Technical considerations for noncoplanar proton-beam therapy of patients with tumors proximal to the optic nerve.
OBJECTIVE
To investigate technical feasibilities of noncoplanar proton-beam therapy (PBT) on dose reduction to critical organs.


METHODS
The degree of mechanical precision, rotational limitations of the gantry and the treatment couch were evaluated, and dose-volume histograms were compared for noncoplanar and coplanar PBT. Following these studies, three patients with tumors proximal to the optic nerve underwent noncoplanar PBT.


RESULTS
Noncoplanar PBT offered advantage in dose reduction to the optic nerve when compared to coplanar therapy. This advantage was more significant if the tumor reduced in size during treatment. None experienced radiation injury to the optic nerve during a short follow-up time of 7-12 months.


CONCLUSIONS
Noncoplanar PBT appears to reduce doses to organs at risk.
Mizumoto
Masashi
M
Proton Medical Research Center, University of Tsukuba, Ibaraki, Japan. mizumoto1717@hotmail.com.|Proton Medical Research Center, University of Tsukuba, Tennoudai, Tsukuba, Ibaraki, 305-8575, Japan. mizumoto1717@hotmail.com.
Nakayama
Hidetsugu
H
Proton Medical Research Center, University of Tsukuba, Ibaraki, Japan.
Tokita
Mari
M
Alpert Medical School of Brown University, Providence, RI, USA.
Sugahara
Shinji
S
Proton Medical Research Center, University of Tsukuba, Ibaraki, Japan.
Hashii
Haruko
H
Proton Medical Research Center, University of Tsukuba, Ibaraki, Japan.
Sakae
Takeji
T
Proton Medical Research Center, University of Tsukuba, Ibaraki, Japan.
Tsuboi
Koji
K
Proton Medical Research Center, University of Tsukuba, Ibaraki, Japan.
Sakurai
Hideyuki
H
Proton Medical Research Center, University of Tsukuba, Ibaraki, Japan.
Tokuuye
Koichi
K
Proton Medical Research Center, University of Tsukuba, Ibaraki, Japan.|Department of Radiology, Tokyo Medical University, Tokyo, Japan.
D008949:Adenoma, Pleomorphic / Q000532:radiotherapy*; D001932:Brain Neoplasms / Q000532:radiotherapy*; D019583:Dose Fractionation, Radiation; D005142:Eyelid Neoplasms / Q000532:radiotherapy*; D005260:Female; D005625:Frontal Lobe / Q000528:radiation effects*; D005909:Glioblastoma / Q000532:radiotherapy*; D006801:Humans; D008577:Meningeal Neoplasms / Q000532:radiotherapy*; D008579:Meningioma / Q000532:radiotherapy*; D008875:Middle Aged; D009897:Optic Chiasm / Q000528:radiation effects; D009900:Optic Nerve / Q000528:radiation effects*; D010315:Particle Accelerators; D061766:Proton Therapy; D011832:Radiation Injuries / Q000517:prevention & control*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012160:Retina / Q000528:radiation effects; D017356:Synchrotrons; D011522:Protons
D011522:Protons