chronic exposures of workers to low-level electromagnetic fields. In the sub-resonance range (0.1-10 MHz), exposure of the human body to electromagnetic fields can result in high rates of energy deposition in the hand, wrist and ankle due to current flow through small effective cross-sectional areas. In this frequency region, the biological response of humans arises not only from tissue heating but also from the stimulation of excitable tissues,...

Sensory Worlds Beyond Human Experience

When discussing vision, we use the term visible light, but what we really mean is light visible to humans. Our visible spectrum is a very narrow region of the entire, continuous range of electromagnetic radiation in the environment (see Figure 8.5). We cannot see ultraviolet radiation, for example, but many other animals can.

Principles Underlying Dose Limits

Radiation protection deals with the protection of individuals, their offspring, and the general population against potentially harmful effects of radiation. There are two types of cellular damage that may occur following exposure to ionizing radiation deterministic and stochastic damage 15 .

Practical Approach to Analyze Stored Electrograms

In the absence of a true tachyarrhythmia, inappropriate therapy is mainly caused by oversensing of intracardiac or extracardiac signals. Intracardiac signals that can cause oversensing include P, R, or T waves (Figure 5.3). Ventricular oversensing of intracardiac signals results in more than one detected ventricular activitiy per cardiac cycle. Dependent on the cardiac cycle, ventricular oversensing can result in inappropriate detection of ventricular tachyarrhythmias either in the tachycardia detection zone or in the fibrillation detection zone. Oversensing of intracardiac signals can be recognized by characteristics alternation of intervals and electrogram morphology separated by isoelectric baseline. Extracardiac signals include electromagnetic interference, signals generated by lead or connector problems, and myopotentials. The hallmark of oversensing of extracardiac signals is the replacement of the isoelectric baseline with high-frequency noise.

Reflection and Refraction

Reflected Wave Phenomenon

Reflection is defined as the returning of electromagnetic radiation by surfaces upon which it is incident. In general, a reflecting surface is the physical boundary between two materials of different indices of refraction such as air and tissue. The simple law of reflection requires the wave normals of the incident and reflected beams and the normal of the reflecting surface to lie within one plane, called the plane of incidence. It also states that the reflection angle 9' equals the angle of incidence 9 as shown in Fig. 2.2 and expressed by

Interactions Between Light And A Molecule 411 Nature of Interactions

As described in Section 2.1, light is an electromagnetic radiation consisting of oscillating electric and magnetic fields. Biological systems are molecular media. For such a medium the interaction with light can be described by the electronic polarization of a molecule subjected to an electric field. This approach is also referred to as the electric dipole (or simply dipole) approximation.

Evaluate Alternate Methods of Disease Grouping

Some diseases are aggregations of subgroups, in a sense demanding consideration of subtypes of a naturally heterogeneous entity. Brain cancer is defined solely by the anatomic location of the tumor, with a wide range of histologic types with varying prognosis and quite possibly varying etiology. In a rather sophisticated examination of the issue of magnetic field exposure and brain cancer in a Canadian case-control study, Villeneuve et al. (2002) hypothesized that the exposure acts as a tumor promoter and would thus show the strongest association for the most aggressive subtypes of brain cancer. Subsets of brain cancer were examined empirically (Table 9.2) and there was clear heterogeneity in pat- Table 9.2. The Risk of Brain Cancer According to the Highest Average Level of Occupational Magnetic Field Exposure Ever Received by Histological Type. Canadian National Enhance Cancer Surveillance System, Male Participants, 1994-1997 Table 9.2. The Risk of Brain Cancer According to the...

Conclusions

MR imaging is an emerging technique in this field and is expected to play a role similar to that of CT. The clinical efficacy of MR imaging has been investigated, and favorable results have been reported as described in this article. High soft-tissue contrast, static and dynamic imaging capabilities, and the absence of ionizing radiation exposure represent the advantages of MR imaging over CT. On the other hand, MR imaging is more time consuming, less readily available, and more expensive 36-39 . Advantages of CT over MR imaging include greater availability, shorter examination times, flexibility in choosing imaging thickness and planes after data acquisition with multidetector row CT, and higher spatial resolution. Precise indications for MR imaging in the diagnosis of Crohn's disease and its use as a complement to CT or other imaging procedures need further investigation. Clinical management decisions might be influenced by the presence of unsuspected additional lesions that were...

