A Method to Improve Electron Density Measurement of Cone-Beam CT Using Dual Energy Technique

Area of Science:

• Medical Physics
• Radiotherapy Technology
• Imaging Science

Background:

• Accurate electron density measurement is crucial for radiation dose calculation in radiotherapy.
• Cone-beam CT (CBCT) is widely used for image-guided radiotherapy, but its electron density accuracy can be limited.
• Beam hardening artifacts in CBCT can further compromise electron density estimation.

Purpose of the Study:

• To develop and validate a novel dual-energy imaging method for CBCT.
• To improve the accuracy of electron density measurements using CBCT.
• To reduce beam hardening artifacts in CBCT-based electron density calculations.

Main Methods:

• Utilized the XVI CBCT system on an Elekta Synergy linac.
• Acquired projection data using high and low energy X-ray beams.
• Developed a basis material decomposition model for quantitative evaluation via phantom simulations and experiments.
• Reconstructed CBCT images of basis material coefficients and calculated electron densities.

Main Results:

• The dual-energy method achieved electron density values within 2% of theoretical values.
• A correlation coefficient of approximately 1.0 was observed between calculated and theoretical values.
• The method significantly reduced beam hardening artifacts compared to conventional CBCT.

Conclusions:

• A novel dual-energy CBCT imaging method for electron density calculation has been successfully developed.
• The method provides more accurate electron density values.
• This technique offers a potential platform for improved dose calculation in radiotherapy.