Multienergy element-resolved cone beam CT (MEER-CBCT) realized on a conventional CBCT platform

Area of Science:

• Medical Imaging
• Radiation Oncology
• Computational Imaging

Background:

• Cone Beam CT (CBCT) is crucial in radiation therapy for patient positioning.
• Current CBCT primarily provides anatomical information, limiting advanced applications.
• There is a need for enhanced CBCT capabilities beyond anatomical imaging.

Purpose of the Study:

• To propose and validate a multi-energy element-resolved (MEER) CBCT framework.
• To enable simultaneous reconstruction of x-ray attenuation coefficients, relative electron density (rED), and elemental composition (EC).
• To support advanced applications in radiation therapy through improved image characterization.

Main Methods:

• Implementation of the MEER-CBCT framework on a Varian TrueBeam CBCT platform using kVp-switching.
• Formulation of a simultaneous image reconstruction and elemental decomposition model as an optimization problem.
• Utilizing spatial regularization and consistency constraints for accurate reconstruction, solved via alternating-direction minimization.

Main Results:

• Successful realization of the MEER-CBCT framework on a clinical platform.
• Simulation studies showed significantly improved attenuation coefficient images (SSIM 0.98 vs. 0.61).
• Experimental studies demonstrated high contrast-to-noise ratio (≥60) and low median errors for rED (1.4%) and EC (2.3%).

Conclusions:

• A novel MEER-CBCT framework was successfully developed and implemented on a clinical CBCT system.
• The framework accurately reconstructs x-ray attenuation coefficients, rED, and EC simultaneously.
• MEER-CBCT shows significant potential for advancing radiation therapy applications through detailed material decomposition.