仿真儿童体模头部CT检查剂量及屏蔽防护效果研究

Head doses and effects of shielding for head CT scan of children phantom model

目的本研究通过利用仿真儿童人体模型实验来研究儿童头颅CT扫描的各器官和组织的吸收剂量和有效剂量,探讨采取屏蔽防护措施降低剂量的效果。方法使用GE HD750型CT进行儿童头颅CT扫描,在1岁、10岁两种儿童仿真体模内布放热释光剂量计,获得在非投照部位未防护及采用0.5 mmPb的铅橡胶方巾包裹屏蔽两种条件下儿童组织和器官的吸收剂量,并计算有效剂量,讨论采取铅橡胶方巾包裹屏蔽在儿童头颅CT检查中对辐射的屏蔽效果。结果 1岁儿童体模实验防护组较未防护组的甲状腺、肺、胃、肠和乳腺等敏感组织器官的吸收剂量降低40.4%以上,有效剂量由4.9 mSv降低至2.2 mSv,降低了55.7%;10岁儿童体模敏感器官的吸收剂量降低了39.5%以上,有效剂量由2.4 mSv降低至1.7 mSv,降低了30.5%。结论采用铅橡胶方巾包裹防护可以明显降低各器官或组织的吸收剂量和有效剂量。

Objective This study showed the effective dose and the absorbed doses of organs and tissues,and discussed the effects of shielding for head CT scan by using children phantom model.Methods This study simulated children head CT scan under clinical condition with Discovery CT 750 HD by setting the thermoluminescent dosimeters in one-year old and ten-year old phantom,gained the absorbed dose of organs and calculated effective dose in children under condition of 0.5 mmPb lead clothes wrapping shielding measure in non-scanning areas,and without taking any protective measures,and studied the shielding effect of lead clothes in children head CT examination.Results For the head CT examinations of the one-year old phantom,compared with no shielding,the doses of main organs such as thyroid,lung,stomach,intestine and breast,reduced at least 40.4%,and the effective dose reduced from 4.9 mSv to 2.2 mSv by 55.7%.For the head CT examinations of the ten-year old phantom,compared with no shielding,the doses reduced at least 39.5%,and the effective dose reduced from 2.4 mSv to 1.7 mSv by 30.5%.Conclusion Shielding protection can significantly decrease the effective dose and the absorbed dose of tissues and organs in children.