Electromagnetic Radiation and Human Health

How To Beat Electrical Sensitivity

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! Continue reading...

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Electromagnetic Radiation and Oxidative Stress in the Male Germ Line

Abstract The beneficial impacts of mobile-based communications on society are considerable. Health concerns over the broadcast of radio frequency electromagnetic waves, which carry the information for this medium, are now gaining momentum but are not without its controversies. Studies in the past that aim to determine whether concerns are warranted are sometimes lacking in impact because of poor understanding of radiation science. Nevertheless, the studies completed to date are important in developing the field toward the goal of confirming or disproving claims that radio frequency electromagnetic radiation (RF-EMR) is a serious health issue. We focus on what has been achieved to date, toward determining the effects of RF-EMR on the male reproductive system and information presented which may underpin the potential mechanisms at play. We suggest that oxidative stress may have a key role in the detrimental effects observed in the human spermatozoon and that this cell type may be a...

Environmental Radiation Exposure

As with the medical radiation exposure just described, environmental radiation exposure of the thyroid can be from external sources as well as internal ingestion of radioisotopes of iodine. The populations exposed are geographically related to discrete regional events involving either nuclear weapons or nuclear power plant accidents. The largest, best studied population exposed to acute external radiation from an environmental source includes survivors of the atomic bombs detonated at Hiroshima and Nagasaki.23 24 A cohort of more than 100,000 residents of these cities with a variable exposure dose on the basis of proximity to the sites of explosion has been identified and monitored. Relative risk of thyroid cancer clearly increased in this population on the basis of age at exposure and dose of radiation received. Younger people and, in particular, females younger than 30 years at the time of the blasts had the most increased relative risk. The dose response is particularly well...

Electromagnetic spectrum

X-rays are part of the electromagnetic spectrum. This is composed of energy waves. Contained within the electromagnetic spectrum are radio waves, ultraviolet light, visible light and cosmic rays, as well as X-rays and gamma rays (Fig. 32.2). Electromagnetic spectrum Fig. 32.2 The electromagnetic spectrum Fig. 32.2 The electromagnetic spectrum When electromagnetic radiation is emitted, whether it is from the sun or an X-ray tube, the intensity will decrease as the distance from the source increases. This is known as the inverse square law. This is useful in radiation protection. The further away from the X-ray tube you can get, the lower the intensity of X-rays reaching the body and causing damage.

Effects of Oscillating Radiofrequency Electromagnetic Fields B1 fields

Although the evidence regarding the teratogenic effects of MRI is confusing and contradictory, it is safer than other equivalent forms of imaging that require ionizing radiation.11 It is the imaging technique of choice in pregnant women where the alternative would involve exposure to ionizing radiation.11 Many units limit occupational exposure during pregnancy. There does not appear to be any evidence that the fields used in MRI pose an increased risk for developing cancer.

Relationship of Cell Cycle and Ionizing Radiation

The cell cycle (Figure 21-2) has four phases that are distinctly sequenced and describe the life cycle of cells (1) Synthesis (S) DNA synthesis, (2) Gap (G2) a period of apparent cellular inactivity, (3) Mitosis (M) cellular division into two daughter cells, (4) Gap (G1) a period of apparent cellular inactivity. Cells vary in their sensitivity to ionizing radiation and this is dependent on their position within the cell cycle at the time of the exposure to the radiation (Figure 21-3). The most sensitive phases are G2 and M. The medium sensitivity phases include G1 and early S. The least sensitive phase is late S (Table 21-2). In a given volume of tissue, its cells are asynchronously distributed within the various phases of the cell cycle. Each cell will progress through the cycle at its own individual rate. When exposed to ionizing radiation, the surviving cells will undergo partial synchronization. This occurs as a consequence of G2 arrest which delays cells in a more radiosensitive...

Radiation Exposure

The association between radiation exposure and increased risk of thyroid cancer was first recognized by investigators studying the increasing clinical problem of childhood thyroid cancer in the mid-20th century.5 6 The number of cases of thyroid cancer diagnosed and treated in children or adolescents was quite low only 18 cases of childhood thyroid cancer were reported in the medical literature before 1930 (Fig. 26-1).7 Duffy and Fitzgerald recognized an increased incidence of this disease and reported 28 cases between 1932 and 1948 at Memorial Sloan Kettering in New York City.5 They evaluated this population with the stated goals of highlighting this increasingly important clinical condition, defining the disease and natural history of childhood thyroid cancer, and discovering possible etiologic factors . . . from analysis of environmental, familial, and other biologic factors.5 In addition to analyzing the sex distribution of the patients, age at diagnosis in relation to puberty,...

Basic Concepts Underlying Radiation Therapy

Radiation is energy that is propagated in the form of waves or particles it is categorized as electromagnetic or particulate. Particulate radiation is the propagation of energy by traveling particles characterized by mass, momentum, and position in time examples include electrons, protons, and alpha particles. First described by Maxwell in the mid-nineteenth century, electromagnetic radiations are transverse waves consisting of oscillating electric and magnetic fields examples include x-rays, gamma rays, radiowaves, visible light, ultraviolet light, and microwaves. The energy of electromagnetic radiation is often quantized as photons, or packets. The distinction between par-ticulate and electromagnetic radiation is somewhat blurred. Sometimes photons behave more like waves and sometimes more like particles, whereas particles such as electrons and protons can exhibit wavelike properties. In general, low-energy photons, such as radiowaves, often act more like waves, and higher energy...

Radiation Processes Direct versus Indirect Effect

Radiation can be either directly or indirectly ionizing. Directly ionizing radiation, such as protons and other charged particles, produce chemical and biologic damage by directly disrupting subcellular targets such as DNA. X-rays and gamma rays, however, are indirectly ionizing. When they are absorbed in a medium, usually rich in water content, they give up their energy to produce ultra-short-lived, fast-moving charged particles and radicals that cause chemical and biologic damage. There is strong circumstantial evidence that the primary target of this damage is DNA.8

Linear Energy Transfer

Aprocess known as linear energy transfer (LET) can be a physical modifier of radiation response. LET is the average energy transferred to the medium by the ionizing particle per unit length of track. When radiation is absorbed in a medium, ion-izations tend to occur along the tracks of individual charged particles. LET is important because it is a factor in the relative biologic effectiveness (RBE) of a particular type of radiation. RBE is used to compare the biologic effectiveness of different types of ionizing radiation. Radiation can be classified as high LET, such as protons, neutrons, and heavy charged particles, or low LET, such as x-rays and gamma rays. X-rays are an example of low LET radiation with low rBe because x-rays are more sparsely ionizing and have a lower probability of causing a double-strand break. Overall, high LET radiation has the advantages of (1) higher relative biologic effectiveness, (2) less resistance of hypoxic cells, (3) less resistance in resistant...

Electroencephalogram And Magnetoencephalogram

From an electrofunctional point of view, the activity of the brain essentially translates into (1) wave-formed electromagnetic fields or potentials, which constitute the electroencephalogram and the magnetoen-cephalogram and (2) transient changes in the electromagnetic fields caused by nerve impulses induced by external stimuli or independent mental events, which constitute the event-related potentials (ERPs) and event-related fields (ERFs), respectively. It is not the aim of this review to discuss the electroencephalogram (EEG). The reader interested in the EEG and the rhythmical waves that distinguish it, as well as its origins in the cerebral cortex or in processes regulating these waves (pacemaker) in the thalamic nuclei, is referred to the excellent works by Buzsaki (1991) and Silberstein (1995a,b), as well as the impressive review by Nunez et al. (2001).

Environmentally Induced Goiter

The intake of an excessive amount of iodine inhibits thyroid peroxidase and results in the Wolff-Chaikoff effect. The normal gland is usually able to escape from this effect by inhibition of iodide uptake so that the intrathyroidal iodide level falls and organification resumes. However, in some patients with underlying thyroid disorders, the thyroid is unable to adapt to iodide excess and goiter and hypothyroidism ensue (iodide-induced myxedema). Patients at risk of goiter and or hypothyroidism due to failure to escape from iodine inhibition of thyroid hormonogenesis are those with Hashimoto's thyroiditis or those with reduced or damaged thyroid tissue after thyroidectomy or after radiation exposure to the neck.1516 Excess iodine intake in contrast media may also cause goiter with hyperthyroidism (Jodbasedow hyperthyroidism). Numerous medications also have antithyroid and goitrogenic effects. Amiodarone, which is rich in iodine (37 ), has been associated with induction of...

