Comparison Of Three-dimensional Reconstructions At Low Dose And Conventional Dose CT In Patients With Gastro-intestinal Tract Disease

Gastro-intestinal tract disease is very common in clinic. Gastro-intestinal tumor is one of the most common cancer in China. There are many examination methods for digestive system, including fibroendoscopy, pneumo-barium double contrast examination and 3 dimentional reconstruction of CT. With the rapid development of computer technology, 3 dimentional reconstruction becomes an ideal examination modality for gastro-intestinal tract diseases, especially for protuberant lesions. But the application of it is restricted by the high radiation dose and high cost. We try to evaluate the difference of image quality and radiation dose between low dose and conventional dose CT in patients with gastro-intestinal tract disease.Objective: To evaluate the difference of image quality and radiation dose between low dose and conventional dose MSCT in patients with gastro-intestinal tract disease.Methods 30 patients with gastro-intestinal tract disease were scanned with MSCT by conventional mAs (120 mAs). They were divided into 3 groups randomly, and were scaned by low dose (30mA, 20mA, 10mA, respectively) again. 3 dimentional reconstruction images, including CTVE, VR, MPR, were obtained. Then we evaluated the difference of image quality and radiation dose among diffenrent dose group.Results :The radiation dose of 30mAs group is 25% of 120mAsgroup, 20 mAs group is 16.67% of 120mAs group, and 10 mAs group is only 8.33%.The image quality of CTVE and VR showed no difference between 30mAs and 120mAs group. The displays of parenchymatous organs, lesion and changes inside the lesion were different in MPR images, which influenced the location diagnosis, but not nature diagnosis. The deformation of VR and CTVE increased in 20mAs group compared to 120mAs. There was difference in image quality, which did not influence diagnosis. The displays of lesion, depth of invasion, relationship with adjacent tissue and parenchymatous organs were not clear, which influenced diagosis. The deformation of VR and CTVE in 10mAs was so severe that influence the diagnosis. The structures in MPR images were not clear at all.Conclusion: The imge quality of CTVE and VR by low dose 30mAs is not evidently different with 120mAs. It can be applied for the screening for gastro-intestinal tract diseases, follow-up of operations, and can be a substitution for fibroendoscopy.