| Zhang Jian,Yang Feng,Wang Ying,Zhang Xiaojun.Preliminary study on the typical values of diagnostic reference level in children's CT examinations[J].Chinese Journal of Radiological Medicine and Protection,2023,43(1):56-62 |
| Preliminary study on the typical values of diagnostic reference level in children's CT examinations |
| Received:August 02, 2022 |
| DOI：10.3760/cma.j.cn112271-20220802-00312 |
| KeyWords:Children Computed tomography Diagnostic reference level |
| FundProject:江苏省政府留学基金(JS-2018-137);江苏省妇幼保健课题(FYX201816);南京市医学科技发展基金(QRX17169) |
| Author Name | Affiliation | E-mail | | Zhang Jian | Department of Radiology, Children's Hospital of Nanjing Medical University, Nanjing 210000, China | | | Yang Feng | Department of Radiology, Children's Hospital of Nanjing Medical University, Nanjing 210000, China | | | Wang Ying | Department of Radiology, Children's Hospital of Nanjing Medical University, Nanjing 210000, China | | | Zhang Xiaojun | Department of Radiology, Children's Hospital of Nanjing Medical University, Nanjing 210000, China | xjzhang@njmu.edu.cn |
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| Abstract:: |
| Objective To calculate the typical values of diagnostic reference levels (DRLs) for CT examinations of head, chest and abdomen-pelvis in children using the volumetric CT dose index (CTDIvol), the size-specific dose estimation value (SSDEWD) based on the water equivalent diameter (WD) and the dose length product (DLP) as indicators to measure the radiation dose level of CT examinations in Department of Radiology, Children's Hospital of Nanjing Medical University.Methods The CT examination images of patients admitted to the Hospital from January 2021 to December 2021 were retrospectively collected, encompassing 1 391 for head, 1 386 for chest and 1 035 for abdomen-pelvis. Their age, CTDIvol and DLP were recorded and the anterior-posterior diameter (AP), lateral diameter (LAT), area (AROI) and CT value within area (CTROI) of the middlemost scanned image were measured manually. The effective diameter (d), WD, conversion factor (f16/32XSIZE) and SSDEWD were calculated in accordance with the American Academy of Physicists in Medicine (AAPM) reported method. Patients were divided into 5 groups in terms of their examined site. age and body size: <1, 1-, 5-, 10-, and 15-years old. The number of patients in each group was 252, 320, 400, 380 and 39 for the head, 188, 320, 399, 398 and 81 for the chest, and 75, 310, 310, 300 and 40 for the abdomen-pelvis region. The patients for head examination was divided into five groups of <12.5, 12.5-, 14-, 15-, 16-cm based on LAT, with 151, 222, 319, 399 and 300 cases in each group, respectively. The chest and abdomen-pelvis were divided into five groups of <15, 15-, 20-, 25-, 30-cm based on d, with 275, 527, 400, 165 and 19 cases in each chest group, respectively; the abdomen-pelvis 403, 410, 184, 34 and 4 cases. The 75th percentile of CTDIvol, SSDEWDand DLP were counted in each group as typical DRL values, and the differences between CTDIvol and SSDEWD in measuring radiation dose were compared.Results The typical values of DRL in the head, chest and abdomen-pelvis areas as measured by CTDIvol were 14.9-24.1, 1.8-4.5, and 2.0-7.5 mGy, respectively, by age grouping; the typical values of DRL as measured by SSDEWD were 14.7-18.9, 4.2-6.9, and 4.7-11.8 mGy, respectively; the typical values of DRL as measured by DLP were 260-505, 40-185 and 64-435 mGy·cm. The typical values of DRL measured by CTDIvol were 1.8-6.8 and 2.2-9.2 mGy for the chest and abdomen-pelvis region, respectively, by d grouping; the typical values of DRL measured by SSDEWD were 4.2-9.1 and 4.9-13.0 mGy; typical values of DRL as measured by DLP were 40-255 mGy·cm and 85-545 mGy·cm, respectively. The typical values of DRL measured by CTDIvol were 14.1-23.1 mGy for head grouping by LAT; the typical values of DRL measured by SSDEWD were 14.3-18.5 mGy. The typical values of DRL measured by DLP were 240-475 mGy·cm. The CTDIvol was larger than SSDEWD in the head except for the (<1 year and <12.5 cm) subgroup, and the CTDIvol in head was (18.63±3.24) mGy and SSDEWD was (16.38±1.81) mGy, the difference was statistically significant (t= 48.78, P<0.001). The CTDIvol was smaller than SSDEWD within each subgroup in chest and abdomen-pelvis, the CTDIvol of chest was (2.77±1.02) mGy, and SSDEWD was (5.22±1.26) mGy with a statistically significant difference (t=-210.89, P<0.001); the CTDIvol of abdomen-pelvis was (3.36±1.82) mGy and SSDEWD was (6.27±2.44) mGy. The difference was also statistically significant (t=-115.16, P<0.001).Conclusions The typical values of DRLs in the hospital are at a reasonable and low level compared with those in other countries, and SSDEWD reflects radiation dose more accurately than CTDIvol.Therefore there is an urgent need to establish DRLs based on SSDEWD. |
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