Application of energy spectrum purification technique in chest CT of physical examiners with different BMI

Objective To explore the application of energy spectrum purification technique in chest CT of physical examiners with different body mass index(BMI), so as to formulate a more reasonable low-dose scanning scheme for chest CT physical examination.Methods A total of 100 physical examiners who underwent chest CT scan in the Affiliated Hospital of Yangzhou University in 2020 and 2021 were enrolled, including 20 cases of BMI(kg/m²)<18.5, 20 cases of 18.5≤ BMI<24, 20 cases of 24≤BMI<28, 20 cases of 28≤BMI<32, and 20 cases of BMI≥32. Physical examiners using 2021 scanning scheme were set as a research group, while those with 202 scanning scheme was set as a control group. For the research group, the following scanning parameters were used: tube voltage Sn100 kV, reference tube current 240 mAs, and pitch 1.5. For the control group, tube voltage 100 kV, reference tube current 280 mAs and pitch 1.5 were used. CARE Dose 4D was utilized by both groups. The images obtained were evaluated by two physicians. Kappa analysis was performed for the evaluation consistency test. The image quality and effective dose(ED) of lung window and mediastinum window in the two groups were analyzed by variance analysis and t test, and the radiation dose and radiation dose reduction degree of different BMI examiners were compared.Results Compared with the research group, different BMI control groups showed no statistical difference in lung window image score(P>0.05), but presented statistical difference in mediastinal window image score(P<0.05). There was no statistical difference in noise value and contrast noise ratio(P>0.05). Statistical difference was found in ED value(P<0.05). Compared with the control group, different BMI research group presented 70.5%, 72.2%, 75.4%, 77.7% and 80.2% decreases in ED, respectively. The degree of radiation dose reduction was proportional to BMI.Conclusions Compared with traditional 100 kV scanning, energy spectrum purification technique can ensure the quality of images, greatly reduce the radiation dose of examiners in chest CT physical examination, which is more conducive to reduce the radiation dose of those with larger BMI.