A low-level spectrometer with a planar low-energy HPGe: shielding arrangement tests and system performance for 210Pb determination in air filter samples

A system for low-energy photon spectrometry using a planar germanium detector with appropriate specifications is presented. A spectrometric background investigation has been carried out with various detector shielding arrangements. The characteristics of the system for measurements of 210Pb in air-particulate matter on filters have been determined.

Elementi di progettazione di un bunker per ciclotrone per la produzione di radioisotopi da impiegare in diagnostica PET

Sono riportati i criteri e le metodologie impiegate per la progettazione delle schermature e la predisposizione di dispositivi tecnici di sicurezza in un reparto per la produzione di radiofarmaci per diagnostica PET con impiego di un ciclotrone. Principles and methods for planning of shielding and safety systems in a PET radiopharmaceuticals production center provided with a cyclotron are reported.

The Zero Power Nuclear Reactor AGN-201 “Costanza” as a tool for Higher Education and Research in Nuclear Engineering

The “Zero Power” Nuclear Reactor AGN-201 “Costanza” available at Nuclear Engineering Department of Palermo University is a valuable tool for educational purpose and advanced research. Besides being a useful tool for training of operators, without the time period limits on start-up and shut-down of the larger reactors, it allows the study of all phenomena regarding Nuclear Reactor Physics, Applied Neutronics, Neutron Dosimetry, Nuclear measurements as well as testing of nuclear instrumentation and methods. The experience of work and the obtained results highlight the simplicity of AGN-201 reactor control, its intrinsic safety and its overall versatility in various fields of Nuclear Engineeri…

CRITERI RADIOPROTEZIONISTICI PER LA PROGETTAZIONE, INSTALLAZIONE ED ESERCIZIO DI UN REPARTO PET-CICLOTRONE

La Tomografia con emettitori di positroni (PET) sta acquisendo un ruolo clinico-diagnostico sempre più importante, grazie alla disponibilità di moderni tomografi PET (o PET/CT) e alla produzione di radiofarmaci con ciclotroni compatti e di facile impiego. Le rilevanti problematiche radioprotezionistiche, correlate agli intensi campi di radiazione generati dalle interazioni delle particelle accelerate con i relativi target, trovano una efficace risposta in una stretta collaborazione tra esperti nei diversi settori, sia in fase di progettazione che di installazione del reparto. L’elaborazione e ottimizzazione delle soluzioni progettuali, orientate ad assicurare elevati livelli di sicurezza pe…

Study of background characteristics of a low-level HPGe spectrometer with passive shielding in various configurations

Abstract A low-background germanium spectrometer has been investigated with different combinations of shielding materials in two locations at ground level. In particular, seven shielding configurations have been tested in a room with thick walls and ceiling. The background components, peaks and continuum in the 50–2600 keV energy region, obtained in the several experimental conditions are reported and discussed.

Misure spettrometriche gamma di concentrazioni radionuclidiche in campioni ambientali e alimentari in situazioni di emergenza

Studio di un dosimetro individuale per la misura delle variazioni temporali di intensità di campo magnetico in RM

Application of Electron Spin Resonance technique in neutron dosimetry

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…

Simulazione di un irradiatore gamma con codice Monte Carlo: valutazione della dose e verifica dei contributi strutturali

Si è utilizzato il codice di calcolo Montecarlo MCNP4C per simulare sia le sorgenti che i materiali strutturali dell’irradiatore IGS3, al fine valutarne i loro contributi. Il numero di storie simulate è stato fissato in modo da ottenere un errore casuale abbastanza piccolo. Si sono utilizzati due scenari: uno in presenza del ripiano di appoggio dei campioni da irradiare ed uno senza. I punti dose sono stati posti a tre distanze dalle sorgenti e a tre quote rispetto al piano di appoggio. Negli stessi punti–dose sono state eseguite delle misure sperimentali utilizzando due coppie di sorgenti di radioattive. Sia le simulazioni che i punti sperimentali sono stati messi in relazione con i risult…

