Proton Radiotherapy for Midline Central Nervous System Lesions: A Class Solution

Area of Science:

• Radiation Oncology
• Neurosurgery
• Medical Physics

Background:

• Conventional radiotherapy (RT) for midline and central brain lesions poses challenges in avoiding dose to organs at risk (OAR).
• Standard RT techniques often result in treating large volumes of healthy brain tissue unnecessarily.

Purpose of the Study:

• To evaluate the efficacy of proton radiotherapy (PrT) as a class solution for midline and central brain lesions.
• To assess the dosimetric advantages of PrT in sparing organs at risk compared to conventional RT.

Main Methods:

• Retrospective review of 24 patients with midline central nervous system (CNS) lesions treated between 2005 and 2013.
• Dosimetric analysis of target volume coverage and OAR dose avoidance using proton beams in the midsagittal plane.

Main Results:

• Meningiomas (8), craniopharyngiomas (6), and other deep midline tumors (10) were the most common histologies.
• PrT using midsagittal beams achieved minimal dose to the brain stem (mean 18.4 Gy RBE) and hippocampi (mean 15.8 Gy RBE).
• Prescribed doses ranged from 48.6-62.5 Gy RBE, with a median of 54.0 Gy RBE to the planning target volume.

Conclusions:

• Proton radiotherapy is considered an optimal treatment modality for midline CNS lesions.
• Modified midsagittal PrT techniques enable effective treatment while sparing uninvolved brain structures.