Total-Body PET/CT Imaging after Proton Craniospinal Irradiation in Pediatric Patients: A Brief Report.

PURPOSE: This study aims to report rapid off-line total-body PET/CT imaging on pediatric patients after proton craniospinal irradiation (CSI), which enabled visualization of the entire craniospinal axis together with whole-body redistribution of proton-induced activity. METHODS AND MATERIALS: Three pediatric patients with medulloblastoma or pineoblastoma underwent 60-minute dynamic single-bed total-body PET/CT scans shortly after proton CSI using a rapid near-room transfer workflow. PET data were reconstructed into consecutive 5-minute frames and cumulative acquisitions to characterize regional temporal changes and acquisition-duration-dependent image variability. RESULTS: PET visualized activity along the full craniospinal irradiation axis and in extra-field major blood vessels and blood-rich organs. Regional PET signal decreased by 92.0-94.8% in the cranial and spinal regions and by 89.4-91.9% in the cardiac blood pool, liver, and spleen from the 0-5-minute to the 55-60-minute frame, reflecting the combined effects of physical decay and biological washout. The first 5 minutes of PET data depicted the major whole-body distribution pattern, whereas acquisitions of approximately 20-30 minutes substantially reduced regional image variability. CONCLUSION: Rapid total-body PET/CT enabled single-bed visualization of the full craniospinal irradiation axis and quantitative characterization of whole-body temporal evolution after proton CSI.