Gamma-ray irradiation tests on CCD and CMOS sensors used in imaging techniques

Technologically-enhanced electronic devices are used in various fields as space imaging or diagnostic techniques in medicine. The devices can be exposed to intense radiation fluxes over time which may impair the functioning of the same apparatus, in particular in space applications. In this paper we report the results of a gamma irradiation tests on imaging sensors simulating the space radiation over a long time period. Two types of sensors are taken into consideration: CCD (Charge-Coupled Device) sensors and CMOS based on technology MOS (Metal Oxide semiconductor) used for the realization of transistors widely used in consumer electronics. The devices are supplied by Techno System (Italy),…

Gamma-ray spectrometric measurement of radionuclide purity of radiopharmaceuticals contained in bottle samples

The radionuclide purity of a radiopharmaceutical product is usually measured by gamma-ray spectrometry with various measurement geometries. The importance of this test is that the radionuclide impurities, if present, result in an increase in the radiation dose to the patient without contributing to diagnostic information and in some cases may also interfere with the marking molecules and affect the proper conduct of diagnostic examination. In this work, gamma-ray spectrometry is used to determine the amounts of impurities by adopting as measurement geometry the same bottle containing eluted or prepared radiopharmaceuticals. In addition to high-purity germanium semiconductor detectors, the u…

RADIONUCLIDE CONCENTRATIONS IN AIR PARTICULATE AT PALERMO (ITALY) FOLLOWING FUKUSHIMA ACCIDENT

Following the Fukushima accident, a series of samplings were carried out with a daily frequency to detect the arrival of radioactive contamination in air at Palermo (Italy) and to follow its evolution during the time. Air particulate collection was performed by suction of atmospheric air through cellulose filter paper by means of a high-volume air sampler (∼15 000 m(3) d(-1)). Spectrometric analysis of the filters highlights the presence of (131)I, (134)Cs, (137)Cs and, only for a few samples, traces of (132)Te-(132)I and (136)Cs. Maximum airborne concentrations were 883 μBq m(-3) for (131)I (only particulate), 81 μBq m(-3) for (137)Cs and 70 μBq m(-3) for (134)Cs. From a dose to population…

A Review of Healthcare Failure Mode and Effects Analysis (HFMEA) in Radiotherapy

This paper presents a review of risk analyses in radiotherapy (RT) processes carried out by using Healthcare Failure Mode Effect Analysis (HFMEA) methodology, a qualitative method that proactively identifies risks to patients and corrects medical errors before they occur. This literature review was performed to provide an overview of how to approach the development of HFMEA applications in modern RT procedures, comparing recently published research conducted to support proactive programs to identify risks. On the basis of the reviewed literature, the paper suggests HFMEA shortcomings that need to be addressed.

THERP and HEART integrated methodology for human error assessment

Medical errors are one of the leading causes of death and injury in radiation therapy administration as reported in the literature. This point out an overall deficiency in management allowing patient treatment in the absence of suitable quality assurance processes. Clinical records of major accidental exposure events in radiotherapy show that there is a combination of factors contributing to the accident such as deficient staff training, lack of independent checks, lack of quality control procedures, and absence of overall supervision. Another finding is that training generally addresses only normal situations and does not prepare radiotherapy staff for unusual situations, resulting in a la…

Measurement of 210Pb airborne activity concentration by gamma-ray spectrometry of air particulate samplings

Lead-210 (half-life 22.3 y), is a natural radionuclide, being produced in the atmosphere through radon decay. Due to its affinity for particles, it is rapidly fixed by aerosols and, with its long half-life is the most important tracer of long range atmospheric aerosol transport and removal processes. Main measurement techniques adopted to evaluate 210Pb air activity concentration differ in analysis and sample preparation methods. Some of them involved complex chemical processes or decay product detection (for example 210Po), with a long decay time period between sampling and experimental measurement. The availability of an high-volume particulate sampler (about 900 m3 h-1) combined with a l…

Measurement of air activity concentrations and comparison with meteorological variables in surface air at Palermo , Italy.