PET and fMRI Procedures

However, PET has no time resolution. 15O-water, the radiotracer used for activation studies, has a half-life of 2 min. Due to the long integration time of each scan, only block designs are possible. Scans of active tasks and control tasks are separated by periods of no acquisition, lasting 10 min, to allow a complete return to baseline of the activations and a complete decay of the radiotracer. Typically 8 to 12 scans are acquired, with 2 to 4 repetitions of each task. The main limitation of PET is the radiation exposure, particularly for women of fertile age and children, which limits repeated testing, and the need of a cyclotron nearby, with a high cost.

Guiding Interventions with MDCT

In other medical fields such as oncology, the use of hybrid PET-CT systems has replaced the use of either modality alone. In onco-logic applications, the benefit of integrating anatomic and functional data is clear, given the small size and large possible volume of distribution of metastatic tumors. However, in cardiology, the development of the technology has advanced before a clinical need has been clearly established. Several questions need to be answered before the clinical community in cardiology universally adopts hybrid systems Is the dual information necessary in all patients Will the cost of implementation be feasible if only a fraction of the patients having studies are using both capabilities Could both MDCT angiography and nuclear perfusion imaging be performed with limited radiation exposure Is the information obtained in a hybrid system superior to the information obtained from separate MDCT and PET or SPECT systems reviewed together We certainly...

Standardisation international ISO

Represented by DIN (Deutsches Institut for Normung). Standardisation of PPE at ISO takes place primarily in Technical Committee (TC) ISO TC 94 with a series of subcommittees (SC) for different PPE types. Certain other committees, as ISO TC 83 for sport and leisure equipment and ISO TC 42 SC 1 for noise, are also of significance for special PPE types. Table 2.7 shows the most important ISO groups related to standardisation of protective textiles and clothing. The standardisation of protective clothing especially against electric risks (shock, arcing heat, electromagnetic radiation) is carried out in general by IEC (International Electrotechnic Commission, Geneva, www.iec.ch).

Magnetic Resonance Imaging

Like CT, Magnetic Resonance Imaging or MRI (fonnerly referred to as Nuclear Magnetic Resonance imaging) was pioneered in the early 1970s. Introduced under the name Zeugmatography (from the Greek word zeugma, meaning that which draws together) it remained an experimental technology for many years. Unlike CT, RI does not use ionizing radiation to generate cross-sectional images. is considered to be a newer modality since feasible commercial development of diagnostic MRI scanners had to await affordable super-conducting magnets. Today's diagnostic systems ranges from 500,000 to 2 or 3 million.

Acquisition Analysis and Visualization

Radiologists often must balance the need for image quality with the interests of the patient. Many times the means to improving the diagnostic power of an image will mean increased dose to the patient. The factors affecting the trade-off between image quality and acceptable dose include a wide variety of concerns. For example, since the inadvertent long range biological effects (chromosomal damage) of ionizing radiation are most profound in children, pediatric radiology seldom trades increased dose for improved contrast. Similar trades are made throughout medical imaging (e.g., trading spatial resolution or increased imaging time in MRI for an improved signal-to-noise ratio). The computer scientist inter

Experimental Aspects

The microwaves are detected by a semiconducting crystal diode rectifier mounted in a waveguide. This crystal converts the high-frequency microwave electromagnetic radiation to a direct current voltage, which can then be amplified and treated by ordinary electronics. For optimum sensitivity, the detector crystal is biased with a little reflected microwave power controlled by the size of the iris, which is the coupling hole allowing the microwaves to enter the cavity. The size of this coupling hole can be simply changed with a screw tip.

Thyroid Stimulating Hormone Suppression and Miscellaneous Benign Goiters

Controversy exists in regard to the optimal management of patients both with and without palpable thyroid nodules who have been exposed to low-dose irradiation to the thyroid area. Evidence suggests that thyroid suppressive therapy is as likely to be successful in this group of patients as in those with sporadic multinodular goiter, but the main difficulty seems to be in the delineation of underlying malignancy.95 163'164 Shimaoka and coworkers163 were the first to conduct a double-blind study of suppressive treatment using T3, desiccated thyroid, or both, in irradiated patients with measurable thyroid nodules. In 1500 patients exposed with a 34 incidence of nodules and an average interval between radiation exposure and nodule detection of 27 years, TSH suppression of nodules was possible in 18 of patients over 6 months of therapy. This approach was uncontrolled, however, and made no attempt to assess the efficacy of suppression in a heterogeneous group of patients.

Diagnostic Radiography

Digital radiography has taken periapical views to a new level, enabling the practitioner to execute the treatment plan with ease and predictability. It provides accurate information regarding the site of interest. The best advancement in digital radiography is that it reduces 90 of the radiation exposure for the patient and subsequently reduces the scattered radiation levels. Digital radiography also enhances communication with patients, provides easy storage and retrieval, enables simplified electronic claims, simplifies dental staff consultation, perfects duplication, and eliminates film development chemicals and their subsequent disposal. The regular film is replaced with a sensor that is con

Incidence and Etiology

In the United States, childhood thyroid carcinoma constitutes approximately 3 of all childhood cancers. Its incidence rate is three to five cases per million per year.6-7 Childhood DTC is so uncommon that even the largest referral centers in the United States may see only two or three cases per year. It may take 35 to 50 years to develop a series of only 100 patients. Childhood thyroid cancer constitutes 3 to 4.8 of all thyroid cancers in the general population but a much larger proportion of radiation-related thyroid carcinomas.8-9 In 1950, Duffy and Fitzgerald reported a 32 incidence of low-dose head and neck irradiation in children with thyroid carcinoma, and a series reported by Winship and Rosvoll in 1970 demonstrated an 80 incidence.310 Such exposure contributed substantially to the peak in the number of patients seen from 1950 to 1965, whereas its abandonment was largely responsible for the decrease in patients by 1970. Figure 10-1 shows this referral pattern at a university...

Nuclear Magnetic Resonance

Nuclei of atoms with an odd number of protons or neutrons absorb or emit electromagnetic radiation when placed in a magnetic field. Hydrogen (protons), phosphorus 31P, sodium 23Na and carbon 13C nuclei have been studied 31P spectroscopy is used to measure concentrations of adenosine triphosphate, phos-phocreatine (PCr) and intracellular pH in muscle, and neonatal brain metabolism. Repeated examinations, e.g. of tumour PCr, may indicate progression or remission of disease.

Clinical Characteristics

Up to 39 of patients with Hurthle cell neoplasms in one study reported previous childhood head and neck radiation.11 Previous radiation exposure has also been correlated with an increase in bilaterality and multicentricity of Hurthle cell tumors, as well as an increased incidence of contralateral non-Hurthle cell malignant thyroid lesions. No genetic syndromes have been reported to be associated with Hurthle cell tumors. Other than radiation exposure and age, no other risk factors have been associated with Hurthle cell neoplasms.

Functional magnetic resonance imaging fMRI

Oxygenated arterial blood (CBF), on the outflow of O2 to the tissue (CMRO2) and on the cerebral blood volume (CBV) 15 . The magnitude of these changes in signal intensity relative to the resting conditions is color-coded to produce fMRI images that map changes in brain function, which can be superimposed on the anatomical image. This results in a spatial resolution of fMRI of 1-3 mm with a temporal resolution of approx. 10 sec. As fMRI does not involve ionizing radiation and thus is also used without limitation in healthy subjects, and allows more rapid signal acquisition and more flexible experimental set-ups, it has become the dominant technique for functional imaging. There are some advantages of PET, however -physiologically specific measures, better quantitation, better signal-to-noise ratio, fewer artifacts, actual activated and reference values - which support its continued use especially in complex clinical situations and in combination with special stimulating techniques,...

Carbon Dioxide or Bicarbonate

Allergic reactions, chronic myeloid leukemia, myeloid metaplasia, polycythemia vera, ionizing radiation, hypothyroidism, chronic hemolytic anemia, splenectomy Overwhelming bacterial infection, viral infection, drug reaction, ionizing radiation, hematopoietic diseases, hypersplenism, anaphylactic shock, cachexia, autoimmune disease

Other factors involved in responses to mechanical stimuli

Electromagnetic fields Bending and stretching of bone creates electrical fields thought to originate from the apatite crystals (piezoelectricity) (Fig. i.8.3). Electromagnetic fields generated during mechanical stimulation show distinct effects on bone. As mentioned above they reduce osteoclastic recruitment and increase osteoblastic bone formation. The response is highly frequency dependent, with frequencies below 75 Hz being most effective 24 . Magnetic field exposure inhibits cell growth through a mechanism independent of gap junctional coupling, while the alteration in alkaline phosphatase (AP) activity appears to be stimulated by electric fields independent of gap junctions 25 .

