Merging Orthovoltage X-Ray Minibeams spare the proximal tissues while producing a solid beam at the target.

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Technology

Background:

• Conventional brain tumor radiation therapy can cause significant cognitive deficits, especially in pediatric patients.
• Minibeam radiation therapy (MBRT) utilizes arrays of narrow beams to spare healthy tissues.
• Orthovoltage X-ray Minibeams (OXM) adapt MBRT principles using lower energy X-rays.

Purpose of the Study:

• To investigate the efficacy and dosimetric characteristics of Orthovoltage X-ray Minibeams (OXM) for brain tumor treatment.
• To evaluate the potential of OXM to spare proximal tissues, such as the cerebral cortex.
• To assess the feasibility of implementing OXM in advanced radiotherapy techniques like VMAT.

Main Methods:

• Experimental characterization of OXM dosimetry using radiochromic films.
• Monte Carlo simulations to determine physical absorbed dose distributions.
• Application of a first-order biologic model to predict tissue sparing and tolerance.
• Comparison of OXM beam penumbra with conventional 6-MV X-ray beams.

Main Results:

• OXM dosimetry was characterized, demonstrating its physical properties.
• Monte Carlo simulations provided absorbed dose data and biologic models predicted improved tissue tolerance.
• A 220-kVp orthovoltage beam exhibited a 5-fold sharper lateral penumbra compared to a 6-MV X-ray beam.
• The OXM method is compatible with arc-scan and VMAT delivery techniques.

Conclusions:

• OXM presents a promising technique for brain tumor radiotherapy, potentially reducing cognitive side effects.
• The method offers advantages in dose enhancement with contrast agents and is suitable for low-resource settings due to its low cost and portability.
• OXM technology could improve treatment outcomes and accessibility in radiation oncology.