Viiicontrol Measures

Enteric virus reductions may be accomplished using ionizing radiation, ultraviolet light, and microwave energy. Ionizing radiation fragments viral nucleic acids and is becoming more generally accepted for food processing (106,107). Depending on the product, irradiation levels as high as 10 kGy have been proposed (43,108). Ionizing radiation penetrates foods to kill the microorganisms within however, ultraviolet irradiation only inactivates viruses in direct contact with the rays. Ger-micidal lamps are effective in eliminating viruses on the surface of foods. Rotavirus and poliovirus demonstrated similar rates of UV inactivation but required three to four times the dose of UV necessary to inactivate E. coli (109). No specific data are available on the effectiveness of UV irradiation on NL caliciviruses.

Types Of Studies

Most study designs contain one or more outcome variables that are specified explicitly. (Sometimes, a study design may not have an explicitly defined outcome variable but, rather, the outcome is implicit however, the use of an implicit outcome variable is not a desirable practice.) Study outcome variables may range from counts of the number of cases of illness or the number of deaths to responses to an attitude questionnaire. In some disciplines, outcome variables are called dependent variables. The researcher may wish to relate these outcomes to disease risk factors such as exposure to toxic chemicals, electromagnetic radiation, or particular medications, or to some other factor that is thought to be associated with a particular health outcome. In addition to outcome variables, study designs assess exposure factors. For example, exposure factors may include toxic chemicals and substances, ionizing radiation, and air pollution. Other types of exposure factors, more formally known as...

Overview

Plain film radiography is often the initial study obtained in the evaluation of symptoms referable to the spine. Radiographs allow for assessment of spine alignment, bone density, vertebral body height, disc height, endplate sclerosis, and osteophyte formation. The advantages of low cost and ready availability of plain radiography are, however, offset by limited soft tissue contrast, structural overlap, and relatively high radiation exposure (6,7). The cross-sectional nature of CT greatly improves the ability to resolve structures of similar density because of the lack of overlap. MRI has the additional advantages over CT of superior contrast resolution, a direct multiplanar imaging capability, and the lack of ionizing radiation. Still there are practical drawbacks to MRI related to availability, expense, length of examination, and patient claustrophobia. Several published studies have evaluated the relative accuracy of MRI, CT, and CT myelography in the diagnosis of lumbar disc...

Mass analyzers

Ii) an accelerated electric charge generates an electromagnetic field. As a consequence, we can separate charged species based on their ii) their interaction with an electrostatic (electrostatic analyzer (ESA) and orbitrap (OT)), amagnetostatic (magnetic sector (B)) and amagnetostatic and electrostatic fields (ion cyclotron resonance (ICR) analyzers), or an electromagnetic field (quadrupole (Q), three-dimensional quadrupole ion trap (3D QIT), or two dimensional linear ion-trap (LTQ) mass analyzers).

Radiation Therapy

More recently, stereotactic radiosurgery has been used in pituitary tumors to circumvent some of these problems (18-20). This uses a high dose of ionizing radiation delivered in a precisely defined, tightly concentrated field with a steep fall-off and little radiation to surrounding tissue. Details of this technique are described in Chapter 14. To date, there are limited data regarding efficacy and side effects of stereotactic radiosurgery applied to nonfunctioning pituitary adenomas. The procedure is effective in stabilizing tumor size in most patients, with frequent reports of actual tumor shrinkage. Rates of development of hypopituitarism were initially stated to be low, but further follow-up of treated patients has revealed increasing rates of hypopituitarism with time. It should be noted that hypopituitarism occurs more quickly with stereotactic radiosurgery compared with conventional radiotherapy, and these patients must be followed closely for this side effect.

Mutation

Any alteration in the nucleotide sequence that spells out a genetic message in DNA is known as a mutation. Certain chemicals and various forms of ionizing radiation, such as x-rays, cosmic rays, and atomic radiation, can break the chemical bonds in DNA. This can result in the loss of segments of DNA or the incorporation of the wrong base when the broken bonds are reformed. Environmental factors that increase the rate of mutation are known as mutagens. Even in the absence of environmental mutagens, the mutation rate is never zero. In spite of proofreading, some errors are made during the replication of DNA, and some of the normal compounds present in cells, particularly reactive oxygen species, can damage DNA, leading to mutations.

Surgical Technique

Detailed monitoring of the potential radiation hazards has shown this procedure to pose no significant risk to patients, operating room personnel, surgeons, or pathologists 3 . The soiled linens and sponges do not require special handling and can be discarded as per routine. Because sestamibi is concentrated in the heart and right upper quadrant of the abdomen, we routinely place a lead apron over the patient once they have been placed on the operating room table. This decreases radioactivity emission and thereby allows the surgeon and operating room personnel to avoid wearing radiation monitoring devices. We have estimated that the surgeon would have to perform more than 700 of these cases per year to exceed radiation exposure limits. We routinely send radioguided parathy-roidectomy patients home within an hour of the procedure. Those patients with significant underlying medical problems are kept overnight, but this is rarely necessary. All patients are sent home on supplemental...

