TU-E-BRA-08: A Comprehensive Study on the Relationship between Image Quality and Imaging Dose in Low-Dose Cone Beam...

Area of Science:

• Medical Physics
• Radiological Imaging
• Radiation Oncology

Background:

• Image-guided radiation therapy (IGRT) relies on accurate imaging for treatment delivery.
• Low-dose cone beam CT (CBCT) is crucial for IGRT to minimize patient radiation exposure.
• Compressive sensing (CS) techniques offer potential for further dose reduction in CBCT.

Purpose of the Study:

• To determine optimal low-dose scan protocols for CS-based CBCT.
• To investigate the impact of projection number and tube load on image quality.
• To achieve high image quality at reduced radiation doses for IGRT applications.

Main Methods:

• Performed CS-based CBCT reconstruction across a range of projection numbers (46-364) and mAs/view (0.2-2.4).
• Assessed image quality for each scanning protocol combination.
• Analyzed optimal protocols based on image quality metrics for various IGRT tasks.

Main Results:

• Image quality degradation is minimal (>100 total mAs) but significant below 40 total mAs.
• Image quality varied by 5.74% to 17.16% RMSE on iso-low-dose lines.
• Optimal protocols involve a medium number of projections and medium mAs/view, especially for low-contrast or high-resolution objects.

Conclusions:

• Optimal low-dose CS-based CBCT protocols likely range from 40-100 total mAs.
• Protocols with fewer than 50 projections are most challenging at constant low doses.
• Clinically acceptable doses are task-dependent: 72.8 mAs for low-contrast objects, 12.2 mAs for high-contrast objects >3mm.