Photon vs. proton radiochemotherapy: Effects on brain tissue volume and perfusion

Area of Science:

• Neuro-oncology
• Radiation Oncology
• Medical Imaging

Background:

• Glioblastoma treatment involves radiochemotherapy, potentially affecting healthy brain tissue.
• Understanding structural and hemodynamic changes in contralateral brain tissue is crucial for treatment optimization.

Purpose of the Study:

• To compare the effects of photon and proton radiochemotherapy on healthy brain tissue volume and perfusion.
• To investigate the relationship between radiation dose and brain tissue changes.

Main Methods:

• Sixty-seven glioblastoma patients underwent photon or proton radiochemotherapy with temozolomide.
• T1-weighted and arterial spin labeling MRI were used to assess brain volume and perfusion changes before and after treatment (3-6 months).

Main Results:

• Photon therapy led to significant gray matter (GM) and white matter (WM) volume decrease (-2.2% and -1.2%, respectively).
• Proton therapy showed no significant GM or WM volume changes (0.3% and -0.4%, respectively).
• GM volume loss correlated with radiation dose and differed between modalities; perfusion decrease was comparable but not statistically significant in proton therapy patients.

Conclusions:

• Brain tissue volume loss is dependent on radiation dose and modality.
• Proton therapy may offer a benefit in preserving brain volume compared to photon therapy.
• Perfusion changes were similar between modalities, suggesting volume preservation as a key differentiator.