ESR response of watch glasses to neutron irradiation

Abstract In this paper we report the results of the electron spin resonance (ESR) study of the radiation-induced signal of watch glasses exposed to neutrons. This work extends the series of analyses of the response of watch glasses to various radiation beams which our research group is carrying out for possible applications in retrospective dosimetry. We have considered fluences up to about 3 × 1011 cm−2. We evaluated the signal fading and we found that in the first hours after exposure the signal rapidly decreases. After about 1000 h, it decreases much more slowly. The signal was reduced by about 25% in about 5 months. The radiation induced signal is found to be linearly dependent on neutr…

A modular neutron irradiator based on 241Am-Be neutron sources

Neutron irradiator facilities with 241Am-Be sources are worldwide used in order to perform neutron activation analysis (NAA), to investigate materials in different research areas or to test and calibrate neutron detectors and environmental or personal dosemeters. The use of a neutron irradiator is advantageous because of its very stable neutron flux, even it is many orders of magnitude lower than the one of a nuclear reactor or a particle accelerator. Most of irradiators are realized with neutron sources located at fixed positions and accordingly the characteristics of neutron spectrum previously assessed do not change. Therefore, an interesting choice is to have a modular facility, capable…

Electron Spin Resonance and Thermoluminescence dating of shells and sediments from Sambaqui (shell mound) Santa Marta II, Brazil

In Tupi, the word Sambaqui means “mound of shells”. These archaeological sites are cultural vestiges left by the prehistoric occupation of the Brazilian coast from five to six thousand years ago. Mollusks, fishes, and other marine edible foods were important for the survival of this population. The remains of foods, mainly shells, were heaped up, giving a mound of different proportions, which became part of the landscape of the Brazilian coastal plain. Due to the large number of Sambaquis in Brazil and considering that Sambaqui Santa Marta II, Laguna, SC, has not yet been dated, Electron Spin Resonance (ESR) measurements were performed in aragonite shells collected from different layers of …

Procedure di preparazione di standards secondari per la determinazione di efficienze di sistemi spettrometrici

Il monitoraggio della radioattività ambientale in Italia: aspetti scientifici, giuridici e normativi. Quaderno No. 1/06, Dipartimento di Ingegneria Nucleare, Università degli Studi di Palermo

Ottimizzazione della protezione di un irradiatore neutronico per test di componenti elettronici

Sono descritte la progettazione e realizzazione di uno schermo mobile per l’irradiatore neutronico Am-Be del Dipartimento DEIM utilizzato per testare la vita media di funzionamento di dispositivi elettronici sottoposti a campi di radiazioni. Il numero di componenti da provare può essere significativamente elevato in relazione all’attendibilità del test e alla statistica dei risultati che si vuole ottenere, con un conseguente incremento della dose all’operatore. Per ridurre il valore di dose-rate totale del campo misto (gamma-neutroni) di radiazione emergente dall’irradiatore si è realizzato uno schermo addizionale di piombo, ferro e acido borico con dimensioni ottimizzate dal punto di vista…

Radiation Protection and Shielding of PET Cyclotron Facilities: Comparison of Theoretical Evaluations and Experimental Evidences

RPN safety analysis to reduce the risk of malpractices in high dose rate brachytherapy

A new fuzzy rule-based assessment model is proposed to evaluate the risk priority number in the Failure Mode, Effects, and Criticality Analysis (FMECA) method to rank component failures and human errors from the medical staff, leading to potential radiological over-exposure of patients during high-dose-rate brachytherapy treatment. The obtained results are relevant for a range of causes that have a reasonable probability of producing significant adverse outcomes. Thus, recommendations are provided for procedures and safety devices to reduce the occurrence of radiological over-exposure accidents. This method can solve the problems in conventional FMECA applications and improve the safety and…

