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The average radiation dose from an abdominal X-ray is 0.7 millisieverts (0.0007 Sv), that from an abdominal CT scan is 8 mSv, that from a pelvic CT scan is 6 mGy, and that from a selective CT scan of the abdomen and the pelvis is 14 mGy. [7]
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]
Human internal radiation due to radon, varies with radon levels [8] 2 2 × 10 ^ 0: Acute-Head CT [7] 3 3 × 10 ^ 0: Annual: 0.34: USA average dose from all natural sources [6] 3.66 3.66 × 10 ^ 0: Annual: 0.42: USA average from all sources, including medical diagnostic radiation doses [citation needed] 4 4 × 10 ^ 0: Duration of the pregnancy: 0.6
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.
The sievert (symbol: Sv [note 1]) is a unit in the International System of Units (SI) intended to represent the stochastic health risk of ionizing radiation, which is defined as the probability of causing radiation-induced cancer and genetic damage.
It may be used to estimate stochastic risk provided the amount and type of tissue involved is stated. Localised diagnostic dose levels are typically in the 0–50 mGy range. At a dose of 1 milligray (mGy) of photon radiation, each cell nucleus is crossed by an average of 1 liberated electron track. [9]
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]
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).