Search results for "Dosimetry"
showing 10 items of 297 documents
Comparison of EPR response of alanine and Gd2O3-alanine dosimeters exposed to TRIGA Mainz reactor.
2015
In this work we report some preliminary results regarding the analysis of electron paramagnetic resonance (EPR) response of alanine pellets and alanine pellets added with gadolinium used for dosimetry at the TRIGA research reactor in Mainz, Germany. Two set-ups were evaluated: irradiation inside PMMA phantom and irradiation inside boric acid phantom. We observed that the presence of Gd2O3 inside alanine pellets increases the EPR signal by a factor of 3.45 and 1.24 in case of PMMA and boric acid phantoms, respectively. We can conclude that in the case of neutron beam with a predominant thermal neutron component the addition of gadolinium oxide can significantly improve neutron sensitivity of…
Artificial intelligence for image-guided prostate brachytherapy procedures
2020
Radiotherapy procedures aim at exposing cancer cells to ionizing radiation. Permanently implanting radioactive sources near to the cancer cells is a typical technique to cure early-stage prostate cancer. It involves image acquisition of the patient, delineating the target volumes and organs at risk on different medical images, treatment planning, image-guided radioactive seed delivery, and post-implant evaluation. Artificial intelligence-based medical image analysis can benefit radiotherapy procedures. It can help to facilitate and improve the efficiency of the procedures by automatically segmenting target organs and extrapolating clinically relevant information. However, manual delineation…
Monte Carlo simulation of the response of ESR dosimeters added with gadolinium exposed to thermal, epithermal and fast neutrons
2009
Abstract Monte Carlo numerical calculations of the response of alanine and ammonium tartrate ESR (electron spin resonance) dosimeters exposed to neutron fields with different energy spectra are reported. Results have been obtained for various gadolinium concentrations inside the dosimeters. Furthermore, in order to simulate the in-phantom response we have carried out calculations by varying the depth of the dosimeter. We have found that a large enhancement is obtained for thermal neutrons, because of the very high capture cross section of gadolinium to thermal neutrons. A good enhancement was obtained for epithermal neutrons, whereas the sensitivity improvement in the case of fast neutron i…
The alanine detector in BNCT dosimetry: Dose response in thermal and epithermal neutron fields
2014
Purpose: The response of alanine solid state dosimeters to ionizing radiation strongly depends on particle type and energy. Due to nuclear interactions, neutron fields usually also consist of secondary particles such as photons and protons of diverse energies. Various experiments have been carried out in three different neutron beams to explore the alanine dose response behavior and to validate model predictions. Additionally, application in medical neutron fields for boron neutron capture therapy is discussed. Methods: Alanine detectors have been irradiated in the thermal neutron field of the research reactor TRIGA Mainz, Germany, in five experimental conditions, generating different secon…
DOSIMETRIA ESR CON ALANINA PER ADRONTERAPIA CON IONI CARBONIO
2015
La sicurezza del paziente sottoposto a trattamenti terapeutici con radiazioni ionizzanti e il buon esito degli ultimi sono strettamente legati all’ottimizzazione delle procedure di esposizione alle radiazioni ionizzanti. In particolare è fondamentale arrecare il danno minore possibile ai tessuti sani che circondano la neoplasia da trattare. Rispetto ai campi di radiazione convenzionali utilizzati in radioterapia (fotoni), le particelle cariche pesanti (protoni e ioni carbonio) offrono diversi vantaggi quali la bassa dispersione laterale, l’alta efficacia biologica (RBE) nella regione del picco di Bragg ed un profilo di dose caratteristico in profondità del tutto differente da quello dei fot…
A dosimetric study of Leipzig applicators.
2005
Purpose: To obtain the absolute dose-rate distribution in liquid water for all six cup-shaped Leipzig applicators by means of an experimentally validated Monte Carlo (MC) code. These six applicators were used in high-dose-rate (HDR) afterloaders with the “classic” and v2 192Ir sources. The applicators have an inner diameter of 1, 2, and 3 cm, with the source traveling parallel or perpendicular to the contact surface. Methods and materials: The MC GEANT4 code was used to obtain the dose-rate distribution in liquid water for the six applicators and the two HDR source models. To normalize the applicator output factors, a MC simulation for the “classic” and v2 sources in air was performed to es…
SU-E-J-64: Evaluation of a Commercial EPID-Based in Vivo Dosimetric System in the Presence of Lung Tissue Heterogeneity
2014
Purpose: To study the performance of Dosimetry Check (DC), an EPID-based dosimetry software, which allows performing transit dosimetry, in low density medium, by comparing calculations in-phantom, and analysing results for 15 lung patients. Methods: DC software (v.3.8, pencil beam-based algorithm) has been tested, for plans (Eclipse v.10.0 TPS) delivered in two Varian Clinac iX equipped with aS1000 EPIDs.In the CIRS lung phantom, comparisons between DC and Eclipse (Acuros) were performed for several plans: (1) four field box; (2) square field delivered in arc mode; (3) RapidArc lung patient plan medially centred; (4) RapidArc lung patient plan centred in one lung. Reference points analysed:…
Aluminium nitrate ceramics: a potential UV dosemeter material.
2002
The ceramic material AlN-Y 2 O 3 is proposed as a potential ultraviolet radiation (UVR) dosemeter using optically stimulated luminescence (OSL) and thermally stimulated luminescence (TL). Experimental studies have shown that AlN ceramics exhibit attractive characteristics suitable for practical UV dosimetry applications. The features are: (1) the spectral sensitivity covers the 200-350 nm range, in the UV-B region it is similar to that of human skin; (2) the angular dependence of the incident radiation follows the cosine law; (3) high yields of both UVR-induced OSL and TL signals compared to those of Al 2 O 3 :C; and (4) a large dynamic range TL signal (5 orders of magnitude). Although ther…
SU-E-T-176: Commissiong and Initial Clinical Experience with Dosimetry Check, a Commercial Software for in Vivo Volumetric Dosimetry
2013
Purpose: The aim of this work is to study the differences of reference point doses between the commercial EPID based dosimetry software Dosimetry Check (DC) and TPS to establish an accuracy level of the system, to evaluate its use in clinical routine and to obtain results for the first patients. Methods: We used DC v.3.8 (Math Resolutions), two Varian Clinac iX accelerators equipped with EPID aS1000 and Eclipse v.10.0 with AAA algorithm. Several plans with and without air gap were generated over the phantoms: MP1 Water Tank and Solid Octavius 4D (PTW). 5 head and neck, 3 lung and 4 prostate cases were selected for clinical evaluation. We compared the calculated dose at the isocenter and in …
Monte Carlo Application in Brachytherapy Dosimetry
2009
This paper devoted to Monte-Carlo Applications in BT Dosimetry is organized in four parts: 1. Motivation of the use of Monte Carlo in brachytherapy 2. The use of Monte Carlo to obtain dose distribution around brachytherapy sources 3. Experimental dosimetry versus Monte Carlo 4. Others Monte Carlo applications in brachytherapy