Procedura di calibrazione di sistemi dosimetrici a film radio-cromici GAFCHROMIC® mod. HD-V2

I sistemi dosimetrici a film radiocromici vengono utilizzati nelle misure della dose assorbita da vari materiali sottoposti a radiazioni ionizzanti, nei quali avvengono reazioni chimiche che intensificano le bande ottiche d’assorbanza determinata, quest’ultima, tramite l’utilizzo di uno spettrofotometro. L’impiego di questi sistemi comporta una preliminare calibrazione degli stessi in riferimento a standard internazionali. La dose rilevata fa riferimento generalmente alla dose assorbita in acqua anche se è possibile determinare la stessa in altri materiali tramite opportuni fattori correttivi. L’interesse verso questi sistemi dosimetrici è relativo all’impiego in processi industriali d’irra…

Fission Product Activity Measurements in Air Particulate Filters Collected after Fukushima Accident at Palermo, Italy

In the framework of routine operation of AGN-201 COSTANZA Nuclear research reactor, measurements of radionuclide air concentration are periodically performed by filtering an high volume of air through paper filters and by using HPGe gamma-ray spectrometry. After Fukushima accident, a series of samplings was carried out with a daily frequency so to detect the possible arrival of air radioactive contamination and to follow its evolution. Particulate collection was performed by suction of atmospheric air through 45cm × 45cm Sofiltra-Poelman HYN-75 (Bleu type) cellulose filter paper using a high-volume air sampler located on the roof of our department 20 m above ground-level. The sampling time …

Gamma-ray irradiation tests of CMOS sensors used in imaging techniques

Technologically-enhanced electronic image sensors are used in various fields as diagnostic techniques in medicine or space applications. In the latter case the devices can be exposed to intense radiation fluxes over time which may impair the functioning of the same equipment. In this paper we report the results of gamma-ray irradiation tests on CMOS image sensors simulating the space radiation over a long time period. Gamma-ray irradiation tests were car ried out by means of IGS-3 gamma irradiation facility of Palermo Uni ver sity, based on 60Co sources with dif fer ent ac tiv i ties. To re duce the dose rate and re al ize a nar row gamma-ray beam, a lead-collimation sys tem was pur posely …

Uno studio per l’implementazione della strumentazione della stazione di prelievo di particolato atmosferico del DIN di Palermo

Valutazione dei fattori di correzione per coincidenze–somma in spettrometria gamma di sorgenti volumetriche.

Testing and calibration of ESR response of Fricke gel dosimeters in mixed neutron-gamma fields

Compositi elettroattivi costituiti da nanoparticelle di polianilina disperse in polivinilpirrolidone

EPR/ALANINE PELLETS WITH LOW Gd CONTENT FOR NEUTRON DOSIMETRY

This paper reports on results obtained by electron paramagnetic resonance (EPR) measurements and Monte Carlo (MC) simulation on a blend of alanine added with low content of gadolinium oxide (5 % by weight) to improve the sensitivity to thermal neutron without excessively affecting tissue equivalence. The sensitivity is enhanced by this doping procedure of more an order of magnitude. The results are compared with those obtained with the addition of boric acid (50 % by weight) where boron is in its natural isotopic composition in order to produce low-cost EPR dosemeters. The gadolinium addition influences neutron sensitivity more than the boron addition. The presence of additives does not sub…

DOSIMETRIA DI FASCI NEUTRONICI TRAMITE SPETTROSCOPIA DI RISONANZA PARAMAGNETICA ELETTRONICA (EPR)

Analysis of radionuclide concentration in air released through the stack of a radiopharmaceutical production facility based on a medical cyclotron

Abstract Positron emitting radionuclides are increasingly used in medical diagnostics and the number of radiopharmaceutical production facilities have been estimated to be growing worldwide. During the process of production and/or patient administration of radiopharmaceuticals, an amount of these radionuclides might become airborne and escape into the environment. Therefore, the analysis of radionuclide concentration in the air released to the stack is a very important issue to evaluate the dose to the population living around the plant. To this end, sampling and measurement of radionuclide concentration in air released through the stack of a Nuclear Medicine Center (NMC), provided with a c…

