ISSN (Online): 2720-8796
CASE REPORT
The Role and Significance of Ultra-Low Dose Computed Tomography in Assessing Lung Injury During Viral Infections
Irakli Tortladze1, Grigol Nemsadze1,ID, Otar Urushadze1, Giorgi Apkhazava1,ID, Ketevan Karanadze1, Mariam Labuchidze1
ABSTRACT
Seasonal influenza causes millions of severe respiratory infections annually, leading to an increased incidence of acute lung injury and pneumonia. Traditional two-projection X-ray examinations often have limited sensitivity and specificity in diagnosing viral-induced lung injuries. Insights from the COVID-19 pandemic have highlighted the superior diagnostic accuracy of modern computed tomography (CT) in detecting viral pneumonia. In the present case report, we demonstrate high specificity (>95%) of individualized ultra-low-dose CT (ULDCT) in detecting infiltrative changes, including peribronchial injuries. The radiation dose of ULDCT was 30 times lower than that of standard CT scans and significantly lower than traditional X-rays. While the visualization quality for mediastinal structures and the skeletal system was reduced, the assessment of lung tissue remained precise and reliable. Its high sensitivity, specificity, and minimal radiation exposure make it particularly advantageous for patients requiring multiple follow-up scans. Implementing targeted protocols based on individual patient needs is recommended to increase ULDCT usage over conventional X-ray imaging for lung assessments.
Keywords: Chest X-ray (CXR); dose length product (DLP); low-dose computed tomography (LDCT); scanogram; ultra-low-dose computed tomography (ULDCT)..
DOI: 10.52340/GBMN.2025.01.01.115
INTRODUCTION
Seasonal influenza (the flu) is one of the most common respiratory infectious diseases globally. Annual seasonal epidemics cause 3 to 5 million complicated, severe hospital cases.1
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During seasonal outbreaks, the incidence of acute lung injury and pneumonia significantly increases, leading to a higher risk of hospitalization. In Georgia, the peak of seasonal influenza epidemics occurs in late autumn and early winter.1
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When a patient presents with clinical features of respiratory infections, the standard diagnostic radiological method is a two-projection chest X-ray examination; however, the choice of projections depends on the radiologist.2
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It is essential to note that the sensitivity and specificity of traditional radiological examinations in diagnosing lung injuries resulting from viral infections are often limited.3
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Considering the experience gained during the COVID-19 pandemic, when modern high-tech computed tomography demonstrated specificity and sensitivity greater than 95% in diagnosing viral pneumonia,4 we aimed to utilize computed tomography (CT) selectively during seasonal influenza outbreaks. When clinical and laboratory data suggested an infectious etiology of lung tissue damage, CT was performed based on clinical indications and individual patient parameters.5
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Recently, the use of CT scans in daily life has increased. As a result, there is growing interest in scanning protocols, the work of radiographers, the protocols they use, and the amount of radiation patients receive. This is a significant issue in our country because most radiographers rely on automatic protocols, ultimately increasing the radiation dose.
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Significant challenges exist today regarding the quality of radiology services, as highlighted in a 2014 study, a master's thesis, and a 2020 research work from the Master's Program in Biomedical Engineering at the Technical University (Health Policy, Economics, and Sociology, 2015; 1(1); 'Quality Problems in Medicine in Georgia').
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In this article, we aimed to demonstrate the advantages of ultra-low-dose CT (ULDCT) modality for evaluating lung tissue under minimal radiation exposure, with a focus on the extent and severity of infiltrative changes.6
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All patients discussed in this article were selected from 127 patients admitted to the First University Clinic from November 2024 to January 2025, who had clinical indications for a radiological assessment.
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Modern standard CT scanners have individualized parameters that automatically adjust based on changes to the scanogram grid. We studied radiation dose statistics for chest CT scans in leading Georgia clinics, with an average DLP of 350-450. Within our study, patients meeting inclusion criteria underwent ULDCT adjusted for BMI (Body Mass Index) with their consent.
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During the chest scanogram, a CT scan was performed in a single projection (preferably a direct projection), with individualized adjustments to the scanogram grid size to ensure optimal image quality.
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Each patient received an informational brochure detailing the principles of CT imaging, an individualized protocol design based on their body mass index (BMI), and the differences from the standard protocol preloaded into the diagnostic equipment. The study adhered to the fundamental optimization principle, recognizing the potential need for multiple radiological assessments during hospitalization.
CASES
Case 1
A young patient experiencing fever and cough for several days was admitted to the clinic. Based on the doctor's assessment and depending on the symptoms, an X-ray examination was deemed necessary. After evaluating the X-ray results (Fig.1), a computed tomography (CT) scan was considered, and the patient underwent standard CT imaging using an integrated protocol (Fig.2).
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FIGURE 1. Case 1. Plain X-ray examination (Direct projection) with Eff Dose pf 0,1mSv: left upper lobe infiltration
​FIGURE 2. Case 1. A. Left upper lobe consolidation (lung window); B. CT scan shows the same patient with the radiation dose, total DLP, and parameters window
The same patient later underwent a follow-up ULDCT scan for lung tissue assessment, receiving 30 times less radiation exposure than the initial scan (BMI 23.7).
​Despite the lower visualization quality of mediastinal structures and the skeletal system, lung tissue assessment was satisfactory for monitoring purposes (Fig.3).
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FIGURE 3. Case 1. A. Coronal view lung window; B. Axial view soft tissue window: shows residual fibrotic changes in the left upper lobe after the virus
Case 2
The patient was admitted to the clinic with a 5-day history of a sub-febrile condition and general weakness. The complete blood count was practically unchanged. Following the initial X-ray, a low-dose CT scan was performed with the patient's consent, revealing infiltrative changes in the right peribronchial area (Fig.4).
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FIGURE 4. Case 2. Initial radiologic examination. A. Axial view of chest CT scan, lung window, shows right upper lobe, peribronchial infiltrative changes; B. The same patient with a soft tissue window
After five days of treatment, the patient showed no clinical improvement, with worsening laboratory markers (CRP >150). Follow-up ULDCT confirmed disease progression (Fig.5).
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FIGURE 5. Case 2. Radiologic examinations after 5 days of treatment. A. Axial CT scan of chest and lung window shows proper upper lobe infiltration and left lung intraparenchymal high-density focal infiltration; B. Image of the same patient with very low DLP of 6.30
Figure 6 shows the follow-up plain X-ray and ultra-low-dose CT after the home treatment period.
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FIGURE 6. Case 2. A. Plain X-ray examination; B. Axial CT scan, lung window with tiny fibrotic area in the right lung and very low DLP of 4.80
DISCUSSION
The study demonstrated that ULDCT is a far more reliable and effective diagnostic tool than conventional X-ray imaging in managing seasonal viral pneumonia. Its primary advantage lies in its high sensitivity and specificity, which enable early detection of the extent and severity of infiltrative changes.7,8
ULDCT was particularly effective for hospitalized patients requiring dynamic lung monitoring, as the low radiation dose minimized cumulative exposure risks, a critical factor for multiple examinations.9
CONCLUSIONS
Ultra-low-dose computed tomography (ULDCT) is a highly safe and effective radiological tool for diagnosing and monitoring lung parenchymal damage caused by seasonal viral infections. It is particularly recommended for patients requiring multiple follow-up scans.
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Considering individual patient needs, targeted protocols should be implemented to increase the use of ULDCT over conventional X-ray imaging for assessing lung tissue.
AUTHOR AFFILIATION
1 Department of Radiology, The First University Clinic of TSMU, Tbilisi State Medical University, Tbilisi, Georgia
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