Fiber-coupled organic plastic scintillator for on-line dose rate monitoring in 6 MV X-ray beam for external radiotherapy

Lars R. Lindvold; A. R. Beierholm; C. E. Andersen

doi:10.1117/12.851346

24 February 2010 Fiber-coupled organic plastic scintillator for on-line dose rate monitoring in 6 MV X-ray beam for external radiotherapy

Lars R. Lindvold, A. R. Beierholm, C. E. Andersen

Author Affiliations +

Proceedings Volume 7559, Optical Fibers and Sensors for Medical Diagnostics and Treatment Applications X; 75590S (2010) https://doi.org/10.1117/12.851346
Event: SPIE BiOS, 2010, San Francisco, California, United States

Abstract

Fiber-coupled organic plastic scintillators enable on-line dose rate monitoring in conjunction with pulsed radiation sources like linear medical accelerators (linacs). The accelerator, however, generates a significant amount of stray ionizing radiation. This radiation excites the long optical fiber (15-20 m), connecting the scintillator, typically with a diameter of 1 mm and 5 mm in length, with the optical detector circuit, causing parasitic luminescence in the optical fiber. In this paper we propose a method for circumventing this problem. The method is based on the use of an organic scintillator, 2-Naphthoic acid, doped in an optical polymer. The organic scintillator possesses a long luminescent lifetime (room temperature phosphorescence). The scintillator is molded onto the distal end of a polymer optical fiber. The luminescent signal from the scintillator is detected by a PMT in photon-counting mode. The long lifetime of the scintillator signal facilitates a temporal gating of the dose rate signal with respect to the parasitic luminescence from the optical fiber. We will present data obtained using a solid water phantom irradiated with 6 MV Xrays from a medical linac at the Copenhagen University Hospital. Also issues pertaining to the selection of proper matrix as well as phosphorescent dye will be presented in this paper.

Citation Download Citation

Lars R. Lindvold, A. R. Beierholm, and C. E. Andersen "Fiber-coupled organic plastic scintillator for on-line dose rate monitoring in 6 MV X-ray beam for external radiotherapy", Proc. SPIE 7559, Optical Fibers and Sensors for Medical Diagnostics and Treatment Applications X, 75590S (24 February 2010); https://doi.org/10.1117/12.851346

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