Progettazione di un irradiatore autocontenuto per la calibrazione di dosimetri personali a termoluminescenza

I dosimetri a termoluminescenza utilizzati nel campo della dosimetria personale necessitano – per un loro corretto impiego - di una preventiva fase di calibrazione, realizzata con dose-rate compresi tra 2,5 10-4 mGy/h e 0,01 mGy/h. Per ottenere valori di dose-rate in tale range, si è progettato un irradiatore autocontenuto e autoschermato di piccole dimensioni, utilizzante una sorgente di bassa attività.

Response of GAFChromic® HD-V2 film dosimeter in 10-300 Gy dose range for radiation testing of electronic devices

The study reported in this paper aimed to investigate the response of a GAFChromic? HD-V2 film dosimeter in the dose range between 10 and 300 Gy, normally used to perform irradiation tests on electronic devices with a 60Co gamma-ray irradiator. The well-defined linearity of response in terms of absorbance as a function of absorbed dose, easiness of handling and data analysis of irradiated dosimeters, reproducibility, stability, and insensitivity to visible light and most of the environmental parameters, make HD-V2 film a flexible, inexpensive and reliable dose measurement device. The study has shown a fogging effect of the dosimeter response since its value changes over time. Strategies and…

Una stazione per il monitoraggio on-line di radioattività atmosferica: criteri di progetto e valutazione dei costi

Presso la Sezione di Ingegneria Nucleare del Dipartimento dell’Energia (già Dipartimento di Ingegneria Nucleare, DIN) dell’Università di Palermo, è installato un sistema di aspirazione di particolato atmosferico ad altissimo volume (circa 1000 m3/h di aria). Costruito agli inizi degli anni ottanta del secolo scorso, risulta ormai datato in parte della strumentazione a corredo oltre che nella stessa struttura di protezione dagli agenti atmosferici che lo contiene. La stazione di prelievo è stata utilizzata fino a qualche anno addietro per il monitoraggio giornaliero di deboli concentrazioni di inquinanti radioattivi in aria, con livelli di Minima Attività Rivelabile (MAR) abbastanza ridotti …

Environmental Sample Measurements With Low-background Gamma-ray Spectrometric Systems

MISURE DI RADIOATTIVITA' AMBIENTALE A PALERMO NEL PERIODO 1960 - 2007

Un approccio radiometrico e petrografico per l’analisi di campioni dei monti delle Madonie (Sicilia, Italia)

Una campagna di prelievo nella regione montagnosa delle Madonie (Sicilia) è stata recentemente effettuata per caratterizzare dal punto di vista dosimetrico zone con differenti caratteristiche litologiche. Al termine della campagna sono stati raccolti 41 campioni di terreno e rocce selezionati in base alla loro natura. Tutti i campioni sono stati poi triturati, essiccati e sigillati in beakers "Marinelli" per 20 giorni prima della misura per garantire il raggiungimento dell’equilibrio radioattivo tra 226Ra e 214Bi. Sono stati poi sottoposti a misure spettrometriche gamma con rivelatore a Ge di efficienza 35% per la determinazione delle concentrazioni dei radionuclidi presenti. Le caratterist…

Radiation processing: an alternative and environmentally friendly way to produce advanced Materials. Synthesis of PANI/hydrogels composites

Natural radioactivity in the Alte Madonie Mounts (Sicily, Italy)

