Objective This study aimed to investigate the strength of the correlation between organ doses and four CT dose metrics, and to explore a method for rapidly estimating organ doses in patients undergoing chest-abdominal-pelvic (CAP) CT examinations. Methods We retrospectively collected DICOM images of 43 patients who underwent CAP CT examinations. These images were imported into Archer-CT for organ segmentation and dose calculation. Then, regarding the six radiosensitive organs (spinal cord, lung, esophagus, stomach, liver, and bladder) that were included in the study, various radiation dose metrics were calculated based on size-specific dose estimate (SSDE) derived from equivalent water diameters (Dw), i.e. SSDEcenter based on Dw in the center of the scan range, the SSDEmean based on the mean SSDEs of all slices, and the organ-specific SSDEorgan for various organs, as prescribed in AAPM Report 220. Subsequently, correlation analyses were applied to evaluate the relationship between the organ doses and each radiation dose metric and to derive conversion factors for rapid estimating organ doses. Results The ranked linear correlations of the four dose metrics with each organ dose were as follows, in descending order: SSDEorgan, SSDEmean, CTDIvol, and SSDEcenter. The strongest correlation was found between organ dose to liver and SSDELiver (R² = 0.88). The weakest correlation was found between organ dose to the bladder and SSDEBladder (R² = 0.62), and the R² of the rest of the organ doses to SSDEorgan was around 0.8. The conversion coefficients for estimating organ doses based on SSDEorgan for the spinal cord, lung, esophagus, liver, stomach, and bladder were 0.75, 1.24, 0.89, 1.17, 1.18, and 0.83, respectively. Conclusions Higher correlation were observed between organ doses and SSDEorgan for organs involved in this study during CAP CT examinations. Thus, SSDEorgan can be used to simplify and estimate the individualized organ dose for CAP CT examinations.
liang et al. (Fri,) studied this question.