Achondroplasia Glossary of Terms
Abnormal: Not normal. Deviating from the usual structure, position, condition, or behavior. In referring to a growth, abnormal may mean that it is cancerous or premalignant (likely to become cancer ).
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Achondroplasia : The most common form of short stature with disproportionately short limbs -- dwarfism with short arms and legs. Achondroplasia is caused by mutation in the fibroblast growth factor receptor-3 gene (FGFR3), which is located on chromosome 4 in chromosome band 4p16.3.
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Amniocentesis : Procedure used in prenatal diagnosis to obtain amniotic fluid which can be used for genetic and other diagnostic tests. Informally called an "amnio."
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Arms: An appendage in anatomy and in clinical trials. See: Arm.
Autosomal: Pertaining to a chromosome that is not a sex chromosome; relating to any one of the chromosomes save the sex chromosomes.
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Autosomal dominant: A pattern of inheritance in which an affected individual has one copy of a mutant gene and one normal gene on a pair of autosomal chromosomes. (In contrast, autosomal recessive diseases require that the individual have two copies of the mutant gene.) Individuals with autosomal dominant diseases have a 50-50 chance of passing the mutant gene and therefore the disorder onto each of their children. Examples of autosomal dominant diseases include Huntington disease, neurofibromatosis, and polycystic kidney disease.
Brain: That part of the central nervous system that is located within the cranium ( skull ). The brain functions as the primary receiver, organizer and distributor of information for the body. It has two (right and left) halves called "hemispheres."
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Brainstem: The lowest part of the brain which merges with the spinal cord and provides the major route by which the upper realms of the brain send information to, and receives information from, the spinal cord and peripheral nerves. The brainstem consists of the medulla oblongata, midbrain, and pons. All but two of the 12 cranial nerves originate in the brainstem. The brainstem influences basic processes such as alertness, breathing, blood pressure, and heart rate.
Breathing: The process of respiration, during which air is inhaled into the lungs through the mouth or nose due to muscle contraction, and then exhaled due to muscle relaxation.
Bridge: A set of one or more false teeth supported by a metal framework, used to replace one or more missing teeth.
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Cartilage: Firm, rubbery tissue that cushions bones at joints. A more flexible kind of cartilage connects muscles with bones and makes up other parts of the body, such as the larynx and the outside parts of the ears.
Chest: The area of the body located between the neck and the abdomen . The chest contains the lungs , the heart and part of the aorta . The walls of the chest are supported by the dorsal vertebrae , the ribs , and the sternum .
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Chromosome: A visible carrier of the genetic information.
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Chromosome band: One of the transverse bands produced on chromosomes by differential staining techniques. Depending on the particular staining technique, the bands are alternating light and dark or fluorescent and nonfluorescent.
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Compression: 1. The act of pressing together. As in a compression fracture, nerve compression, or spinal cord compression.
2. To shorten in time. In embryology, there may be compression of development with some stages even omitted.
Conception: 1. The union of the sperm and the ovum. Synonymous with fertilization.
2. The onset of pregnancy, marked by implantation of the blastocyst into the endometrium.
3. A basic understanding of a situation or a principle.
From the Latin conceptio, conceptionis meaning conception, becoming pregnant; drawing up of legal formulae; and from the Latin conceptus meaning conceiving, pregnancy; collecting, or a collection.
Decompress: 1. In general, to remove pressure physically or emotionally.
2. In surgery, to remove pressure on a structure such as the spinal cord.
3. To lessen atmospheric pressure on deep-sea divers returning to the surface, or on persons ascending to great heights.
Diagnosis: 1 The nature of a disease ; the identification of an illness. 2 A conclusion or decision reached by diagnosis. The diagnosis is rabies . 3 The identification of any problem. The diagnosis was a plugged IV.
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Drain: A device for removing fluid from a cavity or wound. A drain is typically a tube or wick. As a verb, to allow fluid to be released from a confined area.
Ear: The hearing organ. There are three sections of the ear, according to the anatomy textbooks. They are the outer ear (the part we see along the sides of our head behind the temples), the middle ear, and the inner ear. But in terms of function, the ear has four parts: those three and the brain. Hearing thus involves all parts of the ear as well as the auditory cortex of the brain. The external ear helps concentrate the vibrations of air on the ear drum and make it vibrate. These vibrations are transmitted by a chain of little bones in the middle ear to the inner ear. There they stimulate the fibers of the auditory nerve to transmit impulses to the brain.
