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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]
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).
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.
The fundamental quantity is the absorbed dose (D), which is defined as the mean energy imparted [by ionising radiation] (dE) per unit mass (dm) of material (D = dE/dm) [8] The SI unit of absorbed dose is the gray (Gy) defined as one joule per kilogram. Absorbed dose, as a point measurement, is suitable for describing localised (i.e. partial ...
≡ 1 × 10 −18 m: ≡ 1 × 10 −18 m: barleycorn (H) = 1 ⁄ 3 in (see note above about rounding) = 8.4 6 × 10 −3 m bohr, atomic unit of length: a 0 = Bohr radius of hydrogen ≈ 5.291 772 1092 (17) × 10 −11 m [2] cable length (imperial) ≡ 608 ft: ≈ 185.3184 m cable length (International) ≡ 1 ⁄ 10 nmi: ≡ 185.2 m cable length ...
The factor 0.3048 m/ft is identical to the dimensionless 1, so multiplying by this conversion factor changes nothing. Then when adding two quantities of like dimension, but expressed in different units, the appropriate conversion factor, which is essentially the dimensionless 1, is used to convert the quantities to the same unit so that their ...
The rem and millirem are CGS units in widest use among the U.S. public, industry, and government. [4] However, the SI unit the sievert (Sv) is the normal unit outside the United States, and is increasingly encountered within the US in academic, scientific, and engineering environments, and have now virtually replaced the rem. [5]