Clinical Applications Of Magnetic Resonance Imaging

Once clinical MR scanners became available certain advantages and disadvantages of their use became established. Among the chief advantages of MR are the ability to image almost any region of the body, the very high contrast available between soft tissue structures, the ability to vary the plane of imaging at will, the ability to vary the tissue appearance by varying the scan parameters, the lack of the need for any invasive step such as the injection of contrast agents, and the absence of any ionizing radiation (i.e., X rays). The relative disadvantages include the cost, time requirements, and the inability to detect certain materials. The cost of the examination varies with the time required to complete it, the number of separate images required, and other factors. A large portion of the scanner cost is associated with the magnets, which require expensive materials such as large amount of superconducting wire. Each image acquisition requires a time ranging from less than one second...

Sensory perceptions imperfections

Our human senses are impoverished when compared to those of other animals. A male moth when searching for a mate can for example respond to the 'smell' of individual molecules of the sexual attractant 'pheromone' which the female exudes into the air to lure a distant mate. Our eyes are sensitive to wavelengths in the electromagnetic spectrum between about 400 and 700 nanometres only. Many insects respond to shorter wavelengths, enabling them to use information contained in ultraviolet light. Other animals, such as some snakes, can 'see' the body heat of their prey using the long wavelengths of infrared radiation. Our hearing is similarly 3 restricted to a narrow band of frequencies. At best we can hear J' sounds up to about 20 kHz, far short of the ultrasonic frequencies r that bats use in echo locating obstacles and prey. V.

Neuroimaging Techniques Positron Emission Tomography

Positron emission tomography is expensive and not generally available even within university facilities. Scanning equipment and a cyclotron to manufacture the radiotracers are becoming less cumbersome, but still require a dedicated team of physicists and other scientists. The technique has other limitations. Hemody-namic responses follow synaptic activity by at least several hundred milliseconds, so tightly coupled physiologic studies are not feasible. Scanning during the rest or active periods must last for approximately 30 seconds when using an oxygen tracer to detect a change in perfusion of as little as 5 . Thus, an activation task must be brief. Repeated studies during the same session are limited by the total radiation exposure and the time it takes the radiotracer to no longer be detectable in the structures of interest. For example, PET-FDG studies require considerably longer times to carry out, up to 30 minutes after injection. For an activation study, the subject would have...

Single Photon Emission Computerized Tomography

Maceuticals that are given intravenously or by inhalation. Radioisotopes that emit gamma rays include xenon-133, iodine-123, and tech-netium-99m. Single photon emission computerized tomography does not directly assess neuronal function. The procedure measures cerebral perfusion, blood volume, and the distribution of several receptors, which indirectly reflect metabolism and network activity.7 Early after stroke, SPECT tends not to differentiate between viable and irreversibly ischemic tissue, because the uptake of the radiotracer is not linearly related to perfusion. For postacute ischemia studies applicable to rehabilitation interventions, SPECT's spatial resolution is just under 1 cm3. Ionizing radiation, nonuniform spatial resolution, low temporal resolution, and the relativity of measures from one region of interest to another limit its usefulness in the functional imaging of plasticity. Many of the pitfalls of SPECT are found among the methods and paradigms of components of...

Colour change mechanisms sensors we can see

The concept of producing textiles that readily vary in colour has long been anathema to the textile colourist, for whom achieving permanency of colour is a primary goal. During this search, particular colorants have shown sensitivities to light, pH, temperature, polarity of solvents, and many others.21 Indicator colorants that change colour in various conditions have already been used for a long time in chemistry. Thermochromic dyes have increasingly been the subject of investigation over the past decades for use in producing novel coloration effects in textiles as well as other applications. Such dyes can give a fast and straightforward indication of temperatures and temperature distribution. An analogous phenomenon is photochromism, where the colour will change under the influence of light. Photochromism is defined as the reversible change in colour of a chemical substance under the influence of electromagnetic radiation, such as UV light.

Activating Oncogene G Proteins

The ras oncogene encodes a 21-kd protein (p21) that functions in signal transduction from receptor proteins belonging to the tyrosine kinase family of receptors. Three ras proteins (H, K, N) exist in an active state when they are anchored to the inner membrane and bound to guanosine triphosphate (GTP) and in a resting state when they are bound to guanosine diphosphate (GDP). Activating point mutations in the ras oncogene commonly occur in codons 12 and 13 in the GTP-binding domain and in codons 59 and 61 in the guanosine triphosphatase (GTPase) domain.49 Mutations in the ras gene result in growth stimulation and the inhibition of differentiation in thyrocytes. The three ras oncogenes in thyroid tumors are randomly distributed and have a similar frequency (7 to 92 , 30 overall) (see Table 31-1). Although the ras oncogenes are the most common genetic alteration reported in thyroid neoplasms, there have been some discrepancies in the frequency of ras mutations observed in several...

Tumor Suppressor Genes

The p53 tumor suppressor gene is one of the most common genetic alterations observed in human cancers. The p53 gene, located on chromosome 17pl3, encodes a 53-kd nuclear phosphoprotein and functions as a key cell cycle regulator. p53 mutations lead to altered protein conformations that are nonfunctional and accumulate in the cell nucleus. A p53 mutation needs to occur in only one allele to lead to deregulated cellular growth. Most p53 gene mutations (98 ) occur in exons 5 through 8.643 p53 mutations are primarily present in poorly differentiated and undifferentiated thyroid cancers and in immortalized thyroid cancer cell lines (see Table 31-l).55,65'68b Radiation exposure may result in p53 point mutations.69 Increased p53 immunostaining may be useful in predicting the aggressiveness of thyroid cancers.70

Anaplastic Thyroid Carcinoma

We found no significant correlation between the presence of chromosomal aberrations and overall survival or other clinicopathologic characteristics in our investigation (see Table 36-5).8 The most common chromosomal aberrations were gains in chromosome lq21-qter in 3 of 10 anaplastic thyroid carcinomas and gains in chromosome lOp and Xp in 2 of 10 anaplastic thyroid carcinomas (see Fig. 36-7). Two of 3 anaplastic thyroid carcinomas that had a gain in lq were associated with papillary thyroid carcinoma (see Table 36-5), but neither had a known history of radiation exposure. The region of lq aberrations found in these 3 anaplastic thyroid carcinomas harbors a gene that encodes one of the receptors for the nerve growth factor (NTRK1), which is activated in about 15 of papillary thyroid carcinomas.12 Activation of NTRK1 has been reported to be present in papillary thyroid carcinomas that occur after exposure to radiation in children, as well as RET PTC chromosomal rearrangements.20-4247

Malignant Epithelial Neoplasms Mucoepidermoid Carcinoma

Mucoepidermoid carcinomas may consist of various proportions of mucous, epidermoid, intermediate, columnar, and clear cells, and are often cystic in pattern. These tumors constitute the majority of malignant neoplasms found in both major and minor salivary glands (Speight and Barrett 2002). Thus, mucoepidermoid carcinoma embodies 29 to 34 of malignant salivary gland tumors residing in both major and minor salivary glands (Ellis and Auclair 1996 Eveson and Cawson 1985 Spiro et al. 1978 Spitz and Batsakis 1984). The best evidence to date indicates that 84-93 of these neoplasms initiate within the parotid glands (Goode, Auclair, and Ellis 1998 Guzzo et al. 2002). Among the minor salivary glands, mucoepidermoid carcinoma has an affinity for the lower lip (Ellis and Auclair 1996). Generally, the mean age for these carcinomas is 47 years however, there exists a broad age range of 8 years to 92 years, and this is one of the few salivary gland malignancies occurring in childhood (Ellis and...

Neurological Applications in Diagnosis and Treatment

Diagnostic ultrasonography (US) uses sound waves above the audible level to generate diagnostic medical images. US operates on the principles of sound propagation therefore, the patient is not exposed to ionizing radiation. US has various imaging applications, with specific uses in neurological disorders. It is readily available in hospitals or outpatient imaging facilities, and it typically is less costly than other, comparable diagnostic imaging modalities. Routinely, images are obtained in real time, within a gray scale format. US uses a variety of transducers, which are available for different applications. Diagnostic US can be coupled with Doppler devices, with or without color, allowing flow measurements in vascular structures, such as commonly employed for carotid artery studies.

