Non-invasive experimental determination of a CT source model

Area of Science:

• Medical Physics
• Radiological Imaging
• X-ray Technology

Background:

• Accurate characterization of X-ray source models is crucial for computed tomography (CT) scanner performance.
• Bow tie filters (BT) significantly shape the X-ray beam, influencing image quality and dose distribution.
• Existing methods for BT filter characterization may have limitations in precision or applicability.

Purpose of the Study:

• To present non-invasive methods for determining equivalent X-ray source models of CT scanners.
• To develop and apply a high-precision technique, Time Resolved Integrated Charge (TRIC), for BT filter characterization.
• To evaluate the performance of TRIC by comparing it with the COBRA method.

Main Methods:

• Developed and utilized the TRIC technique to measure integrated charge over time.
• Employed two dose probes: a solid-state detector and an ionization chamber, with a correction method for the solid-state probe's energy dependence.
• Assessed equivalent thicknesses of Aluminum (Al) and Polymethyl methacrylate (PMMA) for BT filters, first assuming single-component materials, then two-component materials.

Main Results:

• TRIC successfully characterized BT filters, providing equivalent Al and PMMA thicknesses across various tube high voltages.
• The two-component material assumption provided a more accurate representation of equivalent BT filters.
• TRIC results showed good agreement when compared with the real BT filter shapes and the COBRA method.

Conclusions:

• The TRIC method offers a precise, non-invasive approach for characterizing CT scanner bow tie filters.
• TRIC enables the determination of equivalent material thicknesses, crucial for accurate X-ray source modeling.
• TRIC provides a valuable alternative to existing methods, with potential applications in both research and clinical settings.