In-house-developed phantoms for organ dose measurements using bovine tissues: A comparison study with CT-Expo simulation software

Abstract

Background: Estimating organ dose from computed tomography (CT) procedures is still ongoing. The aim is to reduce induced cancer risk associated with over dose. Aim and Objectives: The aim of this study was to estimate organ dose using CT-Expo software, to compare obtained values with thermoluminescent dosimeter (TLD) measurements from validated in-house phantoms, and to compare the CT-Expo results with other related studies. Materials and Methods: Four CT diagnostic centers denoted as A, B, C, and D were randomly selected for this study. A CT-Expo software (version 2.5 Germany) was used. A preliminary study was carried out to determine organ dose from the in-house phantoms using bovine tissues. The CT dose parameters used with the in-house phantoms were retrieved from the CT monitor and were used with CT-Expo worksheet to estimate organ dose as well. Results: The CT-Expo mean organ dose to the brain, eye lens, esophagus, and thyroid were 29.05 ± 10.78, 35.65 ± 15.1, 12.45 ± 10.13, and 4.25 ± 2.78 mGy, respectively; to the heart and lungs were 13.08 ± 9.84 and 11.5 ± 7.26 mGy, respectively; and to the liver, stomach, and kidney were 14.42 ± 9.07, 12.78 ± 7.97, and 11.73 ± 7.92 mGy, respectively. There was no statistically significant difference between the TLD measurements and CT-Expo (P = 0.361). The relative difference between CT-Expo and TLD measurements for brain, eye lens, heart, lungs, kidney, liver, and stomach were ≤21%. Investigated organ doses from the software were between 4.25 and 35.65 mGy. There was no difference in mean organ dose when compared to the studies in Thailand, Tanzania, Japan, USA (cadavers 1 and 2), and Nigeria. Conclusion: Large percentage differences were noticed in the thyroid and esophagus which was as a result of the software not recognizing them as organs in the head/neck but rather as organs in the chest; however, there was no difference in organ dose between the CT-Expo and TLD measurement from the in-house-validated phantom.