Effective Dose Determination Using an Anthropomorphic Phantom and Metal Oxide Semiconductor Field Effect Transistor Technology for Clinical Adult Body Multidetector Array Computed Tomography Protocols


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Abstract

Purpose:To determine the organ doses and total body effective dose (ED) delivered to an anthropomorphic phantom by multidetector array computed tomography (MDCT) when using standard clinical adult body imaging protocols.Materials and Methods:Metal oxide semiconductor field effect transistor (MOSFET) technology was applied during the scanning of a female anthropomorphic phantom to determine 20 organ doses delivered during clinical body computed tomography (CT) imaging protocols. A 16-row MDCT scanner (LightSpeed, General Electric Healthcare, Milwaukee, Wis) was used. Effective dose was calculated as the sum of organ doses multiplied by a weighting factor determinant found in the International Commission on Radiological Protection Publication 60. Volume CT dose index and dose length product (DLP) values were recorded at the same time for the same scan.Results:Effective dose (mSv) for body MDCT imaging protocols were as follows: standard chest CT, 6.80 ± 0.6; pulmonary embolus CT, 13.7 ± 0.4; gated coronary CT angiography, 20.6 ± 0.4; standard abdomen and pelvic CT, 13.3 + 1.0; renal stone CT, 4.51 + 0.45. Effective dose calculated by direct organ measurements in the phantom was 14% to 37% greater than those determined by the DLP method.Conclusions:Effective dose calculated by the DLP method underestimates ED as compared with direct organ measurements for the same CT examination. Organ doses and total body ED are higher than previously reported for MDCT clinical body imaging protocols.

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