Pencil Beam Scanning Proton Therapy for Paediatric Neuroblastoma with Motion Mitigation Strategy for Moving Target...

Area of Science:

• Radiation Oncology
• Pediatric Oncology
• Medical Physics

Background:

• Minimizing late radiation side-effects in pediatric patients is crucial.
• Pencil beam scanning proton therapy (PBS-PT) offers tissue sparing but faces challenges from respiratory motion interplay effects.
• Volumetric rescanning (vRSC) is a technique to mitigate motion during PBS-PT.

Purpose of the Study:

• To report clinical experience with motion mitigation using vRSC in pediatric neuroblastoma patients treated with PBS-PT.
• To evaluate the outcomes and safety of PBS-PT with vRSC in this cohort.
• To assess the clinical relevance of vRSC in managing respiratory motion.

Main Methods:

• Nineteen pediatric neuroblastoma patients received PBS-PT (median dose 21 Gy RBE).
• Motion assessment using four-dimensional computed tomography (4D CT) was performed for a subset of patients.
• vRSC was employed for motion mitigation in seven patients, with 4D dose calculations guiding its use.

Main Results:

• No local recurrences were observed with a median follow-up of 14.9 months.
• The 2-year overall survival was 94%, and 2-year distant progression-free survival was 76%.
• Acute toxicity (grade 2-4) was 11%, with no late toxicities observed during the follow-up period. vRSC showed minimal impact on target dose coverage.

Conclusions:

• PBS-PT demonstrated excellent early outcomes for pediatric neuroblastoma patients.
• PBS-PT with vRSC is logistically feasible and safe in this patient group.
• The necessity of vRSC for anesthetized children with <5 mm motion requires further clinical evaluation.