Haji-Momenian S, et al. - A comparative scrutiny was conducted of the dose-length product (DLP)–based calculation of effective dose (ED^DLP) with Monte Carlo simulation organ-based calculation of effective dose (ED^MCO) in 16- and 64-MDCT examinations, via clinical examinations with automatic tube current modulation. In unenhanced head CT examinations and, among women, in chest CT examinations, ED^DLP underestimated ED^MCO, the reference standard for dose calculation, by 19-39%. It was determined that ED^DLP appeared to deviate from ED^MCO by less than 15% in the case of chest CT examinations of men and for abdominopelvic CT. Such variations could arise due to variable patient body habitus, automatic tube current modulation, and sex-neutral κ-coefficients, which ought to be taken into account while estimating ED, especially in women.