William A Pearlman

However, the main advantage of conventional mammography is the image quality obtained at low cost. For this reason, the widespread use of digital mammogra-phy devices has been conditioned to evaluate whether the digital modality provides a better diagnostic performance over the conventional technology. Research works carrying out comparative studies have shown that digital mammography systems significantly improve detection of subtle lesions such as microcalcifications, visualization of low-contrast details or dense breast parenchymal tissue, and definition of skin.4-9 Another study comparing detection of breast cancer using hard copy images or soft copy images displayed on a high-resolution monitor found no significant differences in diagnostic interpretation or reporting speed between both modalities.10 The image processing methods included in digital mammography systems permit filtering, contrast enhancement, or other types of digital image manipulation that avoids repeating any...

Radiotherapy

The wider use of ionizing radiation in brain tumors in children has resulted in improved long-term survival. However, the significant long-term effects on cognition and growth, especially in patients requiring craniospinal irradiation (e.g., PNET), can be devastating. The total dose of radiotherapy depends on

Methodology

This epidemiological analysis includes reports on suspected EMI cases with any medical device reports from user facilities, manufacturers, voluntary sources, and distributors were included in the study. The unit of analysis was the adverse event report and a suspected EMI was defined as any report in which the event description suggested the medical device's performance was disrupted or degradedby another medical device or other equipment in the environment in which the medical device was used. This can occur when there is electromagnetic energy or EMD emitted from a source in the vicinity of the active medical device.

Discussion

In the earlier FDA study, an activated electrosurgical unit or an external defibrillator in the vicinity of the pacemaker or ICD were the most frequent potential EMD sources. In the more recent study, the most frequent non-medical EMD sources were radiated electromagnetic energy emitted from products that included wireless communication devices and security systems in public places. The different study periods and the recent proliferation of new wireless technology may explain the difference in EMD sources identified by each study. The adverse events reported in the MAUDE database mirrored the reports in the medical literature. Cellular or mobile phones were reported as potential causes of interference with a variety of medical devices. Cellular phones have been reported to interfere with implanted devices, such as a bone-anchored hearing aid 22 , monitoring devices, such as ionizing radiation dose monitoring equipment 23 , and therapeutic devices, such as mechanical ventilators 24,25...

Frequent Therapies

ELECTROMAGNETIC INTERFERENCE (EMI) Patients should be counseled to avoid sources of EMI, because it may cause the pulse generator to become inhibited, fail to deliver appropriate therapy, or deliver inappropriate therapy. Potential sources of EMI include industrial transformers, radio-frequency transmitters such as RADAR, therapeutic diathermy equipment, arc welding equipment, toy radiotransmitters, anti-theft devices such as electronic article surveillance systems, and magnetic wands. The safe use of medical technologies such as electrosur-gery, lithotripsy, external defibrillation, and ionizing radiation can be accomplished by deactivating the device prior to the event. Shielding the device is also appropriate when possible. The device should be evaluated for appropriate operation following exposure. Magnetic resonance imaging (MRI) is contraindicated. Recent reports of interference created by cellular phones may be related to either a magnetic field from within the phone or the...

Summary

Newer technologies, such as locally delivered ionizing radiation (brachy-therapy) to prevent or reduce in-stent restenosis and the use of gene-based therapy to promote neovascularization in high-risk diabetics with CAD are being explored actively. Nevertheless, we must not lose sight of the more ''traditional'' lifestyle modification interventions (weight loss, regular aerobic exercise, smoking cessation) and aggressive, multifaceted medical therapy directed toward optimized glycemic control, management of hypertension and dyslipidemia, and other secondary prevention strategies all of which, in the aggregate, are critical to enhancing improved event-free survival. This is especially important in the diabetic patient with established CAD however, the influence of aggressive primary prevention in the ''at-risk'' diabetic is equally compelling.

