Search results for " DOSIMETRY"

Electron Spin Resonance dosimetry using organic compounds (alanine and ammonium tartrate) for mixed neutron-gamma fields

2016

Alongside with the development of Neutron Capture Therapy (NCT) and the use of thermal neutrons for radiotherapeutic purposes, many efforts have been devoted to the characterization of the beam in order to optimize therapy procedures. Reliable dose measurements should be able to determine the various (neutrons and photonic) components of the mixed beam usually employed for therapy. This paper studies the effect of additives such as boric and gadolinium nuclei on the sensitivity of neutron organic (alanine and ammonium tartrate) dosimeters analyzed through Electron Spin Resonance (ESR) technique (Marrale, 2014). These dosimeters were exposed to a mixed (neutron-gamma) field mainly composed o…

ESR response of alanine films exposed to low-energy (1-40 keV) X-rays

2018

Introduction L-a-alanine has aroused considerable interest for use in radiation ESR dosimetry. In this work, we examined the energy response of alanine ESR films in the low energy X-photon energy range between 1 keV and 40 keV. Dose measurements through a reference ionization chamber and a semiconductor detection system were also performed to complement ESR measurements. Methods Commercial alanine ESR films were used. All ESR signal measurements were also done using an XBand (9.7 GHz) Bruker spectrometer. The dosimeters were irradiated at the "Livio Scarsi" Laboratory (LAX) of the University of Palermo, where X-ray beams in the 1–40 keV energy range are produced using a Seifert SN60 tube. R…

The role of Electron Spin Resonance (ESR) spectroscopy in dosimetric and dating applications

2010

The use of gadolinium for ESR dosimetry

2010

The application of gadolinium to sensitize Electron Spin Resonance (ESR) dosimeters is reviewed. This nucleus is chosen because it has very good features in interacting with ionizing radiations. In particular, it has a very high capture cross section for thermal neutrons which favors the interactions of these particles within the detector; moreover, the charged secondary particles released after neutron interactions (mainly Auger and internal conversion electrons) are able to release their energy close the gadolinium site and, therefore, inside the sensitive volume of the detector. Consequently, the addition of gadolinium inside ESR dosimeters produces a significant enhancement of thermal n…

Monte Carlo simulation of energy absorbed in phenolic ESR dosimeters added with gadolinium exposed to thermal, epithermal and fast neutrons

2017

Abstract In this work analyses of the energy released per unit mass in phenolic compound exposed to neutron beams were performed with the aim of predicting the increase in dose achievable by addition of gadolinium (Gd) inside the pellets. In particular, Monte Carlo (MC) simulations were carried out for IRGANOX® 1076 phenolic compound irradiated with neutron beams with different energy spectra at various depths inside a water phantom. The addition of gadolinium increases sensitivity of phenolic ESR (electron spin resonance) dosimeters to neutrons thanks to the high gadolinium cross section for neutron capture and to the large number of secondary particles (mainly Auger and internal conversio…

Application of Electron Spin Resonance technique in neutron dosimetry

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 [1]. 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 t…

EPR DOSIMETRY INTERCOMPARISON USING SMART PHONE TOUCH SCREEN

2014

This paper presents the results of an interlaboratory comparison of retrospective dosimetry using the electron paramagnetic resonance method. The test material used in this exercise was glass coming from the touch screens of smart phones that might be used as fortuitous dosimeters in a large-scale radiological incident.

GEL DOSIMETERS FOR RADIOTHERAPY APPLICATIONS: RESULTS OF A “RESEARCH PROJECT OF NATIONAL INTEREST” (PRIN)

2016

Introduction: Gel dosimeters for three-dimensional mapping of radiotherapy doses were introduced at Yale University in the mid-1980’s. Soon after, research and development in this field also started in Italy. Early work was done at the Istituto Superiore di Sanità and at the Universities of Pisa and Milan. Several institutes now collaborate on this topic with the goal of developing new formulations of hydrogel matrices with improved characteristics of stability, sensitivity and spatial resolution compared to those of earlier Fricke-gel and polymer-gel systems. Materials and methods: Contrary to earlier gels based on natural gelling agents, such as porcine skin gelatin and/or agarose, which …

First Characterization of Novel Silicon Carbide Detectors with Ultra-High Dose Rate Electron Beams for FLASH Radiotherapy

2023

Ultra-high dose rate (UHDR) beams for FLASH radiotherapy present significant dosimetric challenges. Although novel approaches for decreasing or correcting ion recombination in ionization chambers are being proposed, applicability of ionimetric dosimetry to UHDR beams is still under investigation. Solid-state sensors have been recently investigated as a valuable alternative for real-time measurements, especially for relative dosimetry and beam monitoring. Among them, Silicon Carbide (SiC) represents a very promising candidate, compromising between the maturity of Silicon and the robustness of diamond. Its features allow for large area sensors and high electric fields, required to avoid ion r…

Radiation leakage study for the Valencia applicators

2011

Abstract Introduction and purpose The Valencia applicators which are accessories of the microSelectron-HDR afterloader (Nucletron, Veenendaal, The Netherlands) are designed to treat skin lesions. These cup-shaped applicators are an alternative to superficial/orthovoltage x-ray treatment units. They limit the irradiation to the required area using tungsten-alloy shielding, and are equipped with a tungsten-alloy flattering filter allowing the treatment of skin tumors, the oral cavity, vaginal cuff, etc. The tungsten-alloy thickness to shield radiation is not the same in all parts of the applicators. This fact led us to question whether the leakage radiation differs depending on where it is me…