Basic Principles and Techniques

Ultrasonography depends on the presence of sonographic windows, which allow sound wave propagation and detection of echo signals. These signals form the basic sonographic units for image generation. Therefore, as a general rule, US is indicated when visualization of the target object is not blocked by intervening bone or air, such as calvarium or bowel gas. This limitation does not completely negate the use of US in the evaluation of adult brain disorders, as discussed later. The usefulness of US as an imaging tool in pediatrics is particularly appealing owing to its inherent lack of ionizing radiation.

Radiation Biology And Mechanism

Ionizing radiation can cause tissue damage directly and indirectly. Direct injury occurs when an ionizing particle interacts with and is absorbed by a target biologic macromolecule such as DNA, RNA, or protein enzymes. In the process of indirect injury, the ionizing radiation interacts with cellular water to form a highly reactive hydroxyl free radical. The free radicals interact and damage the biologic macromole-cules. Radiation causes different types of DNA damage change or loss of a base and breakage of the Figure 33-2. Biology of ionizing radiation. VSMC, vascular smooth muscle cell. Figure 33-2. Biology of ionizing radiation. VSMC, vascular smooth muscle cell.

Radiation Physics And Systems

Requirements for an ideal radioisotope in VBT include dose distribution of a few millimeters from the source with minimal dose gradient, low-dose levels to the surrounding tissues, treatment time of less than 10 minutes, and a sufficient half-life for multiple applications when used in a catheter-based system. Among the considerations of source selection are the source energy half-life, available activity, penetration and dose distribution, radiation exposure to the patient and the operator, shielding requirement, availability, and cost.

Understanding Beta Radiation

Beta rays are high-energy electrons emitted by nuclei that contain too many or too few neutrons. These negatively charged particles have a wide variety of energies, including transition energy, particularly between parent-daughter cells, and have a wide variety of half-lives, from several minutes (62Cu) to 30 years (90Sr 90Y). Beta emitters rapidly lose their energy to the surrounding tissue, and their range is within 1 cm of tissue. They are associated with a higher gradient to the near wall. The use of beta sources for vascular application is attractive in terms of radiation exposure and safety.

Dosimetric Considerations

Measurement standardization of ionizing radiation is essential. The dosimetry measurements determine the absorbed dose at a point in a medium. Radiation detection devices used in VBT include radiochromic film, thermoluminescence dosimeters, plastic scintil-lators, and extrapolation chambers. Isotope selection should take into account variables such as the effective energy, penetration properties, different dose gradients to the potential target areas, and the differences in the half-life across the beta and gamma isotopes. Ignoring these dosimetric considerations may result in treatment failure. A clinical example of underdosing the adventitia due to a fall in dose gradient with 90Y, which resulted in the lack of effectiveness in reduction of the restenosis rate despite the use of a centering delivery system, has been reported.41 A modification in the dose prescription, from 18 Gy to the surface of the balloon to a distance of 1.2 mm from the balloon, resulted in complete inhibition...

Epidemiology and Etiology

A number of environmental and metabolic mechanisms for Down syndrome have been evaluated, among them maternal drug, tobacco, alcohol, and caffeine use use of hormonal and nonhormonal contraceptives fluoridated water and radiation exposure. However, findings from these studies have been inconsistent. Some investigators have suggested that a possible recessive gene producing nondisjunction might explain up to 10 percent of the cases. However, studies in consanguineous marriages do not support this suggestion. Dwight Janerich and Michael Bracken (1986) indicate that the association with elevated maternal age is undoubtedly a surrogate variable for other underlying associated factors, the most important of which are probably endocrine changes associated with aging.

The wordgrounding problem

Most of us have believed at some point that the meaning of all words is explained in the dictionary. Paradoxically, this is true for many of the most difficult words, but the words that refer to qualitative experiences are ineffable and a dictionary cannot explain them, as was discussed in Chap. 5. For example, the dictionary defines red as the particular hue produced in human observers by the long wavelengths of the visible electromagnetic radiation, etc. This is a pseudo definition because neither a color-blind nor a blind born person could understand the definition nor visualize the color. The word red and the corresponding experience (phenomenal-red) must be present in our minds beforehand to establish the relationship (see Chap. 5 and Table 5.1). The key issue is that language alone does not give meaning to words. The fundamental words are grounded in qualitative experiences, which are the common phylogenetic endowment that allow us to relate to other humans and to domestic...

Treatment of the Underlying Cause of Sperm Oxidative Stress

The removal or reduction of environmental toxin exposure may require significant changes to the patient's work environment, including changing jobs where occupational exposure is unavoidable. However, simple measures such as adequate ventilation and the use of protective clothing may effectively reduce toxin exposure and improve sperm quality. Exposure to electromagnetic radiation from mobile phones can be minimised by preferably using landline phones when possible, avoiding long calls on the mobile phone and storing the mobile phone well away from the testicular area when not in use. Finally, a diet rich in antioxidant minerals (zinc, selenium) and antioxidant compounds such as vitamin C, vitamin E, carotenoids and flavonoids, all commonly present in fruit and vegetables, are likely to help augment sperm function.

Describe the standard radiographic evaluation of a patient with suspected Scheuermanns disease

Standing long cassette posteroanterior (PA) and lateral views of the spine are examined for excessive thoracic kyphosis, vertebral wedging, endplate changes, narrowing of the disc spaces, and scoliosis. The PA view should include the iliac apophyses and triradiate cartilages for evaluation of skeletal maturity. The patient should stand with his or her hips and knees fully extended. The elbows are flexed and the hands supported in the supraclavicular fossa so the arms neither flex nor extend the spine. PA radiographs decrease the radiation exposure to the breasts and heart compared with anteroposterior views. A hyperextension lateral view taken with the patient supine over a radiolucent wedge placed just caudal to the apex of the kyphosis is used to assess flexibility of the kyphotic deformity.

Whole Brain Radiation Therapy

Because, unlike microsurgery, SRS delivers ionizing radiation and will have a sterilizing penumbra of at least 1 to 2 mm outside the border of the metastasis, the risk for failure of local tumor control at the site of SRS would theoretically be lower for SRS alone versus microsurgery alone. This has

Imaging Diagnosis of Thoracic OPLL and OLF

Tomography is capable of depicting OPLL OLF over a broad area on a single film (Fig. 1b) and is useful for observing the cervicothoracic junction, whereas plain radiography is inadequate owing to the presence of the shoulder girdle. However, because of high levels of radiation exposure, computed tomography (CT) is performed more often to reconstruct the cervicothoracic junction in three dimensions.

Common types of sterilisation methods

Irradiation is an effective sterilisation method, but it is limited to commercial use only. Radiation sterilisation can be accomplished using one of two forms of radiation, either gamma radiation (electromagnetic radiation) from 60Co or 137Cs, or electron beam radiation from accelerated electrons (particle radiation). These high-energy particles or electromagnetic radiation exert their sterilising effect by inducing ionising events in the materials. The released energetic electrons collide with neighbouring atoms and create a shower of secondary electrons. These energetic electrons bombard DNA molecules in the harmful micro-organisms and induce irreversible damage to inactivate them. On the other hand, the same energetic electron shower can also induce severe damage to the material and cause mechanical or biocompatibility failures. Table 9.2 compares the two ionising energy sources (Woo and Purohit, 2002). materials. It involves the bombardment of photons and has considerable...

Photoelectron Spectra of Solids

The situation is more difficult for insulating samples. Photoionization creates positive charges within the sample that are not equilibrated immediately, and the sample becomes charged. At the same time there is usually a relatively high density of low-energy electrons close to the sample surface, which can neutralize the positive charges. The equilibrium between outgoing and incoming electrons depends on the measuring conditions, specifically on the intensity of the ionizing radiation and the cleanness of the surrounding metal parts. Therefore, the actual charging potential (Fig. 5b) depends on the measuring conditions. The charging may not even be homogeneous over the surface area investigated (differential charging), resulting in a broadening of the observed lines. Sample charging can be reduced by use of very thin samples or a separate source of low-energy electrons (flood gun). Alternatively, sample charging can be taken into account by depositing small amounts of a reference...

