Optimization of low-dose chest CT protocols for the evaluation of the ground glass nodules using different iterative reconstruction algorithms

Abstract

Rapid development and implementation of the computed tomography (CT) in the Russian radiological practice reads to the significant increase in both the individual patient doses and collective dose of the Russian population from computed tomography. For the successful implementation of the optimization and dose reduction techniques it is necessary to develop and implement the methods of subjective (expert) image quality assessment. The current study was focused on the development of the composite method of the CT image quality assessment using an anthropomorphic chest phantom and imitators of the nodules for the detection of the ground-glass nodules. The method includes the detection of the nodules on the CT scan series as well as the assessment of the quality of the images using 5-grade Likert scale corresponding to the designed criteria. The method was evaluated for the development of the preliminary low-dose chest CT protocols using different reconstruction algorithms. The results of the study were based on the expert opinion of ten radiologists. They indicate the possibility of the significant (up to a factor of four) reduction of the effective doses of the patients related to the reduction of mAs for the CT scans of the chest for the detection of ground-glass nodules without a reduction in image quality. The best results corresponded to the algorithm of the model iterative reconstructions. Results of the study would be further evaluated on patients within a dedicated clinical trial.