A dedicated cone-beam CT system for musculoskeletal extremities imaging: design, optimization, and initial...

Area of Science:

• Medical Imaging
• Radiology
• Biomedical Engineering

Background:

• Conventional CT and MRI are mainstays for musculoskeletal imaging.
• There is a need for dedicated systems offering clinical and logistical advantages.
• Musculoskeletal (MSK) radiology, orthopaedic surgery, and rheumatology can benefit from advanced imaging solutions.

Purpose of the Study:

• To report the design and initial imaging performance of a dedicated cone-beam CT (CBCT) system for MSK extremities.
• To evaluate the system's potential to complement existing imaging modalities.
• To explore advantages for diagnosis, treatment planning, and therapy response assessment.

Main Methods:

• Scanner design incorporated clinical requirements, including weight-bearing knee imaging in a natural stance.
• Theoretical modeling (cascaded systems analysis of MTF and DQE) and physical experimentation were employed.
• Key components: flat-panel detector (FPD) and low-power X-ray source on a retractable C-arm for versatile scanning orientations.

Main Results:

• System geometry optimized for sub-millimeter spatial resolution (MTF 50% at 1.3 mm⁻¹).
• Nominal technique (90 kVp, 0.3 mm Cu filtration) suggested for high imaging performance at reduced dose (6.4-15 mGy).
• Experimental studies demonstrated improved image uniformity and CNR with an antiscatter grid; cadaver images showed excellent bone and soft-tissue detail.

Conclusions:

• The proposed CBCT system is expected to deliver volumetric extremity images with diagnostic CT-equivalent soft-tissue contrast and enhanced spatial resolution at potentially lower doses.
• Cascaded systems analysis proved valuable for efficient system design and optimization.
• The prototype system offers potential advantages including reduced size and cost, load-bearing extremity imaging, and integration with real-time fluoroscopy and digital radiography.