A Computed Tomography (CT) Organ Dose Library for Pregnant Females of Varying Body Size and Fetuses of Varying Gestational Age
S Domal1*, C Kofler2, L Carter3, J Ocampo Ramos3, A Kesner3, P Zanzonico3, W Bolch1, (1) University of Florida, Gainesville, FL, (2) University of Chicago, Chicago, IL, (3) Memorial Sloan Kettering Cancer Center, New York, NY,
Presentations
SU-K-201-1 (Sunday, 7/10/2022) 5:00 PM - 6:00 PM [Eastern Time (GMT-4)]
Room 201
Purpose: To create a robust precomputed CT organ dose library as applied to a newly developed ninety-member pregnant female phantom library with systematic variation in maternal height, weight, and gestational age. This library will provide both maternal and fetal-organ dose estimates for both fixed and tube-current modulation (TCM) scans across a variety of scan protocols.
Methods: This study utilizes the University of Florida library of pregnant female hybrid computational phantoms, which includes six gestational ages (15, 20, 25, 30, 35, and 38 weeks), three different height percentiles (10th, 50th, and 90th) and five different weight percentiles (10th, 25th, 50th, 75th and 90th). Following our laboratory’s CT dosimetry methodology, individual CT axial slices were simulated on a selection of the 90-phantom library using the Monte Carlo transport code PHITS. Slice-specific organ dose data were then used to calculate doses for specific protocols based on scan range. An in-house algorithm was used to account for the influence of TCM scan protocols.
Results: Preliminary results highlight rapidly achieved organ-level dosimetry estimates for both the mother and fetus for several different scan protocols using our library. Generally, organ absorbed dose decreases in the mother and fetus as maternal weight increases for a given set of CT technique factors. Additionally, maternal organ absorbed dose tend to decrease with increasing fetal age.
Conclusion: This work provides a robust database that can be used to estimate maternal and fetal doses from various CT examinations for a variety of maternal weights and fetal gestational ages. Resulting dose trends highlight the importance of having a wide variety of pregnant female phantoms to enable greater accuracy in CT dosimetry estimates.
Funding Support, Disclosures, and Conflict of Interest: This work was supported by NIH Grant U01 EB028234.
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