Robust quantitative contrast-enhanced dual-energy CT for radiotherapy applications

Area of Science:

• Medical Physics
• Radiotherapy Imaging
• Dual-Energy Computed Tomography

Background:

• Accurate quantification of iodine-based contrast agents is crucial for medical imaging.
• Virtual noncontrast imaging aids in radiotherapy planning by providing baseline tissue parameters.
• Dual-energy CT (DECT) offers advanced material decomposition capabilities.

Purpose of the Study:

• To develop and validate precise methods for determining iodine content using DECT.
• To create accurate virtual noncontrast maps of physical parameters like electron density.
• To assess these methods in the context of radiotherapy applications.

Main Methods:

• A simulation environment was used to compare three decomposition methods: two-material, three-material (with volume constraint), and eigentissue decomposition.
• Methods were evaluated with and without prior knowledge of tissue composition, using simulated and patient DECT data with iodine contrast.
• Experimental calibration involved imaging tissue-equivalent materials and contrast solutions with known compositions.

Main Results:

• Two-material decomposition showed robustness and minimal bias when tissue composition was known a priori.
• Eigentissue decomposition demonstrated minimal bias and high robustness without prior tissue composition knowledge.
• Experimental calibration and patient data confirmed the accuracy and negligible bias of both methods for clinical use.

Conclusions:

• Two accurate DECT methods were identified for quantifying iodine contrast agents and virtual noncontrast composition.
• Two-material decomposition is suitable for organ-specific assessments (e.g., kidney function) with known tissue components.
• Eigentissue decomposition is valuable for radiotherapy planning requiring accurate dose calculations without contrast agent information.