Monitoring Dose–length Product in Computed Tomography of the Chest Considering Sex and Body Weight

Abstract

Dose-length product (DLP) is widely used as an indicator of the radiation dose in computed tomography. The aim of this study was to investigate the significance of sex and body weight in DLP-based monitoring of the radiation dose. Eight hundred computed tomographies of the chest performed using four different scanners were analysed. The DLP was compared with body weight by linear regression in men and women separately. The DLP was positively correlated with body weight, and dependence on sex and weight differed among scanners. Standard DLP values adjusted for sex and weight facilitated interscanner comparison of the radiation dose and its dependence on sex and weight. Adjusting the DLP for sex and weight allowed one to identify examinations with possibly excessive doses independently of weight. Monitoring the DLP in relation to sex and body weight appears to aid detailed comparison of the radiation dose among imaging protocols and scanners and daily observations to find unexpected variance.

Factors affecting dose-length product of computed tomography component in whole-body positron emission tomography/computed tomography

“…Weight showed an excellent positive correlation with DLP, and was indicated to be more suitable for radiation dose monitoring than height, BMI and BSA. In a previous study on chest CT, the correlation coefficients between DLP and weight ranged from 0.762 to 0.895 for four CT scanners from three vendors (Inoue et al 2016), while the correlation coefficient in this study was much higher (0.985). This difference Values are mean ± standard deviation.…”

“…When strong attenuation is expected, the AEC increases the tube current and, consequently, radiation exposure, to prevent excessive increase in image noise. As a result, a higher radiation dose is delivered to larger patients than to smaller patients, and positive correlations between patients' weight and CT dose have been reported (Israel et al 2010, Iball and Tout 2014, Inoue et al 2016. The AEC also manipulates radiation exposure along the slice location in an imaging series.…”

Radiation Dose Management in Computed Tomography: Introduction to the Practice at a Single Facility

“…When using AEC, DLP varies with body size and correlates well with body weight [ 20 , 21 , 22 ]. Because a higher DLP in a larger patient does not imply an excessive radiation dose beyond that required, body size should be considered in radiation dose management.…”

“…We determine median doses for standard-sized patients and compare them to the Japanese DRLs [ 23 ] every year and early after changing parameters. However, the relationship between body size and dose varies with the CT scanner and imaging protocol [ 20 , 21 ], and it is desirable to evaluate doses for various body sizes. DRLs for different body sizes have been reported [ 24 ].…”

“…We analyze the radiation dose for each imaging protocol and each CT scanner to determine the standard dose according to body weight [ 20 ]. Total DLP is plotted against weight using our clinical data, and a linear regression equation is determined and used to estimate the standard DLP according to weight ( Figure 1 ).…”