Evaluation of image quality with different field of view in CT scan of the body in children

Objective To evaluate the relationship between field of view (FOV) and quality of CT images. Methods Scanning of the phantoms of spatial resolution and density resolution was performed with FOVs of 25 cm×25 cm, 35 cm×35 cm, and 42 cm×42 cm, respectively, and the spatial resolution and density resolution of CT images with different FOVs were measured. 20 patients underwent CT scanning using 25 cm×25 cm and 35 cm×35 cm FOVs, respectively. The images were evaluated by 3 qualified CT doctors by using a double-blind reading. Results As FOVs changed, the spatial resolution and density resolution were different. The best spatial resolution and density resolution were obtained on 25 cm×25 cm FOV images. The best spatial resolution could distinguish four 0.6 mm-diameter eyelets, and the best density resolution could distinguish five 2.5 mm-diameter eyelets. The CT images with 25 cm×25 cm FOV were obviously better than those with 35 cm×35 cm FOV (P0.05). Conclusion On the range of conventional FOV of CT, the spatial resolution and density resolution of CT images are the best when 25 cm×25 cm FOV is used.