The development and clinical use of a beam ON-LINE PET system mounted on a rotating gantry port in proton therapy.
OBJECTIVE
To verify the usefulness of our developed beam ON-LINE positron emission tomography (PET) system mounted on a rotating gantry port (BOLPs-RGp) for dose-volume delivery-guided proton therapy (DGPT).


METHODS
In the proton treatment room at our facility, a BOLPs-RGp was constructed so that a planar PET apparatus could be mounted with its field of view covering the iso-center of the beam irradiation system. Activity measurements were performed in 48 patients with tumors of the head and neck, liver, lungs, prostate, and brain. The position and intensity of the activity were measured using the BOLPs-RGp during the 200 s immediately after the proton irradiation.


RESULTS
The daily measured activity images acquired by the BOLPs-RGp showed the proton irradiation volume in each patient. Changes in the proton-irradiated volume were indicated by differences between a reference activity image (taken at the first treatment) and the daily activity-images. In the case of head-and-neck treatment, the activity distribution changed in the areas where partial tumor reduction was observed. In the case of liver treatment, it was observed that the washout effect in necrotic tumor cells was slower than in non-necrotic tumor cells.


CONCLUSIONS
The BOLPs-RGp was developed for the DGPT. The accuracy of proton treatment was evaluated by measuring changes of daily measured activity. Information about the positron-emitting nuclei generated during proton irradiation can be used as a basis for ensuring the high accuracy of irradiation in proton treatment.
Nishio
Teiji
T
Particle Therapy Division, Research Center for Innovative Oncology, National Cancer Center, Kashiwa. tnishio@east.ncc.go.jp
Miyatake
Aya
A
Ogino
Takashi
T
Nakagawa
Keiichi
K
Saijo
Nagahiro
N
Esumi
Hiroyasu
H
D000465:Algorithms; D001932:Brain Neoplasms / Q000000981:diagnostic imaging; D004867:Equipment Design; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy; D008297:Male; D009369:Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D009862:Online Systems; D049268:Positron-Emission Tomography / Q000295:instrumentation* / Q000379:methods; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy; D061766:Proton Therapy; D011859:Radiography; D015203:Reproducibility of Results; D012399:Rotation; D013679:Technology, Radiologic / Q000295:instrumentation / Q000379:methods; D011522:Protons
D011522:Protons