Functional MRI for radiotherapy dose painting.

Area of Science:

• Radiation Oncology
• Medical Imaging
• Radiotherapy Physics

Background:

• Modern radiation therapy allows precise dose delivery, sparing healthy tissues and enabling higher curative doses.
• Dose painting, a technique modulating radiation dose spatially, exploits variations in tumor radiation sensitivity.
• Functional imaging is crucial for identifying high-sensitivity sub-regions within tumors for dose painting.

Purpose of the Study:

• To review the integration of magnetic resonance imaging (MRI) into external radiotherapy workflows for dose painting.
• To discuss the application of MRI-based functional imaging techniques for guiding radiation dose painting.
• To address challenges and clinical developments in MRI-guided dose painting.

Main Methods:

• Review of current literature on MRI techniques (diffusion-weighted MRI, dynamic contrast-enhanced MRI) for radiotherapy.
• Discussion of technical considerations for MRI in treatment position, including patient setup and coil selection.
• Emphasis on geometrical accuracy and high-resolution quantification of functional parameters from multiparametric MRI data.

Main Results:

• MRI offers superior soft tissue contrast compared to CT, aiding in tumor delineation.
• Diffusion-weighted MRI reflects cell density, indicating tumor load, while dynamic contrast-enhanced MRI reflects vascularity and oxygenation, impacting radiation sensitivity.
• Technical adaptations are needed for MRI in treatment position, and geometrical accuracy is critical for precise dose painting.

Conclusions:

• MRI-guided dose painting holds significant potential for improving radiotherapy outcomes by tailoring radiation doses to tumor heterogeneity.
• Addressing technical challenges in MRI acquisition and data quantification is essential for successful clinical implementation.
• Further clinical developments are expected to enhance the precision and effectiveness of MRI-guided dose painting strategies.