Multichannel Dosimeter and $\alpha$-Al$_{2}$O$_{3}$:C Optically Stimulated Luminescence (OSL) Fiber Sensors for Use in Radiation Therapy—Evaluation With Photon Beams

Sylvain Magne (1) , Loïc de Carlan (2) , Jean-Marc Bordy (2) , Aurélie Isambert (3) , André Bridier (3) , Pierre Ferdinand (1)

1 LCFO - Laboratoire Capteurs Fibres Optiques
2 LNHB - Laboratoire National Henri Becquerel
3 IGR - Institut Gustave Roussy

A multichannel OSL fiber optic dosimeter based on optically stimulated luminescence (OSL) of alumina is proposed for online in vivo dosimetry (IVD) in radiation therapy (RT). Two types of dosimetric-grade Al$_2$ O$_3$ : C crystals are compared and show different behavior according to manufacturing process. Metrological validations have been performed with a Saturne 43 LINAC in reference conditions at CEA LIST LNHB (French Ionizing Radiation Reference Laboratory). The dose response of OSL integrals under photon beam irradiation (6, 12, and 20 MV) show sublinearity behavior modeled by second-order equations and exhibit a small energy dependence (between 0.7% and 1.4%), explained by a modified intermediate cavity model adapted to a LINAC photon spectrum. Preclinical tests at Institut Gustave Roussy (IGR) prove that a proper design for a PMMA build-up cap leads to a low dependence vs photon beam orientation ($\pm$1.5% and $\pm$0.9%) and vs field size in view of surface measurements.

Keywords: Optical Fiber Sensor (OFS); radiotherapy; Optically Stimulated Luminescence (OSL); alumina; Index Terms—In Vivo Dosimetry (IVD); carbon; fibre optic sensors; dosimetry; linear accelerators; radiation therapy; Photonics; Crystals; Optical fiber sensors; Optical fibers; α-Al2O3:C; optically stimulated luminescence fiber sensors; multichannel OSL fiber optic dosimeter; online in vivo dosimetry; manufacturing process; metrological validations; Saturne 43 LINAC; CEA LIST LNHB; French ionizing radiation reference laboratory; photon beam irradiation; second-order equations; modified intermediate cavity model; LINAC photon spectrum; photon beam orientation; surface measurements; voltage 6 MV to 20 MV; Al2O3:C

Domains: Instrumentation and Detectors [physics.ins-det]; Optics / Photonic; Medical Physics [physics.med-ph]; Nuclear Experiment [nucl-ex]

Sylvain Magne, Loïc de Carlan, Jean-Marc Bordy, Aurélie Isambert, André Bridier, et al.. Multichannel Dosimeter and $\alpha$-Al$_{2}$O$_{3}$:C Optically Stimulated Luminescence (OSL) Fiber Sensors for Use in Radiation Therapy—Evaluation With Photon Beams. IEEE Transactions on Nuclear Science, 2011, 58 (2), pp.386 - 394. ⟨10.1109/TNS.2011.2114369⟩. ⟨cea-01840719⟩