Improving dose calculation accuracy in preclinical radiation experiments using multi-energy element resolved...

Area of Science:

• Medical Physics
• Radiological Imaging
• Pre-clinical Research

Background:

• Cone-beam CT (CBCT) is crucial for image guidance and experiment planning in small-animal radiation research.
• Accurate quantitative imaging is needed for precise Monte Carlo-based radiation dose calculations.
• Existing CBCT systems require enhanced capabilities for material decomposition.

Purpose of the Study:

• To implement multi-energy element-resolved (MEER) CBCT for quantitative imaging.
• To determine relative electron density (rED) and elemental composition (EC) for improved dose calculations.
• To validate the MEER-CBCT system on a pre-clinical small-animal radiation research platform.

Main Methods:

• Performed comprehensive geometry, intensity, and artifact corrections for CBCT calibration.
• Acquired multi-energy scans (30, 40, 60 kVp) and reconstructed CBCT images.
• Utilized an optimization approach to derive rED and EC images from corrected CBCT data.

Main Results:

• Reduced artifacts from geometry inaccuracy, detector lag, glare, and beam hardening.
• Decreased CT number mean errors from 19% to 5%.
• Achieved median errors below 1% (H), 2% (O), 4% (Ca) for elemental fractions and <5% for rED.
• Improved Monte Carlo dose calculation accuracy in bone regions, reducing mean dose error from 47.5% to 10.9%.

Conclusions:

• The implemented MEER-CBCT system achieves accurate material decomposition on a small animal irradiation platform.
• This quantitative imaging approach significantly enhances the accuracy of Monte Carlo dose calculations.
• MEER-CBCT is a valuable tool for advancing pre-clinical radiation research.