Application of high-resolution CT local augmentation reconstruction to improve the accurate diagnosis of small pulmonary nodule structure

Objective To explore the accurate display method of the local structure of small CT nodules in lung. Methods Close the automatic radiation dose adjustment technique. Keep the thickness of the phantom was 2 mm, the interval between the phantom layers was 2 mm, the pitch was 1, and the reconstructed convoluted nucleus was B80s. Group A controlled the scanning matrix FOV to be 500 mm×500 mm, 400 mm×400 mm, 300 mm×300 mm, 200 mm×200 mm and 100 mm×100 mm, while group B controlled the scanning matrix FOV to be 500 mm×500 mm. Use these parameters to scan the catphan 500 phantom, a routine chest CT conditioned scanning quality control model. The original data raw data were used to reconstruct the FOV to be 400 mm×400 mm, 300 mm×300 mm, 200 mm×200 mm and 100 mm×100 mm under the scanning FOV to be 500 mm×500 mm. All other conditions are consistent. Observe the high contrast resolution module of Catphan 500 phantom, and compare the line logarithms of two groups of images under different scanning FOV or different reconstruction FOV. Thirty-five patients with small pulmonary nodules from February 2018 to March 2018 of the Second Affiliated Hospital of Zhejiang University Medical College were retrospectively collected. The raw data were used to reconstruct the images. The FOV was 320 mm×320 mm in the conventional reconstruction group and 100 mm×100 mm in the local magnification reconstruction group. The subjective score data of the two groups were compared by using rank-sum test. Results When catphan 500 phantom was used, the number of lines in group A and group B increased gradually with the decreasing of FOV. The subjective score of local magnification reconstruction group (4.77±0.35) was higher than that of conventional reconstruction group (3.86±0.50) and the difference was statistically significant (Z=-5.763, P<0.05). Conclusion Local magnification and reconstruction of high-resolution CT images can achieve the same image quality as local magnification, local magnification and reconstruction of image quality is significantly better than simple image magnification. Key words: Tomography,X-ray computed; Radiation dosage; Imaging quality; Comparative study