| 韩加星,牛延涛,孙保华.CT辐射剂量指数的修正和快速转换因子的探讨[J].中华放射医学与防护杂志,2022,42(5):391-395 |
| CT辐射剂量指数的修正和快速转换因子的探讨 |
| Correction of CT radiation dose index and study on fast conversion factor |
| 投稿时间：2021-12-24 |
| DOI：10.3760/cma.j.cn112271-20211224-00495 |
| 中文关键词: 容积CT剂量指数 体型特异性剂量估计 有效直径 水当量直径 |
| 英文关键词:CTDIvol Size specific dose estimates Effective diameter Water equivalent diameter |
| 基金项目: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) |
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| 中文摘要: |
| 目的 探讨临床常见CT扫描部位中不同尺寸参量对体型特异性剂量估算(SSDE)的影响,以建立SSDE的快速转换因子。方法 于2021年3月8日至5月10日在首都医科大学附属北京同仁医院收集颅脑、鼻骨、鼻窦、颈部、胸和腹盆6个临床常见扫描部位共189个临床病例。利用Matlab自编程序进行批量图像处理,计算横断面图像的面积、前后径、左右径以及平均CT值信息,由病例的真实有效直径和水当量直径得到估算体型特异性剂量值的转换因子,并比较两种特异性剂量估计(SSDEED和SSDEWED)值的差异。根据临床实践中便于得到的前后径、左右径、前后径+左右径、估算有效直径,以及程序所得真实有效直径和水等效直径,建立便于应用的成年人各部位SSDE快速修正因子。得出水当量直径和有效直径的便捷转换关系。以水当量直径对应的修正因子为基准,比较各种尺寸参量对应的修正因子之间的相对误差。结果 颅脑、鼻骨、鼻窦、颈部、胸部和腹盆6个CT检查部位的真实有效直径对应的SSDE快速转换因子分别为1.01、1.01、1.01、0.97、1.28、1.32,水当量直径对应的SSDE快速转换因子分别为0.87、0.97、0.98、0.99、1.42、1.36。不同类型转换因子之间相对误差变化范围为0.68%~18.05%。腹盆部的各种尺寸参量的转换系数相差最小,胸部的前后径和左右径对应的转换系数误差最小。颅脑使用左右径对应的转换系数误差最小。鼻窦、胸部和腹盆的CTDIvol与SSDEED和SSDEWED比较,差异均有统计学意义(t鼻窦=2.44、4.23,t胸部=17.67、17.00,t腹盆=17.93、18.75,P<0.05);颅脑和鼻骨的CTDIvol与和SSDEWED比较差异有统计学意义(t=-22.27、2.80,P<0.05),与SSDEED比较差异无统计意义(P>0.05);而颈部CTDIvol与SSDEED比较差异有统计学意义(t=-3.06、P<0.05),与SSDEWED比较差异无统计意义(P>0.05)。结论 SSDEWED可以更加精准的评估受检者的体型特异性剂量,不同扫描部位可选择不同的尺寸参数进行修正。快速转换因子可便捷用于临床操作,提高受检者辐射剂量估计的准确性。 |
| 英文摘要: |
| 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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