| Han Jiaxing,Niu Yantao,Sun Baohua.Correction of CT radiation dose index and study on fast conversion factor[J].Chinese Journal of Radiological Medicine and Protection,2022,42(5):391-395 |
| Correction of CT radiation dose index and study on fast conversion factor |
| Received:December 24, 2021 |
| DOI：10.3760/cma.j.cn112271-20211224-00495 |
| KeyWords:CTDIvol Size specific dose estimates Effective diameter Water equivalent diameter |
| FundProject:北航-首医大数据精准医疗高精尖创新中心同仁分中心开放基金项目(BHTR-KFJJ-202007) |
| Author Name | Affiliation | E-mail | | Han Jiaxing | School of Physics, Beihang University, Beijing 100191, China | | | Niu Yantao | Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China | ytniu163@163.com | | Sun Baohua | School of Physics, Beihang University, Beijing 100191, China | |
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| Abstract:: |
| Objective To explore the influence of different size related parameters of common CT scanned body parts on body-specific dose estimate (SSDE), in order to establish rapid conversion factors for SSDE.Methods A total of 189 clinical cases were collected from 6 common CT scanned body parts, including head, nasal bone, sinus, neck, chest, abdomen and pelvis, at Beijing Tongren Hospital, Capital Medical University from March 8 to May 10, 2021. Batch-processing of image was carried out by using Matlabcode. The axial images'area, anteroposterior (AP) dimension, lateral (LAT) dimension and average CT values were calculated. The conversion factors for estimating body-specific dose values were obtained from the real effective diameter (De) and water equivalent diameter (Dw) of the clinical cases, and the differences in values were compared between SSDEED and SSDEWED. Based on the information on AP, LAT, AP + LAT, estimatedDe, the realDe andDw obtained in clinical practices, the SSDE rapid correction factors for adult body parts were established. The convenient conversion relation betweenDw andDe was obtained. Based on the correction factors forDw, the relative errors of the correction factors for various sizes related parameters were compared.Results The SSDE fast conversion factors for the realDe of the 6 body parts were 1.01, 1.01, 1.01, 0.97, 1.28, 1.32, and those forDw were 0.87, 0.97, 0.98, 0.99, 1.42, 1.36, respectively. The relative errors of different conversion factors ranged from 0.68% to 18.05%. The conversion factors for abdomen and pelvis had the smallest difference, and those for AP and LAT of the chest had the smallest error. The differences between CTDIvol, SSDEED and SSDEWED in sinus, chest and abdomen were statistically significant (tsinus=2.44, 4.23,tchest=17.67,17.00,tabdomen and pelvis =17.93, 18.75,P<0.05). The differences between CTDIvol and SSDEWED in head, nasal bone, were statistically significant (t=-22.27, 2.80,P<0.05), but not with SSDEED (P>0.05). The difference between CTDIvol and SSDEED in neck was statistically significant (t=-3.06,P<0.05) but without statistical insignificance in camparison with SSDEWED (P>0.05).Conclusions SSDEWED can be used to accurately evaluate the body-specific dose estimatates, and different size related parameters can be selected for correction in different scanned body parts. The rapid conversion factor can be easily used in clinical practice to improve the accuracy of estimated radiation dose. |
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