B
Bo the symbol used for the static main magnetic field, in magnetic resonance imaging, which is orientated along the x axis and measured in Tesla.
B1 the symbol used for radiofrequency magnetic field, in a magnetic resonance imaging system, and measured in Tesla.
Babinski’s reflex or sign movement of the great toe upwards (dorsiflexion) instead of downwards (plantar flexion) on stroking the sole of the foot. It is indicative of disease or injury to upper motor neurons. Babies exhibit dorsiflexion, but after learning to walk they show the normal plantar flexion response.
bacillaemia the presence of bacilli in the blood.
bacille Calmette–Guörin a form of tubercle bacilli; it has lost its power to cause tuberculosis, but retains its antigenic function; it is the base of a vaccine used for immunization against tuberculosis. Also used in urology for the treatment of high-risk superficial bladder cancer.
bacillus colloquial term for any rod-shaped microorganism.
Bacillus a type of bacteria consisting of aerobic, Gram-positive, rod-shaped cells that produce endospores. The majority have flagella and are motile. The spores are common in soil and dust.
Bacillus anthracis bacteria which cause anthrax in humans and domestic animals.
Bacillus cereus bacteria which produce exotoxins and cause food poisoning. It can occur after eating cooked food, for example, rice, that has been stored prior to reheating.
back pointer used in radiotherapy to indicate the central exit point of the radiation. See also front pointer.
back projection mathematical basis for tomographic imaging. In CT scanning in order to overcome the blurring inherent in this method a filtered back projection is used, resulting in a sharper image.
back scatter radiation that having passed through the object hits a surface, for example the couch, and is reflected back onto the original object.
bacteraemia the presence of bacteria in the blood.
bacteria microscopic unicellular organisms widely distributed in the environment. Pathogens may be virulent and always cause infection, whereas others, known as opportunists, usually only cause infection when the host defences are impaired, such as during cancer chemotherapy. Non-pathogenic bacteria may become pathogenic if they move from their normal site, for example, intestinal bacteria causing a wound infection. Bacteria are classified and identified by features that include: shape and staining characteristics with Gram stain (positive or negative). Bacteria may be: (a) round (cocci), paired (diplococci), in bunches (staphylococci) or in chains (streptococci); (b) rod-shaped (bacilli); or (c) curved or spiral (vibrios, spirilla and spirochaetes).
bacterial associated with bacteria.
bactericidal describes agents that kill bacteria, for example, some antibiotics.
bactericidin antibody that kills bacteria.
bacteriologist an expert in bacteriology.
bacteriology the scientific study of bacteria.
bacteriolysin a specific antibody formed in the blood that causes bacteria to break up.
bacteriolysis the disintegration and dissolution of bacteria.
bacteriophage a virus parasitic on bacteria. Some of these are used in phage-typing staphylococci, etc.
bacteriostatic describes an agent that inhibits bacterial growth, for example, some antibiotics.
bacteriuria the presence of bacteria in the urine (100000 or more pathogenic microorganisms per millilitre). Acute cystitis may be preceded by, and active pyelonephritis may be associated with, asymptomatic bacteriuria.
Bainbridge reflex stretch receptors in the heart (right atrium) can increase heart rate through sympathetic stimulation when venous return increases.
Baker’s cyst a cyst that forms at the back of the knee. Often associated with rheumatoid arthritis and may appear only when the leg is straightened.
balance of probabilities the standard of proof required in civil proceedings.
balanitis inflammation of the glans penis.
balanitis xerotica obliterans (BXO) inflammatory condition involving the glans and prepuce.
balanoposthitis inflammation of the glans penis and prepuce.
balanus the glans of the penis or clitoris.
ball and socket joint a type of synovial joint with a wide range of movement, for example shoulder joint.
ball catcher’s projection an anteroposterior oblique projection of both hands.
bandage material applied to a wound or used to bind an injured part of the body. May be used to: (a) retain a dressing or splint; (b) support, compress, immobilize; (c) prevent or correct deformity. Available in strips or circular form in a range of different materials and applying varying levels of pressure. compression bandages are widely used in the management of venous leg ulceration.
bandwidth the difference between the maximum and minimum frequency in a system. A range of frequencies in magnetic resonance. See also receiver bandwidth, transmitter bandwidth.
Bankart’s operation for recurrent dislocation of the shoulder joint: the defect of the glenoid cavity of the scapula is repaired.
barbiturates a group of sedative/hypnotic drugs. They are associated with serious problems of dependence and tolerance, and sudden withdrawal may cause a serious withdrawal syndrome that includes anxiety, convulsions and even death. They have been replaced by safer drugs and their use is limited to anaesthesia and sometimes for epilepsy.
barbotage a method of extending the spread of spinal anaesthesia whereby local anaesthetic is directly mixed with aspirated cerebrospinal fluid and reinjected into the subarachnoid space.
bar chart a graph displaying the data in columns, which are separate from each other.
