Optimization of acquisition parameters for reduced-dose thoracic CT: A phantom study

Area of Science:

• Radiology
• Medical Imaging
• Radiation Dose Optimization

Background:

• Computed tomography (CT) is crucial for chest imaging.
• Reducing radiation dose is a key goal in clinical practice.
• Balancing dose reduction with image quality is essential for diagnostic accuracy.

Purpose of the Study:

• To analyze the impact of reduced-dose CT parameters on image noise and pulmonary structure visibility.
• To identify optimal parameters for ultra-low dose chest CT in routine clinical practice.

Main Methods:

• Chest phantom CT scans acquired at varying low dose levels (0.15-0.40 mGy CTDIvol).
• Parameters manipulated included tube voltage, pitch factor, and rotation time.
• Images reconstructed with adaptive statistical iterative reconstruction (ASIR) at 70% and 100%; signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) calculated; pulmonary structure visibility assessed by readers.

Main Results:

• High tube voltage yielded the best image quality and SNR/CNR.
• Lower pitch factor and higher tube current decreased visibility, particularly in the lung periphery.
• Dose reduction from 0.40 to 0.30 mGy showed no significant visual score decrease, but reduction to 0.15 mGy significantly lowered visibility.
• ASIR-v100% reduced noise more than ASIR-v70% without significantly altering visibility scores.

Conclusions:

• High tube voltage is recommended for reduced-dose CT protocols.
• Decreased SNR and CNR do not always correlate with reduced visibility of pulmonary structures.