Search results for "ESR"
showing 10 items of 190 documents
Neutron dosimetry by means of electron spin resonance (ESR) tecnique
2012
Along with the Neutron Capture Therapy (NCT) development and with the use of thermal neutrons for radiotherapeutic purposes, many efforts have been devoted to the beam characterization in order to optimize the therapy procedures. Reliable dosimetric measurements should be able to determine the various components (neutronic and photonic) of the mixed beam usually employed for therapy. We have studied the effect of the additive such as gadolinium and 10B-boric acid on the neutron sensitivity of alanine ESR dosimeters exposed to a gamma and mixed (n, gamma) field mainly composed by thermal neutrons. We have chosen both this additive nuclei because of their very high capture cross section to th…
EPR/alanine dosimetry for two therapeutic proton beams
2016
Abstract In this work the analysis of the electron paramagnetic resonance (EPR) response of alanine pellets exposed to two different clinical proton beams employed for radiotherapy is performed. One beam is characterized by a passive delivery technique and is dedicated to the eyes treatment (OPTIS2 beam line). Alanine pellets were irradiated with a 70 MeV proton beam corresponding to 35 mm range in eye tissue. We investigated how collimators with different sizes and shape used to conform the dose to the planned target volume influence the delivered dose. For this purpose we performed measurements with varying the collimator size (Output Factor) and the results were compared with those obtai…
ESR dosimeter material properties of phenols compound exposed to radiotherapeutic electron beams
2017
Abstract There is a need for a sensitive dosimeter using Electron Spin Resonance spectroscopy for use in medical applications, since non-destructive read-out and dose archival could be achieved with this method. This work reports a systematic ESR investigation of IRGANOX ® 1076 exposed to clinical electron beams produced by a LINAC used for radiation therapy treatments. Recently, dosimetric features of this material were investigated for irradiation with 6 0Co γ -photons and neutrons in both pellet and film shape and have been found promising thanks to their high efficiency of radiation-matter energy transfer and radical stability at room temperature. Here the analysis of the dosimetric fea…
ESR response of watch glasses to proton beams
2010
In this paper we have analyzed the electron spin resonance (ESR) signal of watch glasses irradiated with %60 MeV proton beams in the dose range between 1 and 105 Gy. The composition of samples expressed in oxides weight percentages has been obtained carrying out X-ray fluorescence spectrometry (XRF) mea- surements. The ESR signal has been studied in terms of its dependence on microwave power and modulation field in order to choose the optimal recording parameters. The dependence of the radioinduced signal on the exposure dose has been investigated. A numerical procedure aimed at improving the sensitivity in the low dose range has been developed.
Improvement of ESR dosimetry for thermal neutron beams through the addition of gadolinium.
2007
In this paper, the addition of gadolinium is proposed as a useful tool to enhance the electron spin resonance (ESR) sensitivity of organic compounds to thermal neutrons. The target of this work is the detection, through the ESR technique, of the thermal neutron fluence in a mixed field of photons and neutrons. Gadolinium was chosen because it has a very high capture cross section to thermal neutrons; its nuclear reaction with thermal neutrons induces complex inner shell transitions that generate, besides other particles, Auger electrons, which in turn release their energy in the neighborhood (only several nanometers) of the place of reaction. Gadolinium was added to two organic molecules: a…
First spatial separation of a heavy ion isomeric beam with a multiple-reflection time-of-flight mass spectrometer
2015
Physics letters / B 744, 137 - 141 (2015). doi:10.1016/j.physletb.2015.03.047
Ultraviolet-induced paramagnetic centers and absorption changes in singlemode Ge-doped optical fibers
2009
We investigated the laser-energy-density dependence of absorption changes and paramagnetic centers induced by a cw Ar+ laser operating at 5.1 eV, in both unloaded and H-2-loaded single mode Ge-doped optical fibers. The induced absorption is measured in the blue and near ultraviolet spectral range by using the 3.1 eV photoluminescence, ascribed to Ge lone pair center (GLPC), as an in situ probe source. We find that the Ge (1) center (GeO4-) is induced upon UV exposure by electron trapping on GeO4 precursors, where the free electrons are most likely produced by ionization of GLPC. Ge (1) is responsible of optical transmission loss of the fiber in the investigated range. Hydrogen loading stron…
Hvordan skapes rom for «omvendt deltakelse» i bærekraftig lokal samfunnsutvikling – aksjonsforskningens roller og bevegelser
2021
Det er økende oppmerksomhet på potensialer for borgeres engasjement i bærekraftig omstilling og lokaliseringen av FNs bærekraftsmål. Flere forsknings- og policyrapporter etterlyser bedre forståelse for hvordan bærekraft kan «oversettes» og implementeres i lokal planlegging og handling. Bærekraftig samfunnsomstilling krever bedre forståelser for hvordan offentlige/kommunale systemer kan samarbeide med borgerinitiativer – samtidig som de lokale initiativene bevarer selvstendighet og lokal forankring. I denne artikkelen tar vi utgangspunkt i en aksjonsforskningsprosess med borgerinitiativer i Oslo og ByKuben, Oslo kommunes senter for byøkologi. Vi utforsker hvordan det kan skapes rom for delta…
Alanine/ESR dosimetry for electron Intra-Operative RadioTherapy: output factor measurements and Monte Carlo-GEANT4 simulations for IORT mobile dedica…
2015
Intra-operative radiation therapy (IORT) is a treatment modality where a single high dose of radiation is delivered directly to the tumor bed or to the exposed tumor during the surgical intervention, while avoiding surrounding dose-limiting structures. Mobile electron linear accelerators dedicated to IORT have been manufactured which have promoted a local large diffusion of this radiotherapy modality. For breast irradiation, a single fraction of 21 Gy delivered on the target volume during the surgical procedure is equivalent to the total dosage (60 Gy) usually delivered during 30 external fractionated radiotherapy at 2Gy/fraction. Alternatively, a single dose of 10 Gy can be administered as…