Methodology for the Evaluation of Image Quality and Radiation Dose in Cone-Beam Computed Tomography O-Arm

Abstract

Cone beam computed tomography (CBCT) equipment has been widely used in image-guided interventional procedures, requiring its characterization in both quality assurance and quality control programs. Despite the recent publication of some guides and studies in the literature, there is still no consensus on which tests, methodologies and performance standards should be used for the routine quality control of this equipment. In this respect, from the review of the methodologies and performance standards suggested in the literature for CBCT equipment, choices were made of the methods with the greatest feasibility for assessing image quality and dosimetric characterization for tomographic acquisition (3D) of a CBCT model O equipment -Arm™ O2 (Medtronic Inc.). The tests carried out were: uniformity, noise, geometric precision and slice thickness, voxel density (CT number) and its linearity, low contrast resolution, high contrast spatial resolution and computed tomography dose index (CTDI) for skull, abdomen, chest and extremity procedures in the various protocols (different exposure modes and biotypes) configured by the manufacturer . In the study, monitoring of the area around the equipment was also performed, simulating the performance of a typical procedure. The equipment showed linearity of the voxel density scales with good performance of spatial resolution and CTDI values below the recommended reference levels, but poor uniformity and low contrast resolution, reinforcing that the same performance standards as conventional CT should not be used. The results obtained in this study provide references for future evaluations of this type of equipment, contributing to the definition of which tests and methodologies should be used routinely in quality control programs.