Adjustable shunts and proton therapy: a magnetic combination

Area of Science:

• Medical Physics
• Pediatric Oncology
• Neurosurgery

Background:

• Compact proton beam therapy (PBT) systems are increasingly used for pediatric central nervous system (CNS) tumors.
• These systems generate magnetic fields that may interact with implanted medical devices.
• Pediatric CNS tumor patients often have adjustable cerebrospinal fluid (CSF) shunts, typically manipulated by magnets.

Discussion:

• The potential for magnetic fields from PBT to alter adjustable CSF shunt settings in pediatric patients is a clinical concern.
• This study investigated the in vivo and ex vivo effects of PBT magnetic fields on adjustable CSF shunts.
• Understanding this interaction is crucial for patient safety during PBT.

Key Insights:

• No unintentional changes in adjustable CSF shunt settings were observed in vivo during PBT in the first five pediatric patients.
• Ex vivo testing demonstrated that PBT magnetic fields can alter shunt settings when the shunt is positioned near the PBT exit beam.
• This suggests a localized magnetic field effect that may not manifest during standard in vivo treatment.

Outlook:

• While this small cohort showed no in vivo interference, continued vigilance is necessary.
• A low threshold for checking shunt function post-PBT or in symptomatic patients is recommended.
• Further research with larger patient cohorts is needed to fully elucidate the long-term safety of PBT in patients with adjustable CSF shunts.