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Ear tubes : Formally known as tympanostomy tubes, ear tubes are small plastic tubes inserted into the eardrum (the tympanum) to keep the middle ear aerated for a prolonged period of time. To put the tubes in place, a myringotomy (a surgically placed tiny incision in the eardrum) is done. Any fluid, usually thickened secretions, will be removed. The ear tubes usually remain in place for 6 months to several years. Water should not be allowed to enter the ear canal while the tubes are in place. Eventually, they will move out of the eardrum (extrude) and fall into the ear canal. The doctor may remove the tube during a routine future office visit or it may simply fall out of the ear without the child realizing it.
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Elbow: The juncture of the long bones in the middle portion of the arm. The bone of the upper arm (humerus) meets both the ulna (the inner bone of the forearm) and radius (the outer bone of the forearm) to form a hinge joint at the elbow. The radius and ulna also meet one another in the elbow to permit a small amount of rotation of the forearm. The elbow therefore functions to move the arm like a hinge (forward and backward) and in rotation (outward and inward). The biceps muscle is the major muscle that flexes the elbow hinge, and the triceps muscle is the major muscle that extends it. The primary stability of the elbow is provided by the ulnar collateral ligament, located on the medial (inner) side of the elbow. The outer bony prominence of the elbow is the lateral epicondyle, a part of the humerus bone. Tendons attached to this area can be injured, causing inflammation or tendonitis (lateral epicondylitis, or tennis elbow). The inner portion of the elbow is a bony prominence called the medial epicondyle of the humerus. Additional tendons from muscles attach here and can be injured, likewise causing inflammation or tendonitis (medial epicondylitis, or golfer's elbow). See also: Elbow bursitis ; Elbow pain ; Nursemaid's elbow.
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Essential: 1. Something that cannot be done without.
2. Required in the diet, because the body cannot make it. As in an essential amino acid or an essential fatty acid.
3. Idiopathic. As in essential hypertension. "Essential" is a hallowed term meaning "We don't know the cause."
Father: (1) The male parent. (2) One who originates. For example, "Wilhelm Roentgen is considered the father of radiology." (3) To produce offspring as a male. (4) To provide paternal protection and guidance to children.
FGFR3: Abbreviation for fibroblast growth factor receptor 3. Mutations in the FGFR3 gene are known to cause three different syndromes -- hypochondroplasia, achondroplasia, and thanatophoric dysplasia. These syndromes represent variations in severity. Hypochondroplasia is the mildest and thanatophoric dysplasia (also called thanatophoric dwarfism) is the most severe. In fact, thanatophoric dysplasia is a type of dwarfism in which death usually occurs in the first hours of life. FGF3 is an example of how different syndromes can result from mutations in a single gene.
Fibroblast: A cell ubiquitous in connective tissue that makes and secretes collagen.
Foramen: A natural opening. Although a foramen is usually through bone, it can be an opening through other types of tissue, as with the foramen ovale in the heart. The plural of foramen is foramina.
Foramen magnum: The large hole at the base of the skull which allows passage of the spinal cord.
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Frontal: In anatomy, pertaining to the forehead. As, for example, the frontal bone, frontal sinus, and frontal nerve. From the Latin "frons" meaning the forehead or brow.
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Gene: The basic biological unit of heredity . A segment of deoxyribonucleic acid (DNA) needed to contribute to a function.
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Genes: The basic biological units of heredity . Segments of deoxyribonucleic acid (DNA) needed to contribute to a function.
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Genetic: Having to do with genes and genetic information.
Genu: The Latin word for the knee. When the knee is referred to in medicine, it is just called the knee. However, the word "genu" is also used in medicine as in: genu recurvatum (hyperextension of the knee), genu valgum (knock knee) and genu varum (bowleg).
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Growth hormone: A hormone made in the pituitary gland that stimulates the release of another hormone called somatomedin by the liver, thereby causing growth. Also known as somatotropin. Growth hormone is produced by the anterior pituitary gland, the front section of the gland, and is a polypeptide that consists of 191 amino acids . Growth hormone is given to children with pituitary dwarfism (short stature due to underfunction of the anterior pituitary) to help them grow. Excessive growth hormone production in children can lead to gigantism, and in adults it can lead to acromegaly.
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Heterozygous: Possessing two different forms of a particular gene , one inherited from each parent. A person who is heterozygous is called a heterozygote or a gene carrier.
