With the increasing complexity of dose patterns external beam radiotherapy, there is a great need for new types of dosimeters. We studied the first prototype of a new dosimeter array consisting of water-equivalent plastic scintillating fibers for dose measurement in external beam radiotherapy. We found that this array allows precise, rapid dose evaluation of small photon fields. Starting with a dosimeter system constructed with a single scintillating fiber coupled to a clear optical fiber and read using a charge coupled devicecamera, we looked at the dosimeter’sspatial resolution under small radiation fields and angular dependence. Afterward, we analyzed the camera’s light collection to determine the maximum array size that could be built. Finally, we developed a prototype made of ten scintillating fiber detectors to study the behavior and precision of this system in simple dosimetric situations. The scintillation detector showed no measurable angular dependence. Comparison of the scintillation detector and a small-volume ion chamber showed agreement except for and fields where the output factor measured by the scintillator was higher. The actual field of view of the camera could accept more than 4000 scintillating fiber detectors simultaneously. Evaluation of the dose profile and depth dose curve using a prototype with ten scintillating fiber detectors showed precise, rapid dose evaluation even with placement of more than 75 optical fibers in the field to simulate what would happen in a larger array. We concluded that this scintillating fiber dosimeter array is a valuable tool for dose measurement in external beam radiotherapy. It possesses the qualities necessary to evaluate small and irregular fields with various incident angles such as those encountered in intensity-modulated radiotherapy, radiosurgery, and tomotherapy.
This work has been supported by the Collaborative Health Research Projects Grant No. 312799 from the Natural Sciences and Engineering Research Council (NSERC) and the Canadian Institutes of Health Research. L. A. acknowledges an NSERC scholarship and was supported in part by the Odyssey program and the Houston Endowment, Inc. Award for Scientific Achievement at The University of Texas M. D. Anderson Cancer Center.
II. MATERIALS AND METHODS
II.A. Dosimeter components and operation principles
II.B. Data acquisition and processing
II.C. Spatial resolution and angular dependence of a single detector
II.D. Characterization of the FOV and light spots
II.E. Dosimeter array prototype
III.A. Spatial resolution and angular dependence of a single detector
III.B. Characterization of the FOV and light spots
III.C. Dosimeter array prototype
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