Multi-institutional study on image quality for a novel CBCT solution on O-ring linac.

Area of Science:

• Medical Imaging
• Radiological Physics

Background:

• A novel cone beam computed tomography (CBCT) system's image quality was assessed in a multi-institutional setting.
• The study aimed to evaluate the consistency of imaging performance across different institutions using this new CBCT technology.

Purpose of the Study:

• To investigate the consistency of imaging performance of a novel CBCT system across multiple institutions.
• To evaluate key image quality parameters including relative electron density (RED) to Hounsfield Unit (HU) relationship, uniformity, contrast-to-noise ratio (CNR), and spatial resolution.

Main Methods:

• Six institutions imaged phantoms using Ethos and Halcyon units with HyperSight CBCT.
• Imaging protocols varied in tube potential (100–140 kVp) and exposure (80–800 mAs).
• Performance was assessed via RED vs. HU, uniformity, CNR, slice thickness, circular symmetry, and modulation transfer function (MTF).

Main Results:

• Consistent performance was observed in radial uniformity (1–7 HU), circular symmetry (within one-pixel), and integral nonuniformity (1–10).
• RED-to-HU relationship showed some variability for RED > 1, dependent on exposure, but no outliers were found.
• Spatial resolution (MTF at 10%/50%) was 0.55 ± 0.01 mm⁻¹ / 0.35 ± 0.02 mm⁻¹; CNR varied with contrast levels and kVp(mAs).

Conclusions:

• The multi-institutional CBCT analysis demonstrated consistent imaging performance in uniformity, symmetry, contrast, and spatial resolution.
• Variability in the RED-to-HU relationship was noted, influenced by exposure levels.
• Further data from diverse institutions are recommended for establishing robust quality assurance metrics.