Angular Distribution of Photoelectrons

For a single atom or molecule, the probability of emission of an electron into a certain direction with respect to an internal coordinate system is not isotropic. It depends on the initial and final states of the photoemission process, the orientation of the electric vector E of the ionizing radiation, and the energy hv. For example, if the electron is removed from an s orbital of an atom, the probability of finding the outgoing electron under an angle with respect to E is proportional to cos2 . Thus, the probability distribution looks like an atomic p orbital. In a gaseous sample the molecules are randomly oriented with respect to a laboratory fixed coordinate system. To derive the angular distribution I( ) in the laboratory system, we must integrate over all possible orientations of the molecules. If the ionizing radiation is linearly polarized, I ( ) can be expressed as

Principles of MR imaging

MR imaging is founded on the principle that certain nuclear species, such as hydrogen, possess inherent magnetic properties. When placed in a high-strength external magnetic field these nuclei will precess, which is a resonance phenomenon, according to the axis of the external field. In order to obtain diagnostic information from these precessing protons, radiofrequency pulses are sent into the patient, which convert these nuclei to a higher energy state, by 'flipping' them from the longitudinal to the transverse plane. Once the disturbing radiofrequency (RF) pulse is turned off, thermal equilibrium is restored and the released electromagnetic energy induces a voltage in a receiver coil that is placed around the body part of interest. Based on the resistance of the imaging coil, this generates a current. This current, when sent through an analog to digital converter, creates digitized data that undergo a mathematical progression known as Fourier transformation, yielding an MR image.

Screening And Diagnostic Tests

Helical computed tomographic scanning with intravenous contrast injection (CTA) is another highly accurate noninvasive screening test for atherosclerotic RAS. Compared with the gold standard, CTA has a sensitivity between 90 40 and 98 41 and a specificity between 94 41 and 97 40 for the diagnosis of RAS (> 50 stenosis). The test performance increases if only the main renal arteries are considered (sensitivity 100 , specificity 97 ).40 The test performance decreases in patients with compromised renal function,41 in those with fibromuscular disease,33,34 and in populations without clinical features suggestive of atherosclerotic RAS.33,34 High-grade stenoses may appear as occlusions in both CTA and MRA. Other disadvantages include large-volume contrast requirements, prolonged breath-hold, and significant radiation exposure.

Duplex Ultrasonography

Duplex ultrasonography has largely replaced invasive venography for the diagnosis of DVT. It has many positive features there is no requirement for neph-rotoxic contrast agents, the test is noninvasive, and there is no need for ionizing radiation. In addition, it is widely available and can be performed at the bedside. Duplex ultrasonography has high sensitivity and specificity for peripheral (jugular, distal subcla-vian, axillary) UEDVT.75 However, acoustic shadowing from the clavicle limit visualization of a segment of subclavian vein and may result in a false-negative study.76

Disturbances in Calcium and Phosphate

The primary factor driving increases in circulating calcium is PTH, which increases bone resorption and converts vitamin D3 (cholecalciferol) into 1,25-dihydroxycholecalciferol, the active form of vitamin D3. Cholecalciferol is primarily formed in the skin from solar irradiation, and some evidence suggests that ultraviolet (UV) radiation exposure of tanning beds can raise vitamin D3 (Tangpricha et al., 2004). Dietary sources are

Radiologic Characteristics

RT is universally recommended for a patient older than age 5 with a high-grade thalamic glioma following pathologic confirmation. Although dependent on actual tumor distribution, use of conformal radiation schemes is advised. Most therapeutic approaches for children with malignant thalamic astrocytomas include chemotherapy. This multimodality approach, namely, radiation combined with multiagent chemotherapy, is based on the concept of reducing the total radiation exposure and creating a synergistic tumoricidal effect. For a child younger than age 5, neoadjuvant chemotherapy is recommended in an effort to delay RT.

Photonic Bandgap Materials

Transport of electromagnetic radiation can be manipulated using photonic bandgap materials, which contain periodic structures with sufficiently high dielectric contrast. In this case the transport of visible light may be totally or partially suppressed 156,157 . There are, however, several important problems to be solved before this potential can be fully realized. One of these is the large periodicity required (order of X 4, where X is the wavelength of the electromagnetic radiation used). Several methods have been introduced to form photonic bandgaps, such as lithographic and etching techniques 158 , colloidal self-assembly 159 , synthetic opals 160-162 , and inverted opals 163,164 . Block copolymer self-assembly is another obvious possibility 165-168 . However, a large periodicity requires high molar mass block copolymers, which are notoriously difficult to prepare in a single crystal-like state. Here the comb-shaped supramolecules concept may have some advantages as well. Apart...

Anatomy Of The Left Atrial Appendage Embryology

Morphologic changes occur in the LAA after exposure to ionizing radiation. Generalized collagen (fibrosis) develops in rat hearts exposed to radiation, with reduction of appendage volume and loss of elasticity. These changes appear to negatively influence ventricular function,21 because evidence suggests that the LAA plays a role in LV filling and contributes to normal cardiac function.22-25

Etiology of Minor Salivary Gland Tumors

Benign and malignant salivary gland tumors have also been linked to exposure to ionizing radiation related to the atomic bombings in Hiroshima and Nagasaki during World War II. One hundred forty-five salivary gland tumors have been studied in survivors of these bombings (Saku, Hayashi, and Takahara et al. 1997). One hundred nineteen major gland tumors (27 malignant tumors, 82 benign tumors, 10 undetermined tumors) and 26 minor gland tumors (14 malignant tumors, 12 benign tumors) were identified. Among the 41 malignant tumors, the frequency of mucoepider-moid carcinoma was disproportionately high, and among the 94 benign tumors, the frequency of Warthin's tumor was high.

PMC in Patients with High Surgical Risk

During pregnancy, surgery carries a substantial risk of fetal mortality and morbidity, especially if extra-corporeal circulation is required. The experience of PMC during pregnancy is still limited48,49 but suggests the following. From a technical point of view, during the last weeks of pregnancy (which was the time of PMC in most cases), the procedure may be more difficult because of the enlarged uterus. The Inoue technique seems to be particularly attractive in this setting, because the fluoroscopy time is reduced and the short inflation-deflation cycle probably reduces the hemodynamic compromise. The procedure is effective and results in normal delivery in most cases. Regarding radiation exposure, PMC is safe for the fetus, provided that protection is provided by a shield that completely surrounds the patient's abdomen and the procedure is performed after the 20th week. In addition to radiation, PMC carries the potential risk of related hypotension and the always-present risk of...

Definition of Radiation

Radiation is energy which is emitted from atoms and is transmitted through space.1 It is the capture of this energy emanating from physical reactions occurring at an atomic level and its application to cellular material which results in biologic change that forms the scientific basis of the specialty of radiation oncology. There is a broad spectrum of radiation types, however the particular one of clinical interest is known as ionizing radiation. This is defined as radiation of sufficient energy that when applied to an atom is capable of dislodging an orbiting electron that can subsequently cause a biologic effect when it interacts with cellular components such as H2O or DNA.

Types of Therapeutic Radiation

There are two main categories of ionizing radiation and each contains several subtypes of clinical importance (1) electromagnetic radiation (photons) x-rays, gamma rays, and (2) particulate radiation electrons, neutrons, protons. The electromagnetic radiation subtypes do not differ in any physical characteristic or in their biologic action. The only distinction is in how they are each produced. X-rays are created by linear accelerators and involve an electrical input that causes a filament to become heated and which serves as a source of electrons. These electrons are then accelerated and are administered to a patient as particulate radiation or are directed to strike a tungsten target which results in

Improving the Therapeutic Ratio

The use of multiple fractions over many weeks of radiation therapy is based on the principle of improving the therapeutic ratio between normal tissues and tumors (Table 21-3). The goal is to maximize the cell death of tumors and to minimize unacceptable damage to normal cells. The radiobiologic mechanisms involved with causing cell death are similar for both normal and malignant cells. It is the differential ability of ionizing radiation to sterilize tumor while avoiding excessive normal tissue damage that forms the basis of clinical radiation oncology. This is accomplished through the use of multiple fractions and is explained by the four

Transcranial Magnetic Stimulation

Transcranial magnetic stimulation is not a new idea. In 1896, the French engineer Arsenne d'Arsonval applied TMS over the retina and induced phosphenes. In 1910. Pollacsek and Beer filed a patent in Vienna to use magnetic stimulation for the treatment of depression. However, it wasn't until the 1990s that the technology became sufficiently developed to allow induced electromagnetic fields that caused cortical neuron depolarization. TMS relies on Faraday's law of electromagnetic induction (Bohning, 1999). The TMS capacitor discharges high-amplitude electric current in the TMS coil and in turn generates a magnetic field, up to 20,000 times that of the earth, which passes unimpeded and very focally through the scalp. The magnetic field then induces a secondary electric field in the brain. In effect, the magnetic field gets converted to the electrochemical energy that directly depolarizes superficial neurons (at a maximum depth of 2 mm) and indirectly influences pathways to which these...