Artificial Nesting

The human factor may affect, directly or indirectly, the breeding success of animals. Possible biological effects of electromagnetic fields attributed to high-voltage transmission lines are suspected to reduce the reproductive success of birds whose nests are nearby, as in the case of tree swal-

Indications

MR examinations usually are performed to image joints because MR is non-invasive, has high soft-tissue contrast, and is able to image directly in the coronal and sagittal planes. Although in routine clinical practice CT has higher in-plane spatial resolution than MRI, soft-tissue contrast is limited on CT images and patients are exposed to ionizing radiation. The introduction of iodinated contrast media into the joint during an arthrogram outlines joint structures, increasing their visibility at CT imaging. CT arthrography is a slightly invasive examination with a nominal risk of contrast allergy and infection.

Absorption

Haemoglobin Absorbance 540

The terms transparent and opaque are relative, since they certainly are wavelength-dependent. Cornea and lens, for instance, mainly consist of water which shows a strong absorption at wavelengths in the infrared spectrum. Hence, these tissues appear opaque in this spectral region. Actually, no medium is known to be either transparent or opaque to all wavelengths of the electromagnetic spectrum. The ability of a medium to absorb electromagnetic radiation depends on a number of factors, mainly the electronic constitution of its atoms and molecules, the wavelength of radiation, the thickness of the absorbing layer, and internal parameters such as the temperature or concentration of absorbing agents. Two laws are frequently applied which describe the effect of either thickness or concentration on absorption, respectively. They are commonly called Lambert's law and Beer's law, and are expressed by

Genetics Mutations

In the modern era of genomics, mutations can be defined as changes in DNA (deoxyribonucleic acid) sequences, that is, changes in the structure of a gene. The changes can occur spontaneously or can be induced via ionizing radiation (ultraviolet radiation) or chemicals, such as aflatoxin B1 and ethylmethane sulfonate. A common cause of spontaneous mutations is deamination, in which the amino group on the number 2 carbon of cytosine (C) is removed, converting C to uracil (U) in DNA. Another cause is copying errors during DNAreplication slippage or shifting of the translational reading frame. Spontaneous mutations also may be caused by depurination, in which the bond between deoxyribose sugar and a purine base, adenine (A) or guanine (G), is hydro-lyzed, or by depyrimidination, the hydrolization of the bond between deoxyribose sugar and a pyrimi-dine base, either C or thymine (T). Depyrimidination is less common than depurination. The sites where a base is missing are called apurinic...

Competition

Competition is the struggle between individuals of different species (interspecific competition) or between individuals of the same species (intraspecific competition) for food, territories, and mates in order to survive. It is a major driving force in evolution, the process by which living organisms change over time, with better-adapted species surviving and less well-adapted species dying. Evolution begins with mutation, changes in the nucleotide sequence of a gene or genes, resulting in the production of slightly altered genes called alleles which encode slightly different proteins. These altered proteins are the expressed traits of an organism and may give the organism an advantage over its competitors. The organism outcompetes its rivals in the environment, and hence the environment favors the better-adapted, fitter organism, a process called natural selection. Amutation may help an organism in one environment but may hurt the same organism in a different environment (for...

Results

Electromagnetic interference can have serious adverse consequences. Some automatic implantable cardioverter defibrillators (ICDs) affected by EMI were reported to have delivered shocks when they were not needed, or to have failed to provide a shock when one was needed. In one instance, the patient had to be resuscitated after an ICD failed to shock the patient. In another case, a pacemaker was reported to have stopped during surgery. Although the patient suffered no ill-effects, this device malfunction could have resulted in serious patient injury or death. This event may have been due to EMI, electrical overstress alone, or a combination of these. Table 20.6 presents the types of medical devices most frequently affected by EMI. Implanted devices (72 ) were most frequently affected, followedby monitoring devices (12 ) and therapeutic devices (7 ). Interference with diagnostic, surgical, and prosthetic devices was infrequently reported. Table 20.7 lists the specific devices that were...

Acupuncture needles

Ancient Japan And Medicine

Other types of device interactions include the interaction of electro-acupuncture with other medical devices powered by electricity. Acupuncture practitioners often avoid using electro-acupuncture across the thorax because of the theoretical risk of interfering with the heart's conduction system. One case report described electromagnetic interference from low-frequency acupuncture on a pacemaker 20 . Therefore, caution should be exercised when using electro-acupuncture on patients with any electrically powered medical devices.

Clinical Examples

Causes Subclavian Steal Syndrome

MRI permits an excellent workup of the anatomic and physiologic status particularly as regards congenital cardiovascular malformations of the aorta. Since children or young adults most frequently require evaluation, the lack of ionizing radiation and the excellent safety profile of the applied MR contrast agents are a considerable advantage when compared with other diagnostic modalities. Moreover, since patients with congenital cardiovascular malformations need regular follow-up, it is important to reduce to a minimum the number of examinations that require ionizing radiation.

