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The roentgen or röntgen (/ ˈ r ɛ n t ɡ ə n,-dʒ ə n, ˈ r ʌ n t-/; [2] symbol R) is a legacy unit of measurement for the exposure of X-rays and gamma rays, and is defined as the electric charge freed by such radiation in a specified volume of air divided by the mass of that air (statcoulomb per kilogram).
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]
7 × 10 ^ −1: Acute-Mammogram [7] 1 1 × 10 ^ 0: Annual: 0.11: Limit of dose from man-made sources to a member of the public who is not a radiation worker in the US and Canada [6] [9] 1.1 1.1 × 10 ^ 0: Annual: 0.13: Average USA radiation worker occupational dose in 1980 [6] 1.2 1.2 × 10 ^ 0: Acute-Abdominal X-ray [7] 2 2 × 10 ^ 0: Annual ...
The adoption of the gray by the 15th General Conference on Weights and Measures as the unit of measure of the absorption of ionizing radiation, specific energy absorption, and of kerma in 1975 [17] was the culmination of over half a century of work, both in the understanding of the nature of ionizing radiation and in the creation of coherent ...
The computed tomography dose index (CTDI) is a commonly used radiation exposure index in X-ray computed tomography (CT), first defined in 1981. [1] [2] The unit of CTDI is the gray (Gy) and it can be used in conjunction with patient size to estimate the absorbed dose.
Quantity 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
For comparison, radiation levels inside the United States Capitol are 85 mrem/yr (0.85 mSv/yr), close to the regulatory limit, because of the uranium content of the granite structure. [14] The NRC sets the annual total effective dose of full body radiation, or total body radiation (TBR), allowed for radiation workers 5,000 mrem (5 rem). [15] [16]
The rep has variously been defined as 83 or 93 ergs per gram of tissue (8.3/9.3 mGy) [13] or per cc of tissue. [14] In 1953 the ICRU recommended the rad, equal to 100 erg/g as a new unit of absorbed radiation, [15] but then promoted a switch to the gray in the 1970s.