With the collaboration of geology experts, we have taken 45 samples of selected soils and rocks. All samples were powdered, dried and sealed in “Marinelli” beakers for 20 days before the measurement so as to ensure that radioactive equilibrium between 226Ra and 214Bi has been reached. Mineralogical and chemical features of the samples were determined by XRD and XRF analysis, instead Gamma ray spectrometric analysis was used in order to quantify radioactivity concentrations. The average values of concentrations of 214Bi, 228Ac and 40K are respectively 30, 19 and 258 Bq/kg while the greatest values were 134, 59 and 748 Bq/kg. A linear relationship exists between 214Bi, 228Ac and 40K activitie…

Coincidence-Summing corrections in high resolution gamma-ray spectrometry: simplified analytical expressions

Simplified expressions to determine the coincidence-summing correction factors by using a matrix representation of a decay scheme are reported. Expressions can be used directly for point sources, with the introduction of full-energy-peak and total efficiencies, while for extended sources a more complex procedure, though approximate, is suggested.

Characterization of Fricke gel dosimeters exposed to gamma rays and neutrons

Measurement of activity of the predominant gamma-emitting radionuclides in activated components of a medical cyclotron plan

An identification and activity evaluation of the predominant gamma-emitting radionuclides in activated parts of a medical cyclotron plant by high resolution gamma-ray spectrometry were performed. The use of LaBr3:Ce scintillation and HPGe detectors was examined in order to solve the measurement problems due to high activity of some components used inside a plant provided with an IBA CYCLONE 18/9 cyclotron. For each component, the identification of some key-radionuclides allows to evaluate the surface dose behaviour as function of decay time. The largest activity values are related to radionuclides with half-life of 70-80 days, while radionuclides with higher half-lives represent less than 1…

Virtual point detector: Application to coincidence-summing correction in gamma-ray spectrometry

The use of an efficiency transfer method based on the virtual point detector approximation to evaluate coincidence-summing correction values for point and volume sources was examined. The method was validated by means of a comparison with experimental efficiency determinations.

Neutron dosimetry by means of electron spin resonance (ESR) tecnique

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…

Risk analysis using fuzzy set theory of accidental exposure of medical staff during brachytherapy procedures

Using fuzzy set theory, this paper presents results from risk analyses that explore potential exposure of medical operators working in a high dose rate brachytherapy irradiation plant. In these analyses, the HEART methodology, a first generation method for human reliability analysis, has been employed to evaluate the probability of human error. This technique has been modified on the basis of fuzzy set concepts to take into account, more directly, the uncertainties of the so-called error-promoting factors on which the method is based. Moreover, with regard to some identified accident scenarios, fuzzy potential dose was also evaluated to estimate the relevant risk. The results also provide s…

Determinazione dell’andamento della componente continua in uno spettro gamma per la valutazione della minima quantità rivelabile

Silicon dosimeters based on Floating Gate Sensor: design, implementation and characterization

A rad-hard monolithic dosimeter has been implemented and characterized in a standard 180 nm CMOS technology. The radiation sensor (C-sensor) is based on a Floating Gate (FG) MOS discharge principle. The output current is processed by a current-to-voltage (I/V) interface and then converted by a 5-bit flash ADC. The dosimeter is re-usable (FG can be recharged) and can detect a dose up to 1krad (Si) with a resolution of 30rad (Si) typical over temperature 0 to 85°C range. The ADC allows easy further signal processing for calibration and averaging, etc. The power consumption of C-sensor plus I/V interface is < 2mW from a 5 V power supply. The overall layout area is less than 0.25mm2. The Rad…

Valutazione della fluenza di neutroni di origine cosmica a livello del suolo

Lo studio degli effetti delle radiazioni neutroniche sul funzionamento dei componenti che fanno parte dei più comuni sistemi elettronici comporta lo studio della fluenza neutronica di origine cosmica a livello del suolo. Infatti la sorgente primaria dei neutroni in atmosfera è principalmente individuabile nell’interazione tra i raggi cosmici di origine solare ed i vari strati dell’atmosfera. Il campo neutronico pertanto non è dunque costante ma dipende fortemente dai cicli di attività solare. In questo lavoro sono presentati i risultati di due cicli di misurazioni del “dose rate” da neutroni nei periodi 21-28 Febbraio e 29 Febbraio-7 Marzo 2012. La strumentazione utilizzata è costituita dal…

