Technical developments are ongoing in CT, and there has been a continually\nincreasing trend in patient prescription, resulting in increased exposure.\nCurrently, doses delivered during CT are generally evaluated using computed\ntomography dose index (CTDI), which is measured with a 10 cm pencil ionization\nchamber placed in a 14 cm PMMA phantom. However, shortfalls in\nCTDI have been identified by the American Association of Physicists in\nMedicine (AAPM) who have proposed a new method, dose equilibrium\n(DEq). In this paper, the dose equilibrium was used to estimate the dose in\ntwo protocols (thoracic and abdominopelvic) and compared to CTDI values.\nIn addition, a retrospective correction was applied to 20 patient CTDIâ??s by\ncharacterizing the specific DEq profile of the system scans. The results indicated\nthe dose equilibrium estimations of two protocols, thoracic and abdominopelvic,\nwere 29% and 30% respectively, higher than those informed by\nthe CT scanner. In addition, a retrospective dose correction estimation of a\nrandom sample of twenty patients demonstrated an annual underestimation\nin absorbed dose by between 26% and 28%. Continued use of the CTDI method\nin quality assurance of modern CT could result in greater patient risk.\nAAPM Task Group 111 presents a more accurate, safer method to estimate\ndose and its adoption is paramount.
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