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The unit was named after British physicist Louis Harold Gray, a pioneer in the measurement of X-ray and radium radiation and their effects on living tissue. [ 2 ] The gray was adopted as part of the International System of Units in 1975.
Absorbed dose is a dose quantity which is the measure of the energy deposited in matter by ionizing radiation per unit mass.Absorbed dose is used in the calculation of dose uptake in living tissue in both radiation protection (reduction of harmful effects), and radiology (potential beneficial effects, for example in cancer treatment).
dose area product (DAP) measured in gray centimeters 2; dose length product (DLP) measured in gray centimeters; rads a deprecated unit of absorbed radiation dose, defined as 1 rad = 0.01 Gy = 0.01 J/kg; Roentgen a legacy unit of measurement for the exposure of X-rays; Each measure is often simply described as ‘dose’, which can lead to ...
The commission has been responsible for defining and introducing many of the following units of measure. The number of different units for various quantities is indicative of changes of thinking in world metrology, especially the movement from cgs to SI units. [6] The following table shows radiation quantities in SI and non-SI units.
In diagnostic radiology, the F-factor is the conversion factor between exposure to ionizing radiation and the absorbed dose from that radiation. In other words, it converts between the amount of ionization in air (roentgens or, in SI units, coulombs per kilogram of absorber material) and the absorbed dose in air (rads or grays).
Dose area product (DAP) is a quantity used in assessing the radiation risk from diagnostic X-ray radiography examinations and interventional procedures, like angiography.It is defined as the absorbed dose multiplied by the area irradiated, expressed in gray-centimetres squared (Gy·cm 2 [1] – sometimes the prefixed units dGy·cm 2, mGy·cm 2 or cGy·cm 2 are also used). [2]
gray: Gy: 1 Gy = 1 J/kg: The gray is a special name for joule per kilogram, to be used as the SI unit for absorbed dose. rad: 1 rad = 0.01 Gy dose equivalent: H: Product of D, Q and N, at the point of interest in tissue, where D is the absorbed dose, Q is the quality factor and N is the product of any other modifying factors H = D · Q · N
Unit Symbol Derivation Year SI equivalent Activity (A) becquerel: Bq s −1: 1974 SI unit curie: Ci 3.7 × 10 10 s −1: 1953 3.7 × 10 10 Bq rutherford: Rd 10 6 s −1: 1946 1 000 000 Bq Exposure (X) coulomb per kilogram: C/kg C⋅kg −1 of air 1974 SI unit röntgen: R esu / 0.001 293 g of air 1928 2.58 × 10 −4 C/kg: Absorbed dose (D) gray ...