Becquerel, SI unit

Background Radiation amount of natural radiation detected in the absence of nonnatural radioactive sources Base a substance that yields hydroxide ions in solution or accepts protons Becquerel SI unit for activity equal to one disintegration per second, abbreviated Bq... 

SI Units—The International System of Units as defined by the General Conference of Weights and Measures in 1960. These units are generally based on the meter/kilogram/second units, with special quantities for radiation including the becquerel, gray, and sievert. 

The SI unit of activity is the becquerel (Bq) 1 Bq = that quantity of radioactive material in which there is 1 transformation/second. Since activity is proportional to the number of atoms of the radioactive material, the quantity of any radioactive material is usually expressed in curies, regardless of its purity or concentration. The transformation of radioactive nuclei is a random process, and the number of transformations is directly proportional to the number of radioactive atoms present. For any pure radioactive substance, the rate of decay is usually described by its radiological half-life, TR, i.e., the time it... 

The ICRU (1980), ICRP (1984), and NCRP (1985) now recommend that the rad, roentgen, curie, and rem be replaced by the SI units gray (Gy), Coulomb per kilogram (C/kg), Becquerel (Bq), and sievert (Sv), respectively. The relationship between the customary units and the international system of units (SI) for radiological quantities is shown in Table D-5. 

The System Internationale (SI) unit for radioactivity is becquerel (Bq), which is defined as one disintegration per second. The SI units and the conversion factors between curie and SI units are listed in Table 15.2. 

Radiopharmaceuticals are prescribed according to units of radioactivity. A pharmacist practicing nuclear pharmacy may need to convert radio activity units from curies to SI unit, becquerel and its multiples, and vice versa. The following examples illustrate the interconversion of radioactive units. 

The curie unit (Ci) is based on the activity of 1 g of pure radium-226, which undergoes 3.7 X 1010 transformations per second. It is therefore defined as the quantity of a radioactive isotope which gives 3.7 X 1010 disintegrations per second. The SI unit of activity is the becquerel (Bq), which is equal to one nuclear transformation per second. Hence ... 

The SI unit of measure for radioactivity. One becquerel (Bq) is equal to one disintegration per second (dps), thereby corresponding to about 2.703 x 10 curie. 

The conventional unit of radioactivity, the curie (Ci), is equivalait to 3.7 X 10 radioactive events per second. The SI unit used for denoting the amount of radioactive material contained in a given sample of matter is the becquerel (Bq) one becquerel is that quantity of a radioactive nuclide in which there is one radioactive event per second (1 Bq = 2.7 x 10 Ci). Since radionuclides decay exponentially with time, each element at its own rate, the time required for a given quantity of a radionuclide to lose one-half of its radioactivity is call its physical half-Ufe. 

The becquerel (Bq) is the SI unit for measuring the number of nuclear disintegrations occurring per second in a sample 1 Bq = 1 disintegration/s. The curie (Ci) and millicurie (mCi) also measure disintegrations per unit time, but... 

Decay rate is way to quantify radioactive decay and is equal to the number of radioactive decays or disintegrations occurring per unit time. The official SI unit of decay rate is the becquerel (Bq) defined to be ... 

Natural radionuclides contaminate air, food, and water. The annual per capita intake of natural radionuclides has been estimated to range from 2 Becquerels (Bq) for 232Th to about 130 Bq for 4 K (Sinclair 1988). The Bq is the International System of Units (SI) unit of radioactivity 1 Bq = 1 radioactive disintegration per second. The previously used unit of radioactivity is the Curie (Ci) 1 Ci = 3.7 x 1010 disintegrations per second, and 1 Bq = 27 x 10-12 Ci. The quantity of radiation or energy absorbed is expressed in Sievert (Sv), which is the SI unit of dose equivalent. The absorbed dose (in Gy) is multiplied by a quality factor for the particular type of radiation. Rem is the previously used unit for dose equivalent 100 rem = 1 Sv. 

During radioactive decay an unstable atomic nucleus emits radiation in the form of particular particles or electromagnetic waves. This process results in a parallel loss of energy as so-called parent nuclide(s) transform into daughter nuclide(s). The principal types of radioactive decay are alpha (a), beta (ft) and gamma (y), as described further in Table 10.1 the SI unit of radioactive decay is the Becquerel (Bq), where one Bq is one decay (or transformation disintegration) per second. 

In order to understand the effects of radiation on any material, let us define how one measures radiation. Radiation is measured in several units. The SI unit for radioactivity is the becquerel (Bq), which is defined as one disintegration (d) per second (s) (Bq = d/s). However, the most common unit is the curie (Ci) and its definition is based on the number of radium-226 isotopes present in 1 gram of the element that disintegrate in one second. One Ci is thus exactly equal to 3.70 x 1010 disintegrations per second... 

Radioactivity is measured in decays per second, the SI unit of which is the Becquerel (Bq) which is defined as one decay per second. The Curie (Ci), which originally corresponded to the number of decays per second in 1 g of radium, is still used and is now related to the Becquerel by the definition ... 

N. The SI unit of activity is the Becquerel (Bq), which represents one disintegration per second. The disintegration per minute or dpm often appears in the literature. An older representation was the Curie (Ci), which is defined as the activity of 1 g of pure Ra or 3.70 X 10 disintegrations per second. The picocurie (pCi), which is... 

The fundamental SI unit of activity is the Becquerel (Bq). One Bq is equal to one disintegration per second (dps). Because this is a very small unit, it is more often expressed in kilobequerels or kBq. However, the older historical unit of activity Q is normally used for radiopharmaceuticals. The Curie was defined in terms of the number of disintegrations per second of 1 g of Ra and is equal to 3.7 x 10 ° dps. Other commonly used imits are millicurie and microcurie (mCi and pCi). The unit of Ci represents absolute activity (A). However, relative activity R is proportional to the efficiency of the counting device. The device reports in counts per minute. 

One nuclear disintegration per second is called I becquerel, Bq (SI unit). 

The hecquerel (Bq) is the SI unit of radioactivity and is defined as one decay per second (dps). Because 1 Bq is a very small amount of activity, the activity of typical chemistry samples is often expressed in kilobecquerels (kBq). The curie (Ci) is the older, conventional unit it is defined as 3.7 X 10 dps. One curie equals 37 gigabecquerels (GBq). Because the becquerel is inconveniently small and the curie very large, they are typically used as their multiples or submultiples, for example, megabecquerels (MBq) and miUicuries (mCi). One mCi equals 37 MBq. 

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