Comparative evaluation of volume and helical four-dimensional computed tomography using canon system.

Area of Science:

• Medical Imaging
• Radiotherapy Physics
• Radiation Oncology

Background:

• Four-dimensional computed tomography (4DCT) enhances tumor and organ motion evaluation by capturing respiratory dynamics.
• 4DCT utilizes volume (cine) and helical scanning modes, necessitating a comparative analysis for clinical application.
• Understanding the trade-offs between these 4DCT modes is crucial for optimizing radiotherapy planning.

Purpose of the Study:

• To compare volume and helical 4DCT scan modes.
• Evaluate image quality, dimensional accuracy, and positional accuracy for respiratory-gated radiotherapy.
• Determine the optimal 4DCT mode based on clinical objectives.

Main Methods:

• Utilized a Canon Aquilion ONE Prism CT scanner with an Anzai respiratory gating system.
• Assessed volume and helical 4DCT modes under identical parameters using a motion phantom.
• Quantitatively evaluated image quality, dimensional accuracy, and positional accuracy in phantom and clinical datasets.

Main Results:

• Volume mode demonstrated superior dose efficiency and dimensional consistency, especially under rapid motion.
• Helical mode achieved higher positional accuracy and temporal resolution but with increased radiation dose.
• Clinical data corroborated phantom findings, showing reduced dimensional errors with volume mode and better motion representation with helical mode.

Conclusions:

• Volume mode is advantageous for applications prioritizing spatial accuracy and reduced radiation exposure.
• Helical mode excels in precise respiratory motion tracking due to superior temporal resolution.
• Optimizing respiratory-gated radiotherapy requires careful selection of 4DCT scan mode and system settings.