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Homozygous: Possessing two identical forms of a particular gene, one inherited from each parent.
Hormone: A chemical substance produced in the body that controls and regulates the activity of certain cells or organs.
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Hydrocephalus: Hydrocephalus is an abnormal buildup of cerebrospinal fluid (CSF) in the ventricles of the brain. The fluid is often under increased pressure and can compress and damage the brain.
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Hypoplasia: Underdevelopment or incomplete development of a tissue or organ. For example, there can be hypoplasia (underdevelopment) of the enamel of the teeth. Hypoplasia is less drastic than aplasia where there is no development at all.
Hypotonia: Decreased tone of skeletal muscles. In a word, floppiness. Hypotonia is a common finding in cerebral palsy and other neuromuscular disorders. Untreated hypotonia can lead to hip dislocation and other problems. Treatment is via physical therapy. In some cases braces may be needed to permit a full range of movement despite hypotonia.
Intervention: The act of intervening, interfering or interceding with the intent of modifying the outcome. In medicine, an intervention is usually undertaken to help treat or cure a condition. For example, early intervention may help children with autism to speak. "Acupuncture as a therapeutic intervention is widely practiced in the United States," according to the National Institutes of Health. From the Latin intervenire, to come between.
Joint: A joint is the area where two bones are attached for the purpose of motion of body parts. A joint is usually formed of fibrous connective tissue and cartilage. An articulation or an arthrosis is the same as a joint.
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Kyphosis: Outward curvature of the spine, causing a humped back.
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Laminectomy: A surgical procedure in which the posterior arch of a vertebra is removed. Laminectomy is done to relieve pressure on the spinal cord or on the nerve roots that emerge from the spinal canal. The procedure may be used to treat a slipped or herniated disk or to treat spinal stenosis.
Limb: The arm or leg.
Lordosis: Inward curvature of the spine. Normally, for example, the low back demonstrates lordosis. The spine is not supposed to be absolutely straight, so some degree of curvature is normal. When the curve exceeds the usual range, it may be due to musculoskeletal disease or simple poor posture. Treatment is usually by physical therapy, although in severe cases surgery, casting, and/or bracing may be required. Also known as swayback.
Lumbar: Referring to the 5 lumbar vertebrae which are situated below the thoracic vertebrae and above the sacral vertebrae in the spinal column. The 5 lumbar vertebrae are represented by the symbols L1 through L5. There are correspondingly 5 lumbar nerves.
Megalencephaly: Also called macrencephaly, a condition in which there is an abnormally large, heavy, and usually malfunctioning brain. By definition, the brain weight is greater than average for the age and gender of the child. Head enlargement may be evident at birth or the head may become abnormally large in the early years of life.
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Middle ear: There are three sections of the ear. They are the external ear, the middle ear, and the inner ear. The middle ear consists of the ear drum (the tympanum or tympanic membrane) and, beyond it, a cavity. This cavity is connected via a canal (the Eustachian tube) to the pharynx (the nasopharynx). The Eustachian tube permits the gas pressure in the middle ear cavity to adjust to external air pressure (so, as you're descending in a plane, it's the Eustachian tube that opens when your ears "open"). The middle ear cavity also contains a chain of 3 little bones (ossicles) that connect the ear drum to the internal ear. The ossicles are named (not the Nina, the Pinta and the Santa Maria, but) the malleus, incus, and stapes. In terms of function, the middle ear communicates with the pharynx, equilibrates with external pressure and transmits the ear drum vibrations to the inner ear.
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Motor: In medicine, having to do with the movement of a part of the body. Something that produces motion or refers to motion. For example, a motor neuron is a nerve cell that conveys an impulse to a muscle causing it to contract. The term "motor" today is also applied to a nerve that signals a gland to secrete. Motor is as opposed to sensory.
Muscle: Muscle is the tissue of the body which primarily functions as a source of power. There are three types of muscle in the body. Muscle which is responsible for moving extremities and external areas of the body is called "skeletal muscle." Heart muscle is called "cardiac muscle." Muscle that is in the walls of arteries and bowel is called "smooth muscle."
Mutant: An individual with a mutant (changed) gene.
Mutation: A permanent change, a structural alteration, in the DNA or RNA . In humans and many other organisms, mutations occur in DNA. However, in retroviruses like HIV , mutations occur in RNA which is the genetic material of retroviruses.