Weathering Of Polymers

Weathering is a broad term that is applied to the changes that take place in a polymer on exposure out of doors. The main agents of weathering are sunlight (particularly ultraviolet radiation), temperature, thermal cycling, moisture in various forms, and wind. The main degradation is brought about by ultraviolet light, assisted by contributions from the visible and near-infrared portions of the electromagnetic spectrum. In particular the near-infrared radiation accelerates degradation reactions by raising the temperature.

Anaesthesia For Radiological Procedures

Healthcare workers are exposed to X-rays in the radiology and imaging suites. The greatest source is usually from fluoroscopy and digital subtraction angiography. Ionizing radiation from a CT scanner is relatively low because the X-rays are highly focused. Radiation intensity and exposure decrease with the square of the distance from the emitting source. The recommended distance is 1-2 m. This precaution, together with lead aprons and thyroid shields, keep exposure to a safe level.

Magnetic Resonance Imaging General principles

Magnetic resonance imaging (MRI) is an imaging modality that does not use ionizing radiation, but depends on magnetic fields and radiofrequency pulses for the production of its images. The imaging capabilities of MRI are superior to those of CT for examining intracranial, spinal and soft tissue lesions. MRI can differentiate clearly between white and grey matter in the brain, thus making possible the in vivo diagnosis of demyelination. It can display images in the sagittal, coronal or transverse planes and, unlike the CT scanner, is capable of detecting disease in the posterior fossa. It has the advantage that no ionizing radiation is produced.

Anaesthetic management

There are other unique problems presented by MRI. These include relative inaccessibility of the patient and the magnetic properties of the equipment. The body cylinder of the scanner surrounds the patient totally manual control of the airway is impossible and tracheal intubation or laryngeal mask airway is essential. The patient may be observed from both ends of the tunnel and may be extracted quickly if necessary. As there is no hazard from ionizing radiation, the anaesthetist may approach the patient in safety. MRI-guided surgery is a new, highly specialized form of surgery that may continue to be developed. It offers surgeons radiological images of the tissues immediately beyond their operative field. This is made possible by the development of an open configuration scanner as opposed to the traditional closed tubular scanner. The open configuration consists of upright paired coils between which the medical staff can access the patient. The absence of ionizing radiation places less...

Camouflage concealment and deception

Concealment of personnel to avoid visual detection by eye or photography is still the primary means of military surveillance and target acquisition (Vickers, 1996). However, modern battlefield surveillance systems may operate in a wide waveband of the electromagnetic spectrum, including UV, near infra-red (NIR), far infra-red (FIR), radar in the millimetric or centimetric band, and acoustic ranges. Table 21.8 shows details of the threat wavebands and the detection systems used. Textiles are widely used as camouflage media in the form of light, flexible nets, covers, and garnishing, as well as dyed or printed clothing items. Textiles are lightweight, durable, cheap, and can be manufactured in a wide

Serendipity and Synchronicity

On the other hand, Wilhelm Rontgen's discovery of X-rays, in 1895, exemplified Type 1 serendipity. While attempting to detect cathode rays from an evacuated glass tube fitted with a black cardboard sheath (P1), he noticed that a distant cardboard screen coated with barium platinocyanide fluoresced with each discharge of the tube, regardless of which side of the screen the tube faced. The anomalous energy penetrated the black cardboard sheath and operated at distances beyond the effective range of cathode rays in air (E(x)). He realized that he was witnessing a new phenomenon. He later used it to record a skeletal image of his wife's hand on a photographic plate (P2) confirming the existence of X-rays. Rontgen's discovery exemplifies Type 1 serendipity. He never intended to discover a new form of electromagnetic radiation and the problem (skeletal imaging) was original.

Nuclear Power And Uncertainty

Many estimates and evaluations of nuclear power involve scientific and probabilistic uncertainty. There is, for example, uncertainty regarding actual radiation exposure levels, particular people's sensitivity levels, the likelihood of dangerous consequences in a specific case, the given causal chains of harm, and so on. U.S. Department of Energy (DOE) representatives admit that Chernobyl could cause up to 28,000 fatal cancers in the former Soviet Union, Scandinavia, and Europe over the next 50 years. Other scientists and policy makers claim that the number of fatal cancers caused by Chernobyl will be as high as 475,000. Also, U.S. Nuclear Regulatory Many assessors evaluating nuclear-related risks in situations of factual or probabilistic uncertainty follow traditional norms of avoiding false positives (type-I error) rather than avoiding false negatives (type-II error). For example, the International Atomic Energy Agency (IAEA) and the International Commission on Radiological...

Female breast anatomy

With increasing age, and especially after the menopause, the glandular elements of the breast become less prominent and tend to be replaced by adipose tissue (fat). Fat attenuates the beam less than glandular breast tissue as a result, fatty breast is darker. Significant disease (which tends to be dense and produce high attenuation or bright areas on the film) is detected more easily. Younger breast tissue is denser (whiter), and the sensitivity of mammography in patients under 50 years of age is thus reduced. The younger breast is also more sensitive to the adverse effects of ionizing radiation, so ultrasound is often used as the first-line investigation in younger patients, especially under 35 years of age.

What is vertebroplasty

Vertebroplasty is the percutaneous injection of polymethylmethacrylate (PMMA) into a vertebral body to provide stabilization and relief of pain. The procedure was introduced in the 1980s, initially for treatment of vertebral hemangiomas. Currently, the procedure is most commonly used to treat acute and subacute osteoporotic vertebral body compression fractures. The procedure is performed with local anesthetic, with or without intravenous sedation, or with general anesthesia. The patient is placed prone on a radiolucent table and positioned to optimize fracture alignment. High-quality, high-resolution fluoroscopy is required and biplane fluoroscopy is preferable. Following placement of a needle into the vertebral body through either a pedicular or extrapedicular approach, bone cement mixed with barium contrast is introduced into the vertebral body with fluoroscopic monitoring. Multiple small syringes are commonly used to introduce the PMMA into the access needle. Alternatively, use of...

What Practitioners Say It Does

Electric current and electromagnetic field applications are used by some practitioners to treat ulcers, burns, nerve and spinal cord injuries, diabetes, gum infections in dentistry, asthma, heart disease, and other maladies. One type of therapy involves placing an antenna in the patient's mouth, through which low-level electromagnetic energy is administered to treat insomnia and hypertension. A magnetic pulse generator is used in lieu of electroconvulsive therapy (informally known as electroshock) to treat depression and seizures. Scientific data do not support the effectiveness of magnetic or electric fields in the diagnosis or treatment of disease. It is ironic that electromagnetic therapies are being promoted today as alternative cures for cancer and other diseases, as international scientific research is simultaneously examining the possibility that even very weak electromagnetic fields can promote cancer in some body cells.

Recommended reading

The production of an image of an affected area of the body is a useful diagnostic tool and can be achieved by radiography, ultrasound, nuclear scintigraphy, computed tomography and magnetic resonance imaging. Radiography is the most common method and makes use of the fact that X-rays, which are part of the electromagnetic spectrum, will create a permanent image on radiographic film.

Sensing and Detection

Oversensing is defined as sensing of unintended nonphysiological signals or physiological signals that do not accurately reflect local depolarization.1 Nonphysiological signals usually arise from extracardiac electromagnetic interference. Electrical artifacts are a common cause of oversensing from leads with insulation failure or intermittent fracture resulting in make-break potentials. Physiological signals may be intracardiac (P, R, or T waves) or extracardiac (myopotentials). Oversensing often results in characteristic patterns of near-field (pace-sense) and far-field (shock) electrograms (EGMs).2'3 In ICD patients, most oversensing results in detection of sufficiently rapid signals that inappropriate detection of ventricular fibrillation (VF) occurs. Oversensing accounts for approximately one third of inappropriate shocks in studies of chronic ICD systems.4 The second requires use of digital signal processing technology to discriminate true R waves from oversensed events. For...

Treatment and Outcomes

Percutaneous device closure has proved effective in the repair of ASDs, with minimal morbidity and essentially no mortality. Closure rates are comparable to those of surgery over similar time periods (97 to 99 at 12 months), but procedural morbidity is considerably lower.105,110 Percutaneous closure avoids the necessity of a sternotomy, cardiopulmonary bypass, and mediastinal and chest-tube drainage, but it does have the disadvantage of limited exposure to ionizing radiation. Fluoroscopy times are brief (< 4 minutes), and low-dose adjustments can be used. The risk of device embolization is small and in most cases is related to operator inexperience. The incidence of this complication is approximately 0.1 .106,107 The majority of acute complications have been related to rhythm disturbances, in most cases atrial flutter or intermittent supraventricular tachyarrhythmia. However, these complications are also rare, occurring less than 1 of the time. Thrombus formation on the device, with...

