Animal tissue-based quantitative comparison of dual-energy CT to SPR conversion methods using high-resolution gel...

Area of Science:

• Medical Physics
• Radiotherapy
• Biomedical Imaging

Background:

• Accurate tissue characterization is crucial for ion therapy treatment planning.
• Estimating tissue properties like stopping power ratio (SPR) is essential for precise dose deposition.
• Dual-energy computed tomography (DECT) shows promise for improving SPR estimation compared to single-energy CT (SECT).

Purpose of the Study:

• To compare the accuracy of SPR values derived from DECT and SECT using various published algorithms.
• To evaluate the performance of DECT and SECT in a realistic phantom setup with fresh animal tissues.
• To benchmark SPR accuracy using gel dosimetry and ionization chambers.

Main Methods:

• A phantom containing fresh animal tissues (beef, pork) and water was irradiated in a clinical proton therapy facility.
• Dosimetric polymer gel was used to measure 3D proton range distributions.
• SPR values were calculated from proton ranges and compared between DECT and SECT algorithms.
• Ionization chambers were used to benchmark gel dosimetry accuracy.

Main Results:

• SPR measurements from gel dosimetry and ionization chambers showed high consistency (0.2% mean deviation).
• DECT-based algorithms achieved significantly better accuracy (0.3% average deviation) than SECT (1.2% average deviation) for SPR prediction.
• Gel dosimetry successfully captured intra-sample range variations up to 5 mm.

Conclusions:

• DECT demonstrates a significant advantage over SECT for accurate stopping power prediction in realistic scenarios.
• This study provides a comprehensive comparison of multiple DECT and SECT algorithms under identical conditions.
• Findings support the use of DECT for enhanced accuracy in ion therapy treatment planning.