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Nasal: Having to do with the nose. Nasal drops are intended for the nose, not (for example) the eyes. The word "nasal" came from the Latin "nasus" meaning the nose or snout.
Obesity: The state of being well above one's normal weight.
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Ossification: The process of creating bone, that is of transforming cartilage (or fibrous tissue) into bone.
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Overweight: The term "overweight" is used in two different ways. In one sense it is a way of saying imprecisely that someone is heavy. The other sense of "overweight" is more precise and designates a state between normal weight and obesity .
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Ovum: An egg in the ovary of the female. This egg is called the female "gamete" or sex cell. It combines with the male gamete, called a sperm, to form a zygote. This formation process is called "fertilization." (see sperm, zygote).
Paternal: 1. Pertaining to the father as, for example, a paternal age effect.
2. Related through the father as, for example, the paternal grandparents.
3. Inherited from the father as, for example, the paternal X chromosome.
Paternal age: The age of the father at the time he conceives a child. The present mean (average) paternal age is 27 years in the US population. Advanced paternal age is clearly associated with an increased risk of new mutations, a risk that rises linearly with the age of the father. See: Advanced paternal age.
Pediatric: Pertaining to children.
Pelvis: The lower part of the abdomen located between the hip bones.
Pregnancy : The state of carrying a developing embryo or fetus within the female body. This condition can be indicated by positive results on an over-the-counter urine test, and confirmed through a blood test, ultrasound, detection of fetal heartbeat, or an X-ray. Pregnancy lasts for about nine months, measured from the date of the woman's last menstrual period (LMP). It is conventionally divided into three trimesters, each roughly three months long.
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Pregnant: The state of carrying a developing fetus within the body.
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Prenatal: Occurring or existing before birth.
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Prenatal diagnosis: Diagnosis before birth. Methods for prenatal diagnosis include ultrasound of the uterus, placenta, and/or developing fetus; chorionic villus sampling (CVS) to obtain tissue for chromosome or biochemical analysis; and amniocentesis to obtain amniotic fluid for the analysis of chromosomes, enzymes, or DNA. A growing number of birth defects and diseases can be diagnosed prenatally, and in some cases treated before birth. Also known as antenatal diagnosis.
Protein: A large molecule composed of one or more chains of amino acids in a specific order determined by the base sequence of nucleotides in the DNA coding for the protein.
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Proximal: Toward the beginning, the nearer of two (or more) items. For example, the proximal end of the femur is part of the hip joint, and the shoulder is proximal to the elbow. The opposite of proximal is distal.
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Radiology: The branch of medicine that uses ionizing and nonionizing radiation for the diagnosis and treatment of disease.
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Receptor: 1. In cell biology, a structure on the surface of a cell (or inside a cell) that selectively receives and binds a specific substance. There are many receptors. There is a receptor for ( insulin ; there is a receptor for low-density lipoproteins ( LDL ); etc. To take an example, the receptor for substance P, a molecule that acts as a messenger for the sensation of pain , is a unique harbor on the cell surface where substance P docks. Without this receptor, substance P cannot dock and cannot deliver its message of pain. Variant forms of nuclear hormone receptors mediate processes such as cholesterol metabolism and fatty acid production. Some hormone receptors are implicated in diseases such as diabetes and certain types of cancer. A receptor called PXR appears to jump-start the body's response to unfamiliar chemicals and may be involved in drug-drug interactions.
2. In neurology, a terminal of a sensory nerve that receives and responds to stimuli.
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Respiration: 1. The act of inhaling and exhaling air in order to exchange oxygen for carbon dioxide. Synonymous with breathing and ventilation. 2. The cellular metabolic process by which oxygen is taken in, substances are oxidized, energy is released, and carbon dioxide and oxidized products are given off.
Shunt: 1) To move a body fluid, such as cerebrospinal fluid, from one place to another. 2) A catheter (tube) that carries cerebrospinal fluid from a ventricle in the brain to another area of the body. A shunt may be placed to relieve pressure from hydrocephalus, for example.
Skeletal: Pertaining to the skeleton, the bones of the body which collectively provide the framework for the body.
Skull: The skull is a collection of bones which encase the brain and give form to the head and face. The bones of the skull include the following: the frontal, parietal, occipital, temporal, sphenoid, ethmoid, zygomatic, maxilla, nasal, vomer, palatine, inferior concha, and mandible.