Quasiexperiments casecontrol studies and cohort studies

To test the hypothesis that 'childhood leukaemia and non-Hodgkin's lymphoma can be caused by fathers' exposure to ionising radiation before the conception of the child, and more generally, to investigate whether such radiation exposure of either patient is a cause of childhood cancer'. These included (a) parental employment as radiation worker before conception of child, (b) cumulative dose of external ionizing radiation for various of periods of employment before conception of child, and (c) dose during pregnancy.

Screening and Diagnosis

Screening of family members of affected individuals should consist of biochemical tests of thyroid C cell and adrenal medullary function as well as imaging studies where indicated. A 1991 consensus statement of the European Community Concerted Action Medullary Thyroid Carcinoma group recommended annual basal and pentagastrin- or calcium-provoked serum calcitonin determinations in this group of patients, beginning at age 3 years and continuing until age 35 years, after which the frequency could be decreased owing to greatly diminished yield.33 The criteria for diagnosis on the basis of serum calcitonin elevation were discussed previously. Confusion may be noted in attempts to diagnose medullary thyroid carcinoma biochemically in children because serum calcitonin levels could be high in the young in the absence of disease.34 Currently, individuals suspected of MEN 2B are tested for zet mutation if they have the zet mutation, prophylactic total thyroidectomy is recommended.35,36 To...

Inappropriate Detection Due to Oversensing

ICD sensing circuits are designed to be highly sensitive so that low amplitude EGM waveforms during fibrillation can be sensed adequately.5 As a result, oversensing of cardiac and noncardiac signals in ICDs occurs and is one of the major sources of inappropriate ICD therapy. Oversensing on the ventricular sensing channel of an ICD (ventricular oversensing) causes inappropriate VT VF detection due to overestimation of the true cardiac rate. Oversensing on the atrial sensing channel (atrial oversensing) may lead to failures of dual chamber SVT discriminators to properly withhold VT VF detection during SVT. Ventricular oversensing is generally a much more serious clinical concern than atrial oversensing, as it is more likely to result in inappropriate ICD therapy. Analyses of long-term studies of chronically implanted ICDs have reported that 7-11 of all ICD-detected VF episodes were due to ventricular oversensing of the intrinsic rhythm.95'97 The most commonly reported sources of...

Pediatric and Other Congenital Applications

There are settings where interventional MRI may have value even in straightforward catheter-based procedures. The advantages of MRI might include avoiding radiation or iodinated radiocontrast or reducing operator musculoskeletal injury from lead aprons. Children with congenital cardiovascular abnormalities are subjected to multiple catheter procedures during their lifetime and may accumulate a large radiation exposure with excess malignancy risk. Schalla, Higgins, Moore, and colleagues at the University of California San Francisco conducted comprehensive diagnostic cardiac catheterization procedures in swine with atrial septal defect (Fig. 64-10), using active-tracking catheters containing microcoils. They traversed right-sided and left-sided In landmark work, the team at Kings College London tested these techniques in humans using a combined XMR suite. They used MRI and passive gas-filled balloon-tipped catheters to conduct diagnostic cardiac catheterization in children, to avoid...

Use Of X Rays For Materials Characterization

X rays are a short-wavelength form of electromagnetic radiation discovered by Wilhelm Roentgen in 1895. X-Ray-based techniques provided important tools for the theoretical physicist in the first half of this century, and since the early 1950s they have found an increasing use in the fields of materials characterization. Today, the analytical techniques based on X-ray diffraction and X-ray spectrometry, both of which were first conceived almost 70 years ago, play a vital role in the analysis and study of inorganic and organic solids.

Melanin In The Photoprotection Of Skin

Melanin can absorb electrons, as has been observed for some cation-exchange polymers, and its ion-exchange activity plays an important role in the biological system when skin is exposed to sunlight or ionizing radiation (241). Studies on this characteristic property of melanin by different authors revealed the mechanism of photoprotection and broadened our knowledge regarding melanin color.

Effects of laundering on UV protection

Zhou and Crews53 did a more comprehensive study on the effect of repeated launderings on UVR transmission through fabrics. In their study, eight types of woven and knitted summer wear fabrics ranging from a 100 cotton sheeting to blends of cotton polyester to a 100 nylon were subjected to 20 launderings using detergents with and without an optical brightening agent (OBAs). Optical brightening agents are additives found in home laundry detergents to enhance the whiteness of textiles. Since OBAs function by excitation in the UV band and re-emission in the visible blue band of the electromagnetic spectrum it stood to reason that fabrics laundered with a detergent containing an OBA would likely have enhanced sun protection. As expected, all the woven and knit cotton fabrics in the study showed an increase in UPF and decrease in percent UVR transmission after repeated launderings using a detergent with OBA. The positive results were attributed partly to the high absorbent properties of...

Identification of Sperm Oxidative Stress from Clinical History

Male Infertility Causes Mnemonics

Cancer and its treatment by chemotherapy and radiation are known to be a potent systemic oxidative insult, potentially impairing sperm function. Drugs such as the chemotherapy agent cyclophosphamide have been linked with sperm oxidative stress. Administration of cyclophosphamide to animals is reported to increase testicular malondialdehyde (MDA) levels and produce a fall in testicular catalase, implying the presence of oxidative stress 86, 87 . Similarly, radiation exposure has been shown to cause a systemic inflammatory reaction and increase in oxidative stress in both the irradiated tissue and non-irradiated bystander normal tissue 88, 89 . DNA fragments of apoptotic irradiated cancer cells are released into the intercellular space and interact with the DNA-binding receptors of the bystander non-irradiated cells, initiating activation of lymphocyte signalling pathways associated with synthesis of reactive oxygen and nitrogen species, thereby inducing secondary oxidative stress 90 ....

Mitochondrial ROS and Spermatozoa 2211 Mitochondrial ROS Production

While these studies do not provide causative evidence for a link between DYm and ROS generation, it is further supported in a subsequent study by De Iuliis et al. 52 , which found that the 8-hydroxy-2'-deoxyguanosine (8OHdG) formation in human spermatozoa is negatively associated with DYm. To further emphasize such a relationship, exposure of purified human spermatozoa to electromagnetic radiation (EMR) results in significant increases in mitochondrial ROS and 8OHdG formation, which are highly correlative with each other (R2 0.727) 53 . While no study to date has analyzed the correlation between all three factors, mitochondrial ROS, DYm, and oxidative DNA damage, these data combined does suggest all three have significant relationship.

Modalities for Imaging the Adrenal Gland

MRI is increasingly used because it can reveal tissue-specific characteristics, which allows the examiner to differentiate metastases, adrenocortical carcinoma, and pheochromocytoma from adenoma, lipoma, myelolipoma, and cysts.4 Because MRI does not use ionizing radiation, it is an attractive modality for evaluating children and pregnant women.5 T1-weighted images allow relatively fast data acquisition, which may be accelerated by using paramagnetic contrast media such as acid (DTPA), resulting in a reduction of motion artifact and increasing the sensitivity for identifying adrenal lesions. T2-weighted sequences reveal characteristic signal intensities in certain conditions and help with the differential diagnosis.6 Some studies have suggested that MRI can differentiate nonfunctioning from malignant adrenal lesions,6 but because of similar characteristics of some tumors, the results are not reliable enough to use in selecting therapy.6,7 the presence of abundant intracellular...

Bipolar And Monopolar Recordings

In bipolar montages all electrodes are connected together in chains, with the second input to one channel becoming the first input to the next channel. The most common use of a bipolar montage is to record the electrooculogram. In this case horizontal eye movements are recorded by means of two electrodes placed at the external canthus of the left and right eyes, and blinks and vertical eye movements are recorded by means of two electrodes placed below and above the right eye, with a bipolar montage. In a monopolar montage, also called a common reference method, one electrode is active and the other one (or two electrodes linked together) acts as a reference electrode. Typical arrangements for the reference electrode(s) are the linked ears and the linked mastoids configurations. The reference lead must be as electrically neutral as possible with regard to brain activity, while it nevertheless records the basic activity underlying the various...

Differentiated Thyroid Cancer of Follicular Cell Origin

Contemporary gamma cameras are optimized for imaging at the emission energy of 99mTc (140 keV) rather than much higher emission energies of l3lI (364 keV) or the lower emission energy of 201T1 (69 to 81 keV). Tc 99m sestamibi has the advantage of the availability of a kit-based radiopharmaceutical with same-day imaging. The other advantage of Tc 99m sestamibi over 20IT1 is a short physical half-life of 6 hours, whereas 201T1 has a physical half-life of 73 hours. Therefore, Tc 99m sestamibi can be administered in a larger dose (20 to 25 mCi), resulting in better images and lower radiation exposure to the patient.

