用^(137)Cs放射源替代^(18)F检验PET专用工作箱屏蔽效果的换算公式

The Conversion Formula on Examining Shielding Effect of the PET Special Box Using ^(137)Cs Source as a Substitute for ^(18)F

为了检验PET专用工作箱对18Fγ射线的屏蔽效果,采用γ点源吸收剂量率的计算公式,并以137Cs替代18F,推导出一个换算公式。依据此计算公式,只需测量137Csγ点源在参考点处的吸收剂量率,便可由换算公式计算出18F在参考点相应活度的吸收剂量率。这些吸收剂量率为评价PET专用工作箱对18F的屏蔽效果提供了可靠数据。用此换算公式计算某医院正在使用的PET专用工作箱中18F参考点处的吸收剂量率,并与现场检测结果比较,结果显示,两种方法所得结果基本一致。说明用137Cs放射源替代18F检验PET专用工作箱的屏蔽效果是可行的。

In order to test the γ shielding effect of PET special working-boxes to ^18F, the conversion formula using calculate formula of γ point-source absorbed dose rate and substitute ^137Cs for ^18F is deduced. Only the absorbed dose rate of ^137Cs sealed source is measured at the reference point, the absorbed dose rate of ^18F can also be calculated at the same preference point according to the convetsion formula. The shielding effect of PET special working-boxes to ^18F can be evaluated by means of these calculated data. These calculate data using this conversion formula is basically accordant with the measured data at site.