Chromosome Damage

Polytene Chromosomes

Chromosome damage probably occurs continuously in all cells. Types of damage range from single base changes, which result from mistakes made by DNA polymerases during replication, to chromosome breakage. Damage is caused by many factors, including the production of metabolic mutagens within the cells. Certain chemicals in the environment, ionizing radiation, and UV light also damage DNA and chromosomes.

Abdominal MRI

With MRI, both inflammatory changes of the bowel wall and the extramural complications of Crohn's disease can be assessed. The non-invasive-ness of this technique, as well as its lack of ionizing radiation, has prompted many groups to perform systematic studies of MRI for evaluation of Crohn's disease.

DCT angiography

Cta Carotid

Ally after the advent of multidetector helical CT (MDCT) 16 , 18 . Some authors have found it very useful for the depiction of carotid lesions, with advantages over selective angiography 8 , 24 , 26 , 31 , MRA and ultrasound sonography (US) 7 , 29 . Patients are subjected to minimal discomfort and remarkable spatial representation is possible. The technique thus allows information to be rapidly obtained about the vessel lumen, wall and surrounding structures, with low radiation exposure and at relatively little cost. Recently, neck-clipping operations for ruptured aneurysms have been performed solely with aid of 3D-CTA in many institutes 22 .

Mechanisms of Action

When microorganisms are killed by heat, their proteins (enzymes) are irreversibly denatured. Ionizing radiation results in the formation of reactive groups that contribute to chemical reactions affecting DNA and proteins. Exposure to UV light results in structural changes in DNA (thymine dimers) that prevent it from replicating. This damage can be repaired to a certain extent

Light and Matter

Scattering Reflection Absorption

In this and the following chapter, we will discuss basic phenomena occurring when matter is exposed to light. While here we will be concerned with various actions of matter on light, the opposite effect will be discussed in Chap. 3. Matter can act on electromagnetic radiation in manifold ways. In Fig. 2.1, a typical situation is shown, where a light beam is incident on a slice of matter. In principle, three effects exist which may interfere with its undisturbed propagation

Scattering

When elastically bound charged particles are exposed to electromagnetic waves, the particles are set into motion by the electric field. If the frequency of the wave equals the natural frequency of free vibrations of a particle, resonance occurs being accompanied by a considerable amount of absorption. Scattering, on the other hand, takes place at frequencies not corresponding to those natural frequencies of particles. The resulting oscillation is determined by forced vibration. In general, this vibration will have the same frequency and direction as that of the electric force in the incident wave. Its amplitude, however, is much smaller than in the case of resonance. Also, the phase of the forced vibration differs from the incident wave, causing photons to slow down when penetrating into a denser medium. Hence, scattering can be regarded as the basic origin of dispersion.

Ultrasound

An important advantage of CT is its ability to yield absolute measures of tissue densities in terms of Hounsfield units. This permits consistent thresholds to be defined for characterizing plaque content. Disadvantages of CT include the use of ionizing radiation and nephrotoxic contrast agents.

Background

The current gold standard for the diagnosis of coronary artery disease is x-ray coronary angiog-raphy. Approximately 1 million cardiac catheteri-zations are performed each year in the western world. However, x-ray coronary angiography is expensive, invasive, and requires exposure of the patients to ionizing radiation. Moreover, there is a small but finite risk of serious complications to the patient and of operator exposure to radiation. Thus, there exists a strong need for a more cost-effective, non-invasive, and more patient friendly imaging modality. Coronary magnetic resonance angiography (mRa) overcomes a lot of the problems associated with x-ray angiography and has shown great potential for the diagnosis of coronary artery disease (CAD). In addition to being non-invasive, cost effective and patient friendly, it can survey in any image plane and has the ability to achieve high spatial resolution with no exposure to potentially harmful ionizing radiation.

Vision

The Human Body Electromagnetic

The receptors of the eye are sensitive only to that tiny portion of the vast spectrum of electromagnetic radiation that we call visible light (Figure 9-20). Radiant energy is described in terms of wavelengths and Electromagnetic spectrum. frequencies. The wavelength is the distance between two successive wave peaks of the electromagnetic radiation (Figure 9-21). Wavelengths vary from several kilometers at the long-wave radio end of the spectrum to minute fractions of a millimeter at the gamma-ray end. The frequency (in hertz, the number of cycles per second) of the radiation wave varies inversely with wavelength. Those wavelengths capable of stimulating the receptors of the eye the visible spectrum are between 400 and 700 nm. Light of different wavelengths within this band is perceived as having different colors.