X射线能量对剂量计测量CT辐射剂量的影响OA

Objective:The point dose and volume CT dosimetry index(CTDIvol)at different X-ray energies were measured using the Raysafe-X2 air ionization chamber(referred to as"RX2"),the Piranha CT dose profiler semiconductor ionization chamber(referred to as"CDP"),and the 30013 Farmer air ionization chamber(referred to as"PT3"),in order to explore the effect of X-ray energy on the radiation dose evaluation by different dose meters.Methods:The tube voltage settings for each layer were as follows:single energy mode included 80kV,90kV,100kV,120kV,140kV,and 150kV(Sn);dual energy mode included 70/150kV(Sn),80/150kV(Sn),90/150kV(Sn),100/150kV(Sn),and 80/140kV.The tube current was manually adjusted to ensure that the CTDIvol for each group was approximately 20 mGy,and the displayed CTDIvol and DLP were recorded.Point dose values were measured at the center,0-point,3-point,6-point,and 9-point positions of the 32cm phantom using CDP and PT3.The actual CTDIvol was measured and calculated using RX2,CDP,and PT3.Results:(1)Point Dose:In single energy mode(except for Sn150kV),CDP measured higher point doses at the center compared to PT3.At low energies,the point dose measured by CDP at non-center positions was 75%higher than that of PT3,while at high energies,88%of the point doses measured by PT3 were higher than those measured by CDP.In dual energy mode(except for 90+Sn150kV),CDP measured higher point doses at the center compared to PT3.However,except for 80+140kV,PT3 measured higher point doses than CDP at non-center positions.(2)As for CTDIvol,the measured values were as follows:RX2 measured(18.89±0.38)mGy,CDP measured 18.31(19.25,20.84)mGy,and PT3 measured(20.35±0.38)mGy.Except when CDP was used at 150kV(Sn),the CTDIvol measured by all three dose meters for other X-ray energies ranged between 16～24mGy.Conclusion:Different dosimeters exhibit varying responses to X-ray energy.Therefore,selecting an appropriate dosimeter is crucial depending on the measurement conditions and objectives.