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J Radiat Res. 2019 May 21. pii: rrz022. doi: 10.1093/jrr/rrz022. [Epub ahead of print]

Clinical experience of craniospinal intensity-modulated spot-scanning proton therapy using large fields for central nervous system medulloblastomas and germ cell tumors in children, adolescents, and young adults.

Author information

1
Department of Radiation Medicine, Faculty of Medicine, Hokkaido University.
2
Global Station for Quantum Medical Science and Engineering, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University.
3
Department of Radiation Oncology, Faculty of Medicine, Hokkaido University.
4
Proton Beam Therapy Center, Hokkaido University Hospital.
5
Department of Neurosurgery, Faculty of Medicine, Hokkaido University.
6
Department of Pediatrics, Faculty of Medicine, Hokkaido University.
7
Department of Radiation Oncology, Hokkaido University Hospital.
8
Division of Quantum Science and Engineering, Faculty of Engineering, Hokkaido University.
9
Department of Statistical Data Science, The Institute of Statistical Mathematics.

Abstract

The outcomes of intensity-modulated proton craniospinal irradiation (ipCSI) are unclear. We evaluated the clinical benefit of our newly developed ipCSI system that incorporates two gantry-mounted orthogonal online X-ray imagers with a robotic six-degrees-of-freedom patient table. Nine patients (7-19 years old) were treated with ipCSI. The prescribed dose for CSI ranged from 23.4 to 36.0 Gy (relative biological effectiveness) in 13-20 fractions. Four adolescent and young adult (AYA) patients (15 years or older) were treated with vertebral-body-sparing ipCSI (VBSipCSI). Myelosuppression following VBSipCSI was compared with that of eight AYA patients treated with photon CSI at the same institution previously. The mean homogeneity index (HI) in the nine patients was 0.056 (95% confidence interval: 0.044-0.068). The mean time from the start to the end of all beam delivery was 37 min 39 s ± 2 min 24 s (minimum to maximum: 22 min 49 s - 42 min 51 s). The nadir white blood cell, hemoglobin, and platelet levels during the 4 weeks following the end of the CSI were significantly higher in the VBSipCSI group than in the photon CSI group (P = 0.0071, 0.0453, 0.0024, respectively). The levels at 4 weeks after the end of CSI were significantly higher in the VBSipCSI group than in the photon CSI group (P = 0.0023, 0.0414, 0.0061). Image-guided ipCSI was deliverable in a reasonable time with sufficient HI. Using VBSipCSI, AYA patients experienced a lower incidence of serious acute hematological toxicity than AYA patients treated with photon CSI.

KEYWORDS:

adolescents and young adults; beam delivery time; craniospinal irradiation; hematologic toxicity; intensity-modulated spot-scanning proton therapy; vertebral body sparing

PMID:
31111946
DOI:
10.1093/jrr/rrz022

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