不同扫描体位和定位像方向对单髋关节CT图像及辐射剂量影响OACSTPCD

To investigate the effect of different scanning positions and scout orientation on image quality and radiation dose in CT scanning of unilateral hip with automatic tube current modulation(ATCM).120 patients who underwent CT examination of single hip were randomly divided into 4 groups.In group A,the body midline was used as the sagittal vertical orientation line,a scout image was anteroposterior+left side,and the scanning field of view was large body type.In the other three groups,the hip was taken as the center of the isocenter scanning,and the scanning field of view was small body type.In group B,the orientation of the scout image was anteroposterior+lateral image of the X-ray tube close to the long axis of the body.The orientation of group C was anteroposterior+lateral image of the X-ray tube away from the long axis of the body.Only anteroposterior direction is used for group D scout image.The volume CT dose index(CTDIvol),dose length product(DLP),objective noise,signal-to-noise ratio(SNR)and contrast signal-to-noise ratio(CNR)were measured and calculated.Three subjective measures(Subjective noise,streak artifacts and diagnostic confidence)were evaluated.The objective noise,SNR,CNR,CTDIvol and DLP were significantly different among the four groups(P＜0.01).There was no significant difference between group C and group D(P＞0.05),The overall radiation dose of group C and D was reduced by 16％-35％compared with other groups.There was no significant difference in all subjective indexes among the four groups(P＞0.05).In the case of unilateral hip CT scan in the ATCM system based on the information of the last scout view,it is recommended to select the small body scanning field of view in the isocenter scanning scheme,and select the anteroposterior scout image or the lateral scout image of the X-ray tube away from the long axis of the body as the last execution plan,which can ensure the image quality and further optimize the radiation dose.