barium enema a radiographic examination of the large bowel using barium sulphate as the contrast agent. Barium sulphate liquid, followed by a quantity of air, is introduced into the large bowel by means of a rectal tube, during fluoroscopy. It is used for diagnostic purposes, for example, for colon cancers, in conjunction with endoscopy. See also barium sulphate, colonoscopy.
barium meal (barium swallow) a radiographic examination of the upper gastrointestinal tract (oesophagus and stomach) and the small intestine with follow-through radiographs, using barium sulphate as the contrast agent. The barium sulphate suspension is swallowed and radiographs are taken of the gastrointestinal tract. Pre-examination fasting is required and medicines, for example, some antacids, that may interfere with the examination should be stopped. Further fasting may be required until follow-through radiographs are completed.
barium sulphate a heavy insoluble powder used, in an aqueous suspension, as a contrast agent in radiographic visualization of the alimentary tract by either being introduced orally, via the rectum or via a colostomy.
Barlow’s test a manoeuvre designed to test for congenitally dislocatable hips in the neonate. Often used in association with the Ortolani test. See also developmental dysplasia of the hip.
barn a unit of measure used in atomic physics to measure cross sections which equal 10−28 m2. See also scattered cross-section.
baroreceptors sensory nerve endings which respond to pressure changes. They are present in the cardiac atria, aortic arch, venae cavae, carotid sinus and the internal ear.
Barrett’s oesophagus benign, ulcer-like lesions in columnar epithelium of the lower oesophagus often resulting from chronic irritation by the acid from gastric reflux. Predisposes to oesophageal cancer.
barrier nursing a method of preventing the spread of infection from an infectious individual to other people. It is achieved by isolation techniques.
Bartholin’s glands (greater vestibular glands) two small glands situated at each side of the external orifice of the vagina. Their ducts open into the vestibule. They produce lubricating mucus that facilitates coitus.
bartholinitis inflammation of Bartholin’s (greater vestibular) glands.
Barton’s fracture a break in the distal articular surface of the radius which may be associated with dorsal dislocation of the carpus on the radius.
basal cell carcinoma a tumour of the basal aspect of the epidermis which accounts for 80% of all skin tumours.
basal dose rate used in brachytherapy and is the average of all dose rates calculated at the minimum dose point in the central transverse plane of a brachytherapy dose distribution. Used in the Paris system of dosimetry.
basal ganglia structures in the peripheral nervous system. See also basal nuclei.
basal metabolic rate (BMR) the energy consumed at complete rest for essential physiological functions. It is influenced by nutritional status, age, gender, physiological status, disease, certain drugs and ambient temperature. It is determined by measuring the oxygen consumption when the energy output has been reduced to a basal minimum, that is the person is fasting and is physically and mentally at rest, and is expressed per kilogram body weight. In clinical practice it is usually estimated by prediction equations and used to estimate energy requirements.
basal metabolism the minimum energy expended in the maintenance of essential physiological processes such as respiration.
basal nuclei a collection of interconnected structures (grey cells) deep within the cerebral hemispheres concerned with cognition, and modifying and coordinating voluntary muscle movement. Their proper functioning requires the release of the neurotransmitter dopamine. Sometimes erroneously referred to as ganglia, which more properly describes structures in the peripheral nervous system. Site of degeneration in Parkinson’s disease. See also dopamine.
base the lowest part such as the lung. The major part of a compound. An alkali. A supporting medium for other layers of either a film or intensifying screens. See also blue-based films, clear-based films.
basement membrane a thin layer beneath the epithelium of mucous surfaces.
BASIC (Beginners All-purpose Symbolic Instruction Code) a high level language for computers and almost universally used for home computers.
basic fog the recorded density of a radiographic film base plus the recorded density of chemical blackening on an unexposed part of a film.
basic life support (BLS) a term that describes the application of artificial respiration (usually by mouth-to-mouth breathing) and external cardiac massage to save life without the use of artificial aids or equipment.
basilic vein on the inner side of the arm.
basophil a cell which has an affinity for basic dyes. A polymorphonuclear granulocyte (white blood cell) which takes up a particular dye: it is phagocytic and has granules containing heparin and histamine.
basophilia increase in the number of basophils in the blood. Basophilic staining of red blood cells.
Batchelor plaster a type of double abduction plaster, with the legs encased from groins to ankles, in full abduction and medial rotation. The feet are then attached to a wooden pole or ‘broomstick’. Alternative to frog plaster, but the hips are free. See also developmental dysplasia of the hip.
battery legal term. An unlawful touching. Constitutes a trespass against the person. See also assault.
Battle’s sign bruising over the mastoid process indicative of a skull fracture.
baud the unit for measuring the rate at which data are transmitted or received.