General Considerations

A lack of patient motivation should lead to a decision to extract those questionable teeth before radiation therapy. Radiation exposure, type, field, and dosage also are parts of the decision formula regarding extraction of teeth. Usually not all of the mandibular teeth are included in the radiation portal. For example, teeth and anterior mandible between the mental foramen in radiation for base of tongue tumors receive less than 3,000 cGy, (absorbed bone dosage), and are thus at a very low risk for osteora-dionecrosis. On the other hand, posterior mandibular teeth receive a much higher dose of radiation.

What are some of the side effects of hormonal therapy and how are they treated

How can you tell if you have osteoporosis The best way to check the bone mineral density is the dual-energy x-ray absorptiometry (DEXA) scan, the same study used to evaluate for osteoporosis in women. It is noninvasive, precise, and a quick test involving minimal radiation exposure. The test measures the bone mineral density, which is compared with values obtained from normal, young, adult control subjects.

Trior to matinib therapy Epidemiology And Etiology

The incidence of CML increases with age, with the median age of diagnosis in the fifth decade of life.1 In most newly diagnosed cases, the etiology cannot be determined but high doses of ionizing radiation and exposure to solvents such as benzene are recognized risk factors.

Inflammatory Conditions in the Gonad Oxidative Stress

Oxidative stress arises, among others, due to the exposure of the gonads to toxins, chemotherapy, ionizing radiation, bacterial inflammation, cryptorchidism, or pathology of veins in the spermatic cord (varicocele) 39 . The Leydig cells are physiologically and sometimes physically connected with macrophages, which makes possible their direct exposure to the growth factors and or differentiation factors which are secreted by macrophages. It was shown that in physiological conditions macrophages produce and secrete 25-hydroxycholesterol which stimulates the Leydig cells to produce testosterone 40, 41 . In inflammatory conditions, however, macrophages are activated by, e.g., LPS and produce proinflammatory cytokines,

What are externalbeam and conformal externalbeam radiation therapies What are the side effects of EBRT

The genitourinary symptoms of dysuria, frequency, hesitancy, and nocturia are related to changes that occur in the bladder and urethra that result from radiation exposure. The bladder may not hold much urine because of the irritation and scarring, and irritation of the bladder lining may make it more prone to bleeding. Bladder inflammation usually occurs about 3 to 5 weeks into the radiation treatments and gradually subsides about 2 to 8 weeks after the completion of radiation treatments. Urinary anesthetics (phenazopyridine HCL Pyridium ) and bladder relaxants (antimuscarinic agents) may be helpful in decreasing the urinary frequency.

Ancyclostoma Brazillienses Force Out Of The Skin

Neurotrophic Joint Xray Foot

Figure 20-79 shows a subungual presentation of malignant melanoma of the hallux. Determine the cause of all subungual pigmented lesions. Unusual pigmentation under the nail, especially if of long duration, should always be regarded with suspicion. Subungual melanomas represent approximately 20 of melanomas in dark-skinned and Asian populations, in comparison with about 2 of cutaneous melanomas in white populations. Ultraviolet radiation exposure seems to be an important risk factor for cutaneous melanoma however, because ultraviolet radiation is unlikely to penetrate the nail plate, it does not appear to be a risk factor for subungual melanomas. There is a considerable predominance of subungual melanoma localized on the thumb (58 of all affected fingers) and the hallux (86 of all affected toes).

Autosomal Recessive Inheritance

Ataxia and telangiectasias of the bulbar conjunctivae, malar eminences, ear lobes, and upper neck increased increased of respiratory infections, Iymphomas, Hodgkins disease, acute leukemia, and a variety of cancers thymus gland is hypoplastic or absent there is decreased IgA and IgG increased chromosomal breakage and increased sensitivity to ionizing radiation of fibroblasts and Iymphocytes

Angle Resolved Photoelectron Spectra

A different situation occurs if a molecule is adsorbed at a surface and thereby fixed in space. For example, consider a rodlike molecule (e.g., CO) which, for a given final state M+, emits electrons preferentially in the direction of the molecular axis. In addition, assume that the emission probability is proportional to cos2 of the angle between molecular axis and electric vector E of the ionizing radiation. The system is fully described by three angles and the polarization of the radiation. The three angles are shown in Fig. 7a is the angle between the surface normal n and the propagation direction s of the radiation, 0 is the angle between n and the direction D of the outgoing electron, and is the angle between the ns plane and the nD plane. Usually 2 is called the incidence angle, 0 the polar angle, and the azimuthal angle. The important difference between free or space-fixed single molecules and periodic structures is as follows. In the first case, the intensity of the peaks in...

Electrical protection

Radiation from electro-magnetic fields (EMF) generated by power lines is another potential risk to people working near power lines. There have been reports about the relation between exposure to electromagnetic fields and health hazards like leukemia and brain cancer (Adanur, 1995). A typical electromagnetic protective fabric is woven from conductive material such as spun yarns containing a mixture of fire-retardant textile fibers and stainless steel fibers (8-12 micron diameter). It has been shown that fabrics made of 25 stainless steel fiber 75 wool blend or 25 stainless steel fiber 75 aramid fiber blend can protect the wearer from electromagnetic fields generated by voltages of up to 400 kV (Adanur, 1995). Protection at even higher voltages can be obtained by using a combination of these fabrics in two or more layers (King, 1988).

Predisposing factors to developing cancer

As society becomes more affluent, so the incidence of cancer can be demonstrated to rise. There could be a number of explanations for this, including increased wealth and improved health care enabling individuals to achieve a greater life expectancy than their grandparents (Gabriel, 2001). People are also surviving previously life-threatening illnesses, such as infectious diseases, major accidents, etc., only to live longer and possibly to develop cancer later in life. We also know that more affluent societies consume higher amounts of convenience foods, alcohol and tobacco, as well as being exposed to higher levels of chemicals and pollutants compared with people living in some less developed parts of the world. All these factors can contribute to an individual developing a malignancy (Venitt, 1978 Cartmel and Reid, 2000 Corner, 2001). Other factors can include past exposure to ionizing radiation, viruses and a genetic disposition (Cartmel and Reid, 2000 Yarbro, 2000a).

Studies on EMR and Male Infertility

Fig. 1.2 Proposed oxidative stress model of the effects of mobile phone frequency radiation on the human spermatozoon. Evidence suggests that, like several other factors, radio frequency electromagnetic radiation (RF-EMR) can induce a non-thermal oxidative stress response in the gamete, possibly through interactions with NAD(P)H oxidases in the plasma membrane or by perturbation of mitochondria. This stress then leads to the range of adverse effects commonly observed under experimental conditions Fig. 1.2 Proposed oxidative stress model of the effects of mobile phone frequency radiation on the human spermatozoon. Evidence suggests that, like several other factors, radio frequency electromagnetic radiation (RF-EMR) can induce a non-thermal oxidative stress response in the gamete, possibly through interactions with NAD(P)H oxidases in the plasma membrane or by perturbation of mitochondria. This stress then leads to the range of adverse effects commonly observed under experimental...

Stage I seminoma surveillance versus treatment

The testicular germinal epithelium is exquisitely sensitive to ionizing radiation so that in an effort to maintain hormonal and reproductive function in the remaining testis, scrotal shielding is routinely used. Despite this, some radiation scatter is still experienced and persistent oligo-spermia has been reported in 8 42 . There seems to be no increase in the incidence of children who have genetic anomalies born to men who have undergone radiation treatment of testic-ular malignancy 43 .

Tomographic Imaging Techniques

MRA has the advantage over CTA (and catheter-based angiography) in that it does not use ionizing radiation or nephrotoxic contrast dye. Gadolinium-enhanced magnetic resonance angiography (GEMRA) is the most useful MRI technique for assessing PAD. Its sensitivity and specificity for detecting occlusive arterial disease is greater than 95 (compared with catheter-based DSA). It is also highly sensitive and specific for assessing vascular wall inflammation. Phase-contrast MRA is a separate technique that provides simultaneous anatomic and functional data, similar to duplex ultrasonography. Phase-contrast MRA can quantify flow across a stenosis or a shunt and can measure turbulence. It is not typically included in MRI protocols at most institutions, so it must be specifically ordered. but is more widely available, less operator dependent, and less susceptible to artifact. Less patient cooperation is necessary compared with MRI, and claustrophobia and prolonged breath-holding are less...

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