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Study of Signal Filtering of a Dosimetry System with a Luminescent Plastic Detector, Designed for Dosimetry in Radiotherapy, by Means Spectral Analysis

L Nunez1*, (1) Universidad Autonoma de Madrid, Madrid, ES


(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: study the procedure of preserve signal produced in a luminescent polymer transducer used for radiotherapy dosimetry where the light signal is transmitted by the two optical fiber device.

Methods: system developed for the measurement of XR and electron radiotherapeutic beams, consists of two attached optical fibers of PMMA, 20 meters in length and 1.0 mm in diameter, one of which is coupled to a polymer scintillator as transducer element or detector; the other fiber is used to quantify and subtract the undesirable signal generated in the irradiation process, where part of the transmission fiber is inevitably irradiated.
Irradiation was performed with 6, 10 and 15 MV RX and 6 and 15 MeV electron beams( LINACs Varian TrueBeam and SIEMENS PRIMUS, using a plastic plate phantom and an AvaSpec-ULS4096CL-EVO spectrophotometer. Irradiation was carried out with different energies, field sizes, dose rates (with and without flattening filter in XR) and depths, to observe the influence of the different energy spectra originated with these conditions, on each of two optical fibers with transducer element and without it.

Results: detector assembly is quantitatively sensitive to the changes associated with the different dose rates and conditions.
The spectra were identical for all irradiations performed, with the significant response in the range between 380 and 520 nm, with a maximum peak at 430 nm. It also highlights the coincidence of a peak at 450 nm in both fibers and a spectral matching outside the mentioned range.

Conclusion: coincidence of the spectrum outside the range mentioned and the peak at 450 nm, justifies the strategy of using a second fiber without detector to obtain isolated the signal originated in the detector.


Not Applicable / None Entered.


TH- Radiation Dose Measurement Devices: Development (new technology and techniques)

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