Gantry-based cone-beam CT of the thoracolumbar spine: A phantom comparison with Photon-Counting CT and Energy-Integrating CT.

Abstract

<h4>Background</h4>While cone beam CT (CBCT) is commonly used in musculoskeletal imaging of the extremities, its application in spinal imaging has been restricted by small field-of-view (FOV) coverage. Recent advancements in gantry-based CBCT systems promise to enable comprehensive imaging of the spinal column.<h4>Purpose</h4>This study aimed to evaluate the performance of a novel gantry-based, multi-scan CBCT system for spinal imaging with complete anatomic coverage and compare it to energy integrating (EI)CT and photon counting (PC)CT using dose-matched protocols.<h4>Materials and methods</h4>An anthropomorphic torso phantom was used to simulate human anatomy. Gantry-based CBCT scans of the thoracolumbar spine were performed using different presets (low-dose, enhanced, best quality), while EICT and PCCT scans followed dose-matched clinical protocols. Qualitative image analysis was assessed by three blinded readers using a 4-point Likert scale, and quantitative analysis was conducted using global noise level (GNL) measurements.<h4>Results</h4>CBCT achieved diagnostic-quality imaging for the thoracic and lumbar spine, particularly with "best" and "enhanced" presets. Subjective image quality was highest for PCCT, followed by EICT and CBCT. CBCT demonstrated lower GNL than EICT, nearing PCCT levels. However, high radiation doses (5 mGy) were required for CBCT imaging of the upper thoracic spine (Th1-Th6) due to anatomical complexity, while low doses (0,5 mGy) sufficed for the lower thoracolumbar spine (Th7-S1).<h4>Conclusion</h4>Gantry-based CBCT was able to generate diagnostic-quality images of large spinal regions at relatively low radiation doses in a phantom setting, although the upper thoracic spine (above Th6) required higher doses. The overall subjective image quality remained below EICT and PCCT.