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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).
1 000 000 000 000 000 000 000 000: 10 24: zetta Z 1 000 000 000 000 000 000 000: 10 21: exa E 1 000 000 000 000 000 000: 10 18: peta P 1 000 000 000 000 000: 10 15: tera T 1 000 000 000 000: 10 12: giga G 1 000 000 000: 10 9: mega M 1 000 000: 10 6: kilo k 1 000: 10 3: hecto h 100 10 2: deca da 10 10 1 (none) (none) 1 10 0: deci d 0.1 10 −1 ...
newton meter squared per kilogram squared (N⋅m 2 /kg 2) shear modulus: pascal (Pa) or newton per square meter (N/m 2) gluon field strength tensor: inverse length squared (1/m 2) acceleration due to gravity: meters per second squared (m/s 2), or equivalently, newtons per kilogram (N/kg) magnetic field strength
The stokes (St) is a unit of kinematic viscosity equal to 1 cm 2 ⋅s −1 (100 mm 2 ⋅s −1). [3] The stilb (sb) is a unit of luminance equal to 1 cd⋅cm −2 (10 kcd⋅m −2). [4] The phot (ph) is a unit of illuminance equal to 1 lm⋅cm −2 (10 klx). [3] The rayl is a unit of specific acoustic impedance, equal to 1 dyn⋅s⋅cm −3 (10 ...
A barn (symbol: b) is a metric unit of area equal to 10 −28 m 2 (100 fm 2).This is equivalent to a square that is 10 −14 m (10 fm) each side, or a circle of diameter approximately 1.128 × 10 −14 m (11.28 fm).
The two forms have different dimensions and units: spectral irradiance of a frequency spectrum is measured in watts per square metre per hertz (W⋅m −2 ⋅Hz −1), while spectral irradiance of a wavelength spectrum is measured in watts per square metre per metre (W⋅m −3), or more commonly watts per square metre per nanometre (W⋅m −2 ...
The quality of a beam is important for many applications. In fiber-optic communications beams with an M 2 close to 1 are required for coupling to single-mode optical fiber. M 2 determines how tightly a collimated beam of a given diameter can be focused: the diameter of the focal spot varies as M 2, and the irradiance scales as 1/M 4.