An approach for measuring the spatial orientations of a computed-tomography simulation system

Area of Science:

• Medical Physics
• Radiological Imaging Technology
• Quality Assurance in Medical Imaging

Background:

• Quality assurance (QA) for CT simulators involves complex spatial orientation measurements.
• Current methods for assessing tabletop, laser, and imaging plane alignment are time-consuming.

Purpose of the Study:

• To develop a simple, efficient method for measuring spatial angular deviations in CT simulators.
• To reduce the time required for QA procedures in CT simulation.

Main Methods:

• Utilized an in-house cross-jig to establish relationships between jig arm orientations and CT component alignments.
• Performed two CT scans: one aligning the jig with the tabletop, another with external lasers.
• Verified the method against AAPM Task Group 66 (TG 66) recommendations and known misalignment errors.

Main Results:

• The proposed method accurately measures angular deviations between the tabletop, external lasers, couch, and imaging plane.
• Testing time was reduced significantly to 5 minutes compared to the standard 30 minutes.
• Maximum error in measured angles was only 0.07°, demonstrating high precision.

Conclusions:

• The cross-jig method offers a faster and simpler alternative for CT simulator spatial orientation QA.
• Accurate quantification of angular deviations allows for precise error correction.
• The approach is adaptable for quality assurance in other imaging systems like PET-CT and MRI.