Objective: To study whether the actual radiation exposure is different between computed tomography (CT) scanners and medical centers when the same patient is scanned, we investigated the actual effective doses for a whole body (Chest-Pelvis) CT scan in a multicenter study.
Materials and methods: Data from subjects were collected using 12 CT scanners at six medical centers in Yamagata city. Effective-dose data were acquired by scanning the same phantom (ATOM Dosimetry Phantoms Model702-B) using 120 kV tube voltage. Effective doses were calculated using corrected data from a radiophotoluminescent glass dosimeter (GD-302M). GD-302M had energy- dependent issues, which needed to be corrected. Also, differences in sensitivity based on arrangement within the phantom were insignificant.
Results: The mean effective energy was 48.6 keV (range, 42.5-55.4 keV), and the mean effective dose was 16.3 mSv (range, 8.9-26.0 mSv). The mean effective dose with a hybrid type iterative reconstruction was 10.7 mSv (range, 8.9-16.4 mSv), but the mean effective dose without any iterative reconstruction was 20.3 mSv (range, 16.2-26.0 mSv). We found an approximate linear correlation between dose length product (DLP) on operation consoles and the effective dose.
Conclusion: We suggest that the actual radiation exposure was different at each medical center when the same patient is scanned.
Keywords: dose length product (DLP); effective dose; effective energy; radiophotoluminescent glass dosimeter; volume computed tomography dose index (CTDIvol).