Electron Paramagnetic Resonance pO₂ Image Tumor Oxygen-Guided Radiation Therapy Optimization.

Area of Science:

• Oncology
• Medical Physics
• Radiotherapy

Background:

• Current radiation therapy planning does not incorporate tumor oxygenation levels.
• Tumor oxygenation is strongly correlated with radiation treatment outcomes.
• Hypoxic tumor regions are often radio-resistant and associated with treatment failure.

Purpose of the Study:

• To develop and validate an oxygen-guided radiation therapy (OGRT) protocol for preclinical rodent models.
• To integrate electron paramagnetic resonance (EPR) imaging with intensity-modulated radiation therapy (IMRT) for precise dose delivery.
• To investigate the potential of OGRT to improve cancer radiation treatment efficacy.

Main Methods:

• Developed an OGRT protocol using EPR imaging for high-resolution tumor oxygenation mapping.
• Utilized an XRAD225Cx micro-CT/therapy system for radiation delivery.
• Implemented a two-step radiation plan: initial uniform dose followed by a booster dose to hypoxic regions.
• Employed 3D-printed tungsten-infused polymer blocks for conformal beam shaping.

Main Results:

• Achieved sub-millimeter precision in radiation delivery.
• Demonstrated high dose accuracy in targeting hypoxic tumor areas.
• Successfully integrated EPR imaging with IMRT for real-time treatment adaptation.
• Preliminary efficacy testing is underway on FSa fibrosarcoma tumors in mice.

Conclusions:

• OGRT represents a promising advancement in cancer radiation therapy planning and delivery.
• Precise targeting of hypoxic tumor regions with radiation can potentially overcome radio-resistance.
• The developed OGRT protocol shows potential for enhancing treatment outcomes in preclinical models.