Phantom-derived method for improving accurate material decomposition in photon-counting detector CT

Photon-counting detector CT (PCD-CT) enables spectral imaging with material separation. Accurate iodine and iron quantification remains challenging due to inevitable low- and high-energy base material CT number mismatches and dual-energy ratio (DER) variability. This study develops and validates a correction method addressing these issues to improve iodine and iron quantification in PCD-CT.

A spectral CT abdomen phantom containing rods with known iodine (0.5-15.0 mg/mL) and iron (2.0-25.0 mg/mL) concentrations in water- and liver-equivalent material was scanned on a clinical PCD-CT under varying tube voltages, dose levels, and with/without a fat ring. High- and low-energy CT numbers of base materials and DER values were inputs for the correction method. Material concentrations calculated with and without correction were validated against known phantom values.

The correction method significantly reduced quantification errors. Iodine errors fell below 5% for concentrations ≥ 2 mg/mL and iron errors below 15% for concentrations ≥ 5 mg/mL. Without correction, errors reached up to 83% (iodine) and 85% (iron) at low concentrations, reduced to 23% and 47%, respectively, after correction.

The proposed correction method improves accuracy in spectral material decomposition for PCD-CT, supporting its potential for better clinical assessment of lesion contrast enhancement, therapy response and hepatic burden evaluation.

This technical note introduces a phantom-based correction method for photon-counting detector CT that improves iodine and iron quantification by addressing base material Hounsfield Unit (HU) mismatches and dual-energy ratio variability. The method reduces quantification errors and offers a practical calibration procedure, supporting the potential for clinically reliable iodine and iron quantification.

PCD-CT correction method reduces concentration errors across varying scan protocols and configurations. Implementation guide supports adaptation to other scanners. Accurate iodine and iron quantification supports diagnosis and treatment assessment.