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

Objective: to assess the possibilities of using low-dose computed tomography (LDCT) in children and adolescents with pulmonary tuberculosis (TB).Material and methods. The design of the study, which included patients aged 2–17 years with active pulmonary TB and post-TB changes treated in Central Tuberculosis Research Institute in 2021–2023, consisted of two parts as follows: part 1 (a prospective selective study) – independent assessment of LDCT vs standard-dose CT (SDCT) diagnostic accuracy by two radiologists in 44 patients with TB process stabilization; part 2 – cohort one-time assessment of LDCT image quality in 144 patients at different phases of TB treatment. LDCT was performed on the Somatom Emotion 16 CT scanner (Siemens, Germany) by filtered backprojection algorithm; SDCT was conducted on the Somatom go.Up CT scanner by iterative reconstruction algorithm. In patients aged 2–12 years, pediatric protocols, and in patients aged 13–17, standard protocols were used. Radiation exposure was evaluated considering the effective dose (ED).Results. In patients aged 13–17 years, the noise level was lower and the signal-to-noise ratio was higher with LDCT for all anatomical structures, with the exception of pulmonary parenchyma. In patients aged 2–12 years, the signal-to-noise ratio was the same or slightly higher in SDCT. In the subjective assessment, good image quality was noted with a high correlation between the assessments of radiologists. ED was 2.17 times lower for LDCT than for SDCT in adolescents and 1.91 times lower in children. In patients aged 2–3 years, the quality essentially depended on their immobility during the procedure, though under sedation it was good in 92% of cases.Conclusion. In conditions of sufficient immobility of the patient, LDCT provided good image quality of tuberculous changes with a decrease in ED compared to SDCT by 2.17 times in adolescents and by 1.91 times in children.

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Results of the clinical evaluation of the low-dose protocols of the digital linear tomography of the chest

Камышанская

Cheremisin

Водоватов

et al. 2020

Radiac. gig. (2008)

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High levels of tuberculosis morbidity in the Russian Federation lead to the extensive use of X-ray diagnostics for the tuberculosis screening and assessment of the effectiveness of treatment. Digital radiography and computed tomography are traditionally used for the diagnostics of tuberculosis. These methods are associated with significant drawbacks: low specificity for radiography, high costs per examination, significant patient doses, and limited availability for computed tomography. As an additional method for the assessment of the effectiveness of the tuberculosis treatment it is possible to use linear tomography performed on the digital X-ray units. The aim of the current study was to evaluate the possibility of utilization of the digital linear tomography for the control of the effectiveness of tuberculosis treatment in a dedicated antitubercular medical facility. The study was divided in two stages. The first stage was aimed at the assessment of the diagnostic image quality of the digital linear tomograms obtained using the previously developed low-dose imaging protocols. Image quality assessment was performed using an anthropomorphic chest phantom and dedicated imitators of the lung lesions. Image quality was assessed by the experts (radiologists) based on the developed image quality criteria. Results of the first stage of the study indicate that all low-dose protocols allow obtaining images with at least acceptable image quality. Hence it was possible to propose low-dose protocols for clinical evaluations. The second stage of the study was performed as a prospective cohort survey aimed at the evaluation of the structure of X-ray examinations, patient doses and clinical image quality of the digital linear tomograms in antitubercular early treatment center. The cohort survey included two patient samples, uniform by age and gender composition, anthropometric characteristics and structure of diagnosis. One of the samples was imaged using standard (vendor) digital linear protocols, other – using the proposed low-dose protocols. Dose data collection (measurement of dose-area product and subsequent calculation of effective dose) and expert image quality assessment was performed for each patient. The results of the second stage of the study indicate that the use of the low-dose protocols allow reducing the patient effective doses per examination up to a factor of 6–8 (0.56 – 5.9 mSv for standard protocols; 0.2 – 1.15 mSv for low-dose protocols) due to the reduction in tube current-time product (126 mean mAs and 11 mean mAs, respectively). The dose reduction is accompanied by the reduction in the image quality of the linear tomograms (from “excellent” or “good” for standard protocols to “acceptable” for low-dose protocols). However, that dose not hinder the conclusion decision and identification of pathologies. Results of the study indicate that digital linear tomography can be used for the evaluation of the dynamics of the pathological process in the lungs with the previously defined localization of the pathology. The presented low-dose protocols were implemented into radiological practice of the antitubercular early treatment center. Currently, the proposed low-dose protocols are under evaluation for the large-scale study on the base of general practice hospitals

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

Cited by 8 publications

References 17 publications

Comparison of different approaches for image quality assessment in computer tomography

Comparison of different approaches for image quality assessment in computer tomography

Experience in Using Low-Dose Computed Tomography in Children and Adolescents with Pulmonary Tuberculosis

Results of the clinical evaluation of the low-dose protocols of the digital linear tomography of the chest

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