Presenter of 1 Presentation
INORGANIC SCINTILLATORS FOR FLASH-IORT DOSIMETRY: DEVELOPMENT AND TEST OF A LYSO DETECTOR PROTOTYPE
Abstract
Background and Aims
Fast and accurate active dosimeters are the key component to perform quantitative measurements in FLASH radiotherapy. No reference active dosimeters are currently available since most detectors show non recoverable saturation effects for dose-per-pulse (DPP) values typical of FLASH (1Gy/p or higher). Aim of this study is to develop and test a detector prototype based on inorganic scintillators for FLASH-IORT active dosimetry.
Methods
The detector prototype is composed of a LYSO scintillating crystal (2x2x10 mm^3) wrapped in 5 Teflon layers and coupled to an optical fiber 1.2 m long (0.980 mm diameter, PMMA core). The other end of the fiber is connected to a Photodiode (PD, Thorlabs - SM05PD7A) read out by a multimeter (Keithley 617) that integrates the PD photocurrent. The detector was placed in a PMMA support and covered with solid water slabs. The phantom was irradiated with a 7 MeV IORT electron LINAC (NOVAC7 from SIT, Aprilia, Italy) at different SSDs and depths in solid water to vary DPP at the detector position. The DPP spanned from conventional (3 cGy/pulse) to FLASH values (250 cGy/pulse). The DPP was evaluated by means of calibrated Gafchromic films.
Results
The PD integrated charge was linear in the whole range of DPP values explored and 0.46 nC/Gy in sensitivity was measured.
Conclusions
Further measurements are planned to fully characterize the detector such as extend the DPP upper limit and investigate the dependency on the instantaneous DPP, but these first results indicate LYSO based detectors as promising candidates for FLASH-IORT active dosimetry.
Author Of 1 Presentation
INORGANIC SCINTILLATORS FOR FLASH-IORT DOSIMETRY: DEVELOPMENT AND TEST OF A LYSO DETECTOR PROTOTYPE
Abstract
Background and Aims
Fast and accurate active dosimeters are the key component to perform quantitative measurements in FLASH radiotherapy. No reference active dosimeters are currently available since most detectors show non recoverable saturation effects for dose-per-pulse (DPP) values typical of FLASH (1Gy/p or higher). Aim of this study is to develop and test a detector prototype based on inorganic scintillators for FLASH-IORT active dosimetry.
Methods
The detector prototype is composed of a LYSO scintillating crystal (2x2x10 mm^3) wrapped in 5 Teflon layers and coupled to an optical fiber 1.2 m long (0.980 mm diameter, PMMA core). The other end of the fiber is connected to a Photodiode (PD, Thorlabs - SM05PD7A) read out by a multimeter (Keithley 617) that integrates the PD photocurrent. The detector was placed in a PMMA support and covered with solid water slabs. The phantom was irradiated with a 7 MeV IORT electron LINAC (NOVAC7 from SIT, Aprilia, Italy) at different SSDs and depths in solid water to vary DPP at the detector position. The DPP spanned from conventional (3 cGy/pulse) to FLASH values (250 cGy/pulse). The DPP was evaluated by means of calibrated Gafchromic films.
Results
The PD integrated charge was linear in the whole range of DPP values explored and 0.46 nC/Gy in sensitivity was measured.
Conclusions
Further measurements are planned to fully characterize the detector such as extend the DPP upper limit and investigate the dependency on the instantaneous DPP, but these first results indicate LYSO based detectors as promising candidates for FLASH-IORT active dosimetry.