Radiation Unit: From 1 Different Sources
Several different internationally agreed units (called units) are used to measure ionizing radiation. For example, the roentgen (R) measures the amount of radiation in the air, and the becquerel is the unit of spontaneous activity of a radioactive source such as uranium. For medical purposes, the most commonly used units are the gray (Gy) and the sievert (Sv).
The gray is the unit of radiation that is actually absorbed by any tissue or substance as a result of exposure to radiation. 1 Gy is the absorption of 1 joule of energy (from gamma radiation or X-rays) per kilogram of irradiated matter. The gray supersedes an older unit called the rad (1 Gy = 100 rads).
Because some types of radiation affect biological organisms more than others, the sievert is used as a measure of the impact of an absorbed dose. It uses additional factors, such as the kind of radiation and its energy, to quantify the effects on the body of equivalent amounts of different types of absorbed energy. The sievert replaces an older unit, the rem (1 Sv=100 rems).
The term applied to the nausea, vomiting and loss of appetite which may follow exposure to RADIATION – for example, at work – or the use of RADIOTHERAPY in the treatment of cancer and other diseases. People exposed to radiation at work should have that exposure carefully monitored so it does not exceed safety limits. Doses of radiation given during radiotherapy treatment are carefully measured: even so, patients may suffer side-effects. The phenothiazine group of tranquillisers, such as CHLORPROMAZINE, as well as the ANTIHISTAMINE DRUGS, are of value in the prevention and treatment of radiation sickness.... radiation sickness
A hospital unit equipped and sta?ed to nurse patients who require a high level of technically supported care. Patients are usually moved to such units when they have made satisfactory progress in an INTENSIVE THERAPY UNIT (ITU) and do not require the one-to-one nursing necessary in ITUs. Patients who have undergone major surgery are often transferred from the recovery ward to a high dependency unit until they are well enough to be cared for in a standard ward.... high dependency unit
The band of electromagnetic radiation which has a longer wavelength than that of the red in the visible spectrum. Infrared radiation is used in the special photographic process essential to THERMOGRAPHY. Its property of transmitting radiant heat has made infrared radiation invaluable in PHYSIOTHERAPY, where it warms tissues, soothes pain and increases the local circulation.... infrared radiation
The international system of measurement-units used throughout the sciences. SI units, which derive from metres, kilograms, and seconds, comprise seven basic units and two supplementary ones. Among the other base units are ampere (electric current) and mole (amount of a substance at molecular level). Derived SI units include joule (energy), pascal (pressure), becquerel (activity), and newton (force). (See APPENDIX 6: MEASUREMENTS IN MEDICINE.)... si units
A specialist ward for the care of acutely ill patients who may be suffering, or who have suffered, a myocardial infarction (heart attack) or another serious cardiovascular disorder.... coronary care unit
Called after the Swedish physicist, this is a measurement of length and equals 1/10,000 of a micrometre, or one-hundred-millionth of a centimetre. It is represented by the symbol Å and is used to give the length of electromagnetic waves.... ångström unit
An o?cially recognised measurement of heat: a unit is equal to the quantity of heat needed to raise the temperature of one pound of water by 1°Fahrenheit. One BTU is equivalent to 1,055 joules (see JOULE).... british thermal unit (btu)
A specialised hospital unit equipped and sta?ed to provide intensive care (see INTENSIVE THERAPY UNIT (ITU)) for patients who have had severe heart attacks or undergone surgery on the heart.... coronary care unit (ccu)
Sometimes called an intensive care unit, this is a hospital unit in which seriously ill patients undergo resuscitation, monitoring and treatment. The units are sta?ed by doctors and nurses trained in INTENSIVE CARE MEDICINE, and patients receive 24-hour, one-to-one care with continuous monitoring of their condition with highly specialised electronic equipment that assesses vital body functions such as heart rate, respiration, blood pressure, temperature and blood chemistry. The average ITU in Britain has four to six beds, although units in larger hospitals, especially those dealing with tertiary-care referrals – for example, neurosurgical or organ transplant cases – are bigger, but 15 beds is usually the maximum. Annual throughput of patients ranges from fewer than 200 to more than 1,500 patients a year. As well as general ITUs, specialty units are provided for neonatal, paediatric, cardiothoracic and neurological patients in regional centres. The UK has 1–2 per cent of its hospital beds allocated to intensive care, a ?gure far below the average of 20 per cent provided in the United States. Thus patients undergoing intensive care in the UK are usually more seriously ill than those in the US. This is re?ected in the shortage of available ITU beds in Britain, especially in the winter. (See CORONARY CARE UNIT (CCU); HIGH DEPENDENCY UNIT.)... intensive therapy unit (itu)
A long-term care facility unit with services specifically for persons with particular diseases, disorders or injuries.... special care unit
lx.... the unit of illumination. the abbreviation is
The term applied to a quantity assumed as a standard for measurement. Thus, the unit of insulin is the speci?c activity contained in such an amount of the standard preparation as the Medical Research Council may from time to time indicate as the quantity exactly equivalent to the unit accepted for international use. The standard preparation consists of pure, dry, crystalline insulin. (See APPENDIX 6: MEASUREMENTS IN MEDICINE.)... unit
The unit to which a performance measure is applied (e.g. subjects, patients, clinicians, group of professionals).... unit (of analysis)
(American) Woman who upholds oneness; togetherness Unitey, Unitie, Uniti, Unitee, Unitea, Unyty, Unytey, Unytie, Unyti, Unytee, Unytea, Unite, Unita, Unyta... unity
a unit of heat equal to the quantity of heat required to raise the temperature of 1 pound of water by 1° Fahrenheit. 1 British thermal unit = 1055 joules. Abbrev.: Btu.... british thermal unit
a major fixed piece of dental equipment to which are attached the dental drills, aspirator, compressed air syringe, and ultrasonic scaler. It is frequently integral with the *dental chair.... dental unit
the numerical unit assigned electronically to each *pixel in a computerized tomography (CT) image, according to its X-ray density. The fixed points on the scale are arbitrarily assigned as ?1000 for air and 0 for water. The CT image is viewed in a ‘window’. The range of Hounsfield units displayed (window width) and the centre point of the range of interest (window level) can be varied by the radiologist in order to observe specific tissues (see windowing). The unit was named after Sir Godfrey Hounsfield (1919–2004), who developed CT scanning in the 1950s. Symbol: HU.... hounsfield unit
(ITU, intensive care unit) a hospital unit designed to give intensive care, provided by specialist multidisciplinary staff, to a selected group of seriously ill patients or to those in need of special postoperative techniques (e.g. those patients undergoing complex heart or lung procedures).... intensive therapy unit
see PICU.... psychiatric intensive care unit
measures designed to limit the dose of harmful radiation to patients and workers. Medical exposure to radiation is governed in the UK by the Department of Health and Social Care under the Ionising Radiation (Medical Exposures) Regulations 2000 (IRMER). A guiding theme of protection is the ALARA principle (“as low as reasonably achievable”).... radiation protection
see radioembolization.... selective internal radiation therapy
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