BCG (bacille Calmette–Guörin) an attenuated form of tubercle bacilli: it has lost its power to cause tuberculosis, but retains its antigenic function; it is the base of a vaccine used for immunization against tuberculosis. Also used in urology for the treatment of high-risk superficial bladder cancer.
beam metal pole attached to a hospital bed to facilitate the use of traction. For example, a Thomas’ splint can be slung up, with pulleys and weights attached, to allow movement and provide counterbalance to the weight of the splint and leg.
beam direction device pointers, light sources or laser beams used to indicate the beam direction, the centre of the beam and the source skin distance.
beam direction shell a device worn by the patient to enable accurate and reproducible treatment localization, patient positioning, patient contour, beam exit and entry points and a base for additional build-up material. Produced using either clear Perspex or a thermoplastic material.
beam’s eye view when an observer looks directly at the planning target volume from the position of the central ray from the X-ray tube, this gives the extent of the beam coverage.
beam hardening when the total intensity of the X-ray beam is reduced by the addition of filters, as the reduction is much greater at lower energies. An increase in the average energy of an X-ray spectrum caused by greater absorption of the low-energy component by filtration.
beam hardening filters addition of pieces of metal to improve the relative penetration of the X-ray beam, they are not effective at megavoltages. See also compound filters.
beam intensity modulation linear accelerator beam intensity is varied during treatment by altering the collimation leaves to create a better dose distribution over the field.
beam profile the dose of the X-ray beam including any scattered radiation which is added to the primary beam as it passes through the patient. The variation of dose along a line at right angles to the central axis of a radiation beam.
beam quality is the penetrating ability of primary radiation and is influenced by: the accelerating voltage (kVp) across the tube, the voltage waveform, the target material, the inherent filtration and the additional filtration.
beam width the width of an ultrasound beam at a given depth in the patient.
beat pulsation of the blood in the heart and blood vessels. dropped beat refers to the loss of an occasional ventricular beat as occurs in extrasystoles. premature beat an extrasystole.
Beau’s lines transverse ridges or grooves which reflect a temporary retardation of the normal nail growth following a debilitating illness. They first appear towards the proximal nail fold and move towards the free edge as the nail grows. The distance the groove has moved indicates quite accurately the length of time since the illness or trauma (nail growth being about 1 mm per week).
becquerel (Bq) the derived SI unit (International System of Units) for radioactivity. Equals the amount of a radioactive substance undergoing one nuclear disintegration per second. Has replaced the curie.
bed cradle a frame placed over a patient’s body to relieve the weight of bedding over the injured part of the body.
bed elevator a wedge used to raise either end of a bed, for example, to aid breathing or to treat shock.
bedpan a shallow vessel used for defecation or urination by patients who are confined to bed.
bedsore obsolete term for decubitus ulcer or pressure sore. A breakdown of the skin due to pressure or immobility; usual sites are buttocks, heels, elbows, shoulders.
Beer Lambert Law the greater the distance a ray of light travels in a coloured medium the more it is absorbed.
Behöet syndrome a form of systemic vasculitis. There is stomatitis, genital ulceration and uveitis. There may also be skin nodules, thrombophlebitis and arthritis of one or more of the large joints. Gastrointestinal and neurological complications may occur. The syndrome is associated with the presence of a certain human leukocyte antigen (HLA). Treatment is with non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids and immunosuppressant drugs.
bejel a non-venereal form of syphilis mainly affecting children in the Middle East and sub-Saharan Africa. The causative organism is Treponema pallidum. It usually starts in the mouth and affects mucosae, skin and bones.
Bell’s palsy usually non-permanent facial hemiparesis due to idiopathic (cause unknown) lesion of the seventh (facial) cranial nerve.
Bence Jones protein protein that is excreted in the urine of some patients with multiple myeloma; composed of fragments of immunoglobulin molecules.
benchmarking part of quality assurance. Involves the identification of examples of best practice from others engaged in similar practice. From this, best practice benchmark scores in agreed areas of care are identified, against which individual units can compare their own performance.
bends (caisson disease) results from sudden reduction in atmospheric pressure, as experienced by divers on return to surface, aircrew ascending to great heights. Caused by bubbles of nitrogen which are released from solution in the blood; symptoms vary according to the site of these. The condition is largely preventable by proper and gradual decompression technique. See also decompression illness.
benign benign, simple or innocent tumours are encapsulated, do not infiltrate adjacent tissue and are unlikely to recur if removed. They are non-malignant (of a growth), non-invasive (no capacity to metastasize), non-cancerous (of a growth). Describes a condition or illness which is not serious and does not usually have harmful consequences.
benign hypotonia describes infants who are initially floppy but otherwise healthy. Improvement occurs and the infant regains normal tone and motor development.
benign intracranial hypertension (BIH) a condition in which there is raised intracranial pressure with papilloedema and which can lead to the loss of vision, typically in young, obese women. Often associated with thrombosis in the sagittal sinus.
benign myalgic encephalomyelitis (BME) a flu-like illness with varied symptoms including dizziness, muscle fatigue and spasm, headaches and other neurological pain. A high percentage of BME sufferers have a higher level of coxsackie B antibodies in their blood than the rest of the population.
benign tumour a localized growth which is not malignant and does not metastasize but may be dangerous by virtue of its position.
Bennett’s fracture fracture/dislocation of proximal end of first metacarpal involving the first carpo-metacarpal joint.
benzene a colourless inflammable liquid obtained from coal tar. Extensively used as a solvent. Continued occupational exposure to it results in aplastic anaemia and, rarely, leukaemia.
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