Application Of IDose Iterative Reconstruction Technique On CT Of Pelvic Malignant Tumors With Low Radiation Dose

ObjectiveTo compare the quality and lesion conspicuity of images of pelvic malignant tumorpatients which acquired on computed tomographic with standard-dose and low-dose withiDose iterative reconstruction, evaluate the application of iDose iterative reconstructiontechnique for low dose CT of pelvic malignant tumors.Materials and methods120pelvic malignant tumor patients (have had any treatment), whose body massindex were normal, were selected in this study. They were divided into four groups atrandom (group A~group D), everyone of these patients were performed the pelvicenhanced CT scan with standard radiation dose CT (120kV;250mAs), and reconstructedusing filtered back projection (FBP), and then scanned with low radiation dose (group A:100kV;250mAs, group B:80kV;250mAs, group C:120kV;125mAs, group D:120kV;75mAs). The low-dose images were reconstructed separately with FBP and with threelevels iterative reconstruction (iDose2, iDose4, iDose6). Three radiologists record volumeCT dose index (CTDIvol), dose-length product (DLP), effective dose (ED), noise,signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Objective image quality,lesion conspicuity, and visibility of small structures were graded by using five-point scaleand diagnostic confidence was assessed by using a four-point scale. Data were analyzed byusing analysis of variance and the Wilcoxon signed rank test with SPSS. Results1. Image quality: Both the objective and subjective ratings of low-dose CT imageswere improved with iDose iterative reconstruction. The low-dose images in Group A andgroup C with iDose4iterative reconstruction obtained identical image quality as thestandard-dose ones. The low-dose images in Group D with iDose6iterative reconstructiongot the same image quality as the standard-dose ones. The images in group B could notmeet the diagnostic requirements even if the application of iDose6iterative reconstruction.2. Radiation dose: The quality of low-dose images reconstructed with iDose6iterativereconstruction in Group D had met the diagnostic requirements. CTDIvolvalues, DLP andED were5.47±0.015mGy,156.09±8.16mGy·cm,2.97±0.15mSv, respectively in gropeD.ConclusionsThe iDose technique allows radiation dose reduction for pelvic malignant tumor CTexaminations whereas improving image quality to meet the diagnostic requirements.