Dosimetria a risonanza di spin elettronico (ESR) tramite composti organici (alanina e tartrato di ammonio) per campi misti neutroni-gamma

Esposizione potenziale in impianti di irraggiamento: un’analisi mediante probabilità di tipo sfumato

Dating of marine sediments by using unsupported 210Pb method

In the framework of a more general study on marine species in sediments, it was necessary to obtain a time calibration of the different sections of the sampled sediment columns, both to estimate the pollution of the sediments and, particularly, to study the migration of foraminifers within the column. The method of the unsupported 210Pb, i.e. whose activity is not derived from the radioactive decay of its 226Ra parent, has been used. Since the activity of the supported 210Pb can be determined from the activity of 226Ra, the unsupported 210Pb activity can be calculated as the difference between 210Pb total and 226Ra activities. The unsupported 210Pb decays with its own half-life time, equal …

Sulla determinazione della curva di efficienza per l’analisi spettrometrica gamma di filtri di particolato atmosferico

Uno dei problemi più complessi nella misura con spettrometria gamma di campioni di particolato atmosferico raccolto su filtro è la determinazione, per la geometria di misura adottata, della curva di efficienza fotoelettrica (Full-Energy_Peak Efficiency–FEPE). La geometria di misura che viene presa in considerazione, denominata « packet-sample », dimensioni 6 cm × 6 cm × 0,7 cm, si realizza a partire dal filtro di cellulosa di grandi dimensioni (45 cm x 45 cm) adoperato per il campionamento che, dopo l’aspirazione, viene spruzzato, tagliato, composto e pressato fino a raggiungere le dimensioni indicate per la misura spettrometrica. Le principali difficoltà sono legate alle dimensioni del fil…

I fenoli come nuovi materiali per la dosimetria EPR in campo misto neutroni-gamma

Misure di radioattività ambientale a Palermo: analisi statistica delle concentrazioni in aria di 7Be e 210Pb

In questo lavoro sono presi in considerazione gli andamenti delle concentrazioni in aria di 7Be e, per un più limitato periodo di tempo di 210Pb, e si è proceduto ad una analisi statistica dei dati, prendendo in esame le serie temporali (integrandole per i dati mancanti) dei valori medi mensili e settimanali al fine di operare confronti omogenei con dati disponibili di altre zone geografiche. Sono state studiate le correlazioni fra le serie di dati per i due radionuclidi ed è stata effettuata l’analisi in frequenza al fine di evidenziare ciclicità stagionali. Le analisi effettuate mostrano l’importanza dei processi di trasporto in atmosfera e l’influenza dei parametri meteo-climatici (in pa…

Neutron ESR dosimetry through ammonium tartrate with low Gd content.

This paper continues analyses on organic compounds for application in neutron dosimetry performed through electron spin resonance (ESR). Here, the authors present the results obtained by ESR measurements of a blend of ammonium tartrate dosemeters and gadolinium oxide (5 % by weight). The choice of low amount of Gd is due to the need of improving neutron sensitivity while not significantly influencing tissue equivalence. A study of the effect of gadolinium presence on tissue equivalence was carried out. The experiments show that the neutron sensitivity is enhanced by more than an order of magnitude even with this small additive content. Monte Carlo simulations on the increment of energy rele…

MCNP5 MODELLING OF HPGE DETECTORS FOR EFFICIENCY AND COINCIDENCE SUMMING CORRECTION EVALUATIONS IN GAMMA-RAY SPECTROMETRY.