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Sperm: A sperm is the male "gamete" or sex cell. It combines with the female "gamete," called an ovum, to form a zygote. The formation process is called "fertilization." (see ovum, zygote).
Spinal cord: The major column of nerve tissue that is connected to the brain and lies within the vertebral canal and from which the spinal nerves emerge. Thirty-one pairs of spinal nerves originate in the spinal cord: 8 cervical , 12 thoracic , 5 lumbar, 5 sacral, and 1 coccygeal. The spinal cord and the brain constitute the central nervous system ( CNS ). The spinal cord consists of nerve fibers that transmit impulses to and from the brain. Like the brain, the spinal cord is covered by three connective-tissue envelopes called the meninges . The space between the outer and middle envelopes is filled with cerebrospinal fluid ( CSF ), a clear colorless fluid that cushions the spinal cord against jarring shock. Also known simply as the cord.
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Spinal cord compression: The act of exerting an abnormal amount of pressure on the spinal cord. Compression of the spinal cord may, for instance, be due to a fracture of the spine or a tumor pressing on the spinal cord.
Spinal stenosis: Narrowing of the spaces in the spine, resulting in compression of the nerve roots or spinal cord by bony spurs or soft tissues, such as disks, in the spinal canal. This occurs most often in the lumbar spine (in the low back) but also occurs in the cervical spine (in the neck) and less often in the thoracic spine (in the upper back).
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Sporadic: Occurring upon occasion or in a scattered, isolated or seemingly random way.
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Stenosis: A narrowing, as in: - aortic stenosis (narrowing of the aortic valve of the heart),
- pulmonary stenosis (narrowing of the pulmonary valve of the heart),
- pyloric stenosis (narrowing of the outlet of the stomach), and
- spinal stenosis (narrowing of the vertebral canal).
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Surgery: The word "surgery" has multiple meanings. It is the branch of medicine concerned with diseases and conditions which require or are amenable to operative procedures. Surgery is the work done by a surgeon. By analogy, the work of an editor wielding his pen as a scalpel is s form of surgery. A surgery in England (and some other countries) is a physician's or dentist's office.
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Trait: In genetics, a trait refers to any genetically determined characteristic. In technical terms, a genetic trait is amenable to segregation analysis rather than quantitative analysis.
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Trauma: Any injury , whether physically or emotionally inflicted. "Trauma" has both a medical and a psychiatric definition. Medically, "trauma" refers to a serious or critical bodily injury, wound, or shock . This definition is often associated with trauma medicine practiced in emergency rooms and represents a popular view of the term. In psychiatry , "trauma" has assumed a different meaning and refers to an experience that is emotionally painful, distressful, or shocking, which often results in lasting mental and physical effects.
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Tubes: The "tubes" are medically known as the Fallopian tubes. There are two Fallopian tubes, one on each side, which transport the egg from the ovary to the uterus (the womb). The Fallopian tubes have small hair-like projections called cilia on the cells of the lining.
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Ultrasound: High-frequency sound waves. Ultrasound waves can be bounced off of tissues using special devices. The echoes are then converted into a picture called a sonogram. Ultrasound imaging, referred to as ultrasonography, allows physicians and patients to get an inside view of soft tissues and body cavities, without using invasive techniques. Ultrasound is often used to examine a fetus during pregnancy. There is no convincing evidence for any danger from ultrasound during pregnancy.
Varum: See: Varus.
Villus: 1. A tiny finger-like or hair-like projection. 2. A small vascular protrusion.
Villus is the Latin word for shaggy hair or fleece. The plural is villi.
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X-ray: 1. High-energy radiation with waves shorter than those of visible light. X-rays possess the properties of penetrating most substances (to varying extents), of acting on a photographic film or plate (permitting radiography), and of causing a fluorescent screen to give off light (permitting fluoroscopy). In low doses X-rays are used for making images that help to diagnose disease, and in high doses to treat cancer . Formerly called a Roentgen ray. 2. An image obtained by means of X-rays.
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- Ultrasound - Learn an ultrasound procedure, and conditions and diseases it assists in diagnosing and screening like tumors, cysts, heart conditions and more.
- Hydrocephalus - Learn about hydrocephalus (water on the brain) causes like brain trauma, stroke, infection, tumor, and more.
- Ear Tubes - Learn about ear tubes (myringotomy), a procedure that allows ventilation in the middle ear. Pre-surgery, during surgery, post surgery, and follow-up information is included.
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