验证 iCT 256执行头部轴扫时辐射剂量机显值准确性，并探讨在该条件下辐射剂量安全管理方案。方法利用瑞典 RTI 公司的 Solidose 400型辐射剂量计和中国计量科学研究院研制的T6M164型剂量体模（符合 IEC 61223-2-6），按头部轴扫条件重复三次测定剂量体模上5个钟点位的剂量值。结果①中心点 CTDI100测量相对偏差在2％以内，而四周点位 CTDI100测量相对偏差在20％以内；②CTDIvol实测值比机显值高5％～16％；③单次头部轴扫有效剂量在0.86～3.63 mGy 之间。结论中心点 CTDI100的测量重复性好，外围四点位测量重复性差，且存在实测值略高于机显值的情况。应加强对患者累计辐射剂量的监管。%Objective To verify the reported CTDIvol value and explore dose safety managementprotocol of Philips Brilliance iCT 256 under axial scan mode with head protocolMethods A pencil dosimeter,Solidose 400 from Sweden RTI Electronics,is utilized to detect radiation dose index of phantom T6M1 64 (incompliance with IEC standard 61 223-2-6,provided by National Institute of Metrology of China)when scannedby iCT 256 under head axial protocolResults (1)Relative deviation of CTDI1 00 in the center point is about 2%and those in the peripheral 4 points are about 20% (2)Tested CTDIvol value is 5% ~1 6% greater thanreported value(3) Effective absorbing dose during one head axial scanning is about 086 mGy to 363mGyConclusions Accuracy of CTDI1 00 measurement in the center point is better than the peripheral fourpointsTested CTDIvol value might be greater than reported CTDIvol in certain conditions and supervision onaccumulated radiation dose of patient should be recommended.
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