Comparison of Proton Versus Photon SBRT for Treatment of Spinal Metastases Using Variable RBE Models

International Journal of Particle Therapy, 2025 · DOI: https://doi.org/10.1016/j.ijpt.2025.100743 · Published: January 1, 2025

Oncology

Simple Explanation

This study compares proton and photon radiation therapies for treating spinal metastases, focusing on how each method affects the tumor and surrounding healthy tissues. Proton therapy's effectiveness can vary, especially near the end of the radiation beam, which is important when treating areas close to sensitive structures like the spinal cord. The research uses models to estimate the biological impact of proton radiation, comparing it to traditional photon radiation to see which provides better tumor coverage while minimizing harm to nearby tissues.

Study Duration

Not specified

Participants

Nine patients with spinal metastasis

Evidence Level

Not specified

Key Findings

1
Proton therapy (IMPT) significantly improved planning target volume coverage compared to photon therapy (PH-SBRT) at both 30 Gy and 45 Gy doses.
2
IMPT at 30 Gy(RBE) and 45 Gy(RBE) resulted in significantly lower maximum doses to the spinal cord compared to PH-SBRT.
3
Variable RBE models showed that fixed RBE models may underestimate the maximum dose to adjacent OARs, particularly the spinal cord expansion.

Research Summary

This study compares proton SBRT to photon SBRT for spinal metastases, using variable RBE dose models to assess the impact on target coverage and sparing of organs at risk. The results suggest that IMPT may offer improved target coverage and better sparing of adjacent OARs compared to photon SBRT. The study also indicates that fixed RBE models might underestimate the maximum dose to adjacent OARs, highlighting the need for biologically optimized treatment plans.

Practical Implications

Improved Target Coverage

IMPT can potentially enhance the radiation dose delivered to the tumor, leading to better local control.

Enhanced OAR Sparing

Proton therapy may reduce the risk of radiation-induced toxicities by minimizing exposure to critical structures like the spinal cord.

Refined RBE Modeling

The use of variable RBE models can lead to more accurate dose estimations and potentially safer treatment plans.

Study Limitations

1
Limited in vivo RBE models using human tissue
2
Absence of robust evaluation and incorporation of biologically optimized treatment plans
3
Lack of a special RBE model for spinal SBRT

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