Novel technique of craniospinal axis proton therapy with the spot-scanning system: avoidance of patching multiple fields and optimized ventral dose distribution.
OBJECTIVE
Conventional craniospinal irradiation (CSI) is a complex procedure carrying a high risk of adverse side effects. Still, it is indispensable for cure in a number of pediatric brain tumors. In this study, the feasibility and the potential advantage of spot-scanning proton therapy for CSI are investigated.


METHODS
A boy (5.5 years of age) with a recurrent medulloblastoma received CSI with a single posterior field using the spot-scanning system at Paul Scherrer Institute. Dose distribution to the targets and the organs at risk, treatment time, reproducibility of patient positioning, toxicity (according to EORTC/RTOG score), and treatment outcome were evaluated.


RESULTS
The plan achieved a homogeneous coverage of the target volume, even using a single field. The doses to the organs ventral to the target were minimized. During treatment, grade 1 skin reaction and grade 2 central nervous system toxicity were observed. After 2 months, the boy presented with a transitory fatigue. After 24 months, he is alive and free of disease. Growth hormones and thyroid hormones are reduced.


CONCLUSIONS
These results, based on a single patient, suggest that spot-scanning proton therapy for craniospinal treatment is feasible and safe. By applying a single dorsal field, difficulties of multiple-field patching can be avoided and the ventral dose spread can be minimized.
Timmermann
Beate
B
Center for Proton Radiation Therapy, Paul Scherrer Institute, Villigen, Switzerland. beate.timmermann@psi.ch
Lomax
Antony Jonathan
AJ
Nobile
Luisa
L
Grotzer
Michael Andreas
MA
Weiss
Markus
M
Kortmann
Rolf-Dieter
RD
Bolsi
Alessandra
A
Goitein
Gudrun
G
D002528:Cerebellar Neoplasms / Q000532:radiotherapy*; D002675:Child, Preschool; D016371:Cranial Irradiation / Q000295:instrumentation*; D018572:Disease-Free Survival; D019583:Dose Fractionation, Radiation; D004867:Equipment Design; D006801:Humans; D008297:Male; D008527:Medulloblastoma / Q000532:radiotherapy*; D009364:Neoplasm Recurrence, Local / Q000532:radiotherapy*; D061766:Proton Therapy; D011832:Radiation Injuries / Q000209:etiology / Q000517:prevention & control; D011855:Radiodermatitis / Q000209:etiology / Q000517:prevention & control; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation*; D020266:Radiotherapy, Conformal / Q000295:instrumentation*; D012984:Software; D013116:Spinal Cord / Q000528:radiation effects*; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*; D016896:Treatment Outcome; D011522:Protons
D011522:Protons