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Korean J Radiol. 2018 Nov-Dec;19(6):1179-1186. doi: 10.3348/kjr.2018.19.6.1179. Epub 2018 Oct 18.

Size-Specific Dose Estimation In the Korean Lung Cancer Screening Project: Does a 32-cm Diameter Phantom Represent a Standard-Sized Patient in Korean Population?

Author information

Department of Radiology, Gachon University Gil Medical Center, Incheon 21565, Korea.
Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea.
Department of Radiology, Seoul National University College of Medicine, Seoul 03080, Korea.
Department of Diagnostic Radiology, National Cancer Center, Goyang 10408, Korea.
Department of Radiology, Pusan National University School of Medicine and Medical Research Institute, Pusan National University Hospital, Busan 49241, Korea.
Department of Radiology, Chungbuk National University Hospital, Cheongju 28644, Korea.
Cancer Early Detection Branch, National Cancer Control Institute, National Cancer Center, Goyang 10408, Korea.



The purposes of this study were to evaluate size-specific dose estimate (SSDE) of low-dose CT (LDCT) in the Korean Lung Cancer Screening (K-LUCAS) project and to determine whether CT protocols from Western countries are appropriate for lung cancer screening in Korea.

Materials and Methods:

For participants (n = 256, four institutions) of K-LUCAS pilot study, volume CT dose index (CTDIvol) using a 32-cm diameter reference phantom was compared with SSDE, which was recalculated from CTDIvol using size-dependent conversion factor (f-size) based on the body size, as described in the American Association of Physicists in Medicine Report 204. This comparison was subsequently assessed by body mass index (BMI) levels (underweight/normal vs. overweight/obese), and automatic exposure control (AEC) adaptation (yes/no).


Size-specific dose estimate was higher than CTDIvol (2.22 ± 0.75 mGy vs. 1.67 ± 0.60 mGy, p < 0.001), since the f-size was larger than 1.0 for all participants. The ratio of SSDE to CTDIvol was higher in lower BMI groups; 1.26, 1.37, 1.43, and 1.53 in the obese (n = 103), overweight (n = 70), normal (n = 75), and underweight (n = 4), respectively. The ratio of SSDE to CTDIvol was greater in standard-sized participants than in large-sized participants independent of AEC adaptation; with AEC, SSDE/CTDIvol in large- vs. standard-sized participants: 1.30 ± 0.08 vs. 1.44 ± 0.08 (p < 0.001) and without AEC, 1.32 ± 0.08 vs. 1.42 ± 0.06 (p < 0.001).


Volume CT dose index based on a reference phantom underestimates radiation exposure of LDCT in standard-sized Korean participants. The optimal radiation dose limit needs to be verified for standard-sized Korean participants.


Early detection; Low-dose CT; Radiation dosage; Radiation dose

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