Résumé
Objective To study the CT number and noise of HT MVCT on different dose rate and scanning thickness.Methods The CT number of different relative electron density were measured in the MVCT image of Cheesephantom with tissue substitute plugs scanned with different dose rate and slice thickness.The physical density corresponding to the CT number was plotted as the image value to density table (IVDT).The noise was measured in the MVCT image of Cheesephantom with solid water plugs scanned with different dose rate and slice thickness.Results There was a significant different of the CT number of the plugs with different dose rates (P =0.000),it shows a positive correlation between the varied CT number and density (R2 =0.846),there is larger impact on the high density number.There was still a significant effect on the noise with different dose rate (P =0.000 density),the noise increase as the dose rate decrease.There was no significant effect on IVDT (P =1.000) and noise (P =0.667) with different slice thickness.Conclusions The CT number and the noise vary with the dose rate,the QA of MVCT should be performed regularly to assure the quality of image and the accuracy of dose calculating on MVCT in adaptive.