Program Information
Feasibility Study of Fiber-Optic Cerenkov Radiation Sensors for in Vivo Measurement: Dosimetric Characterization and Clinical Application in Proton Beams
J LAH1*, J Son2, G Kim3 , D Shin4 , (1) Myongji Hospital, Goyang-si, Korea, (2) Korea University,Seoul,Korea, (3) University of California, San Diego, La Jolla, CA,(4) National Cancer Center, Goyang-si,Korea
Presentations
SU-G-TeP2-15 (Sunday, July 31, 2016) 4:30 PM - 5:00 PM Room: ePoster Theater
Purpose:To evaluate the possibility of a fiber-optic Cerenkov radiation sensor (FCRS) for in vivo dose verification in proton therapy.
Methods:The Cerenkov radiation due to the proton beam was measured using a homemade phantom, consisting of a plastic optical fiber (POF, PGS-CD1001-13-E, Toray, Tokyo, Japan) connected to each channel of a multi-anode photomultiplier tube (MAPMT:H7546, Hamamatsu Photonics, Shizuoka, Japan). Data were acquired using a multi-anode photomultiplier tube with the NI-DAQ system (National Instruments Texas, USA). The real-time monitoring graphic user interface was programmed using Labview. The FCRS was analyzed for its dosimetrics characteristic in proton beam. To determine the accuracy of the FCRS in proton dose measurements, we compared the ionization chamber dose measurements using a water phantom. We investigated the feasibility of the FCRS for the measurement of dose distributions near the superficial region for proton plans with a varying separation between the target volume and the surface of 3 patients using a humanoid phantom.
Results:The dose-response has good linearity. Dose-rate and energy dependence were found to be within 1%. Depth-dose distributions in non-modulated proton beams obtained with the FCRS was in good agreement with the depth-dose measurements from the ionization chamber. To evaluate the dosimetric accuracy of the FCRS, the difference of isocenter dose between the delivery dose calculated by the treatment planning system and that measured by the FCRS was within 3%. With in vivo dosimetry using the humanoid phantom, the calculated surface doses overestimated measurements by 4%-8% using FCRS.
Conclusion:In previous study, our results indicate that the performance of the array-type FCRS was comparable to that of the currently used a multi-layer ion chamber system. In this study, we also believe that the fiber-optic Cerenkov radiation sensor has considerable potential for use with in vivo patient proton dosimetry.
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