A modelling of HPGe detectors was performed through simulation with the MCNP5 Monte Carlo code. The simulation results concerning the values of the main physical parameters of the detector are in most cases different from those provided by the manufacturer. The use of “single-line” sources allows us to suitably modify the parameter values used in the detector model. For a detector model, the simulation assesses the distribution of photopeak and total efficiency for point sources, whereas for extended sources a control volume approach allows us to determine elementary efficiency behaviours. An integration of elementary efficiencies over the entire sample volume allows us to evaluate global e…

A procedure to evaluate coincidence-summing correction values in gamma-ray spectrometry with HPGe detectors

The spectrometric analysis of a gamma-emitter sample measured in "close geometry" can be affected by errors due to coincidence-summing effects that can occur when two or more coincident photons (real coincidences) within the resolution time of the spectrometric system are emitted. The probability that these effects occur depends primarily on the nuclide decay scheme, the sample-detector distance and detector intrinsic-efficiency whereas results independent from the sample nuclide activity. Coincidence-summing corrections of the photopeak areas are requested, in particular, when the gamma ray spectrometric analysis is aimed to efficiency or activity determination. In this work is reported a …

Dangerous effects induced on power MOSFETs by terrestrial neutrons: A theoretical study and an empirical approach based on accelerated experimental analysis

This paper investigates the effects that terrestrial neutrons can induce on power MOSFETs when they are biased during their normal working conditions especially in inverters for photovoltaic applications. After a brief review of power MOSFETs failure phenomena caused by neutron irradiation (with emphasis on so called “Single Event Effects” (SEE)), the results of an accelerated test performed with the Am-Be source at the University of Palermo are discussed.

Valutazione della concentrazione in aria di 210Pb mediante misure spettrometriche di campioni di particolato atmosferico

Sono presentati i risultati di una attività di campionamento e misura della concentrazione di 210Pb in aria tramite analisi spettrometrica gamma di campioni di particolato atmosferico raccolto con un aspiratore di elevato volume, senza ricorrere a metodiche di separazione fisico-chimico di difficile realizzazione. I risultati sono messi in correlazione con alcuni parametri meteorologici, potendo determinare una debole correlazione con la temperatura, la quantità di precipitazione su base mensile e con la direzione del vento più che con la sua intensità.

Indicazioni per l’ottimizzazione del sistema di controllo degli effluenti aeriformi in un impianto PET-Ciclotrone

Indoor Fast Neutron Generator for Biophysical and Electronic Applications

This study focuses the attention on an indoor fast neutron generator for biophysical and electronic applications. More specifically, the findings obtained by several simulations with the MCNP Monte Carlo code, necessary for the realization of a shield for indoor measurements, are presented. Furthermore, an evaluation of the neutron spectrum modification caused by the shielding is reported. Fast neutron generators are a valid and interesting available source of neutrons, increasingly employed in a wide range of research fields, such as science and engineering. The employed portable pulsed neutron source is a MP320 Thermo Scientific neutron generator, able to generate 2.5 MeV neutrons with a …

MISURE SPETTROMETRICHE GAMMA DI IMPUREZZE RADIONUCLIDICHE IN PRODOTTI RADIOFARMACEUTICI IMPIEGATI IN MEDICINA NUCLEARE

La recente approvazione e pubblicazione dell’edizione aggiornata della Farmacopea ufficiale (Decreto del 30 marzo 2005) e l’introduzione di requisiti di purezza dei radiofarmaci, ha condotto a sviluppare una serie di studi e di metodiche per la verifica della purezza radionuclidica di un prodotto radioafarmaceutico. Le Norme di buona preparazione di radiofarmaci in Medicina Nucleare individuano alcune procedure di accertamento e di garanzia della qualità di un prodotto tramite l’impiego di una serie di prove predisposte per valutare parametri fisici, chimici, biologici essenziali per la somministrazione in sicurezza a pazienti. La purezza radionuclidica del radiofarmaco è solitamente valuta…

Misura di concentrazioni di prodotti di fissione in aria a Palermo a seguito dell’incidente di Fukushima

Nell’ambito del controllo periodico della radioattività ambientale attorno al reattore di ricerca AGN-201 Costanza di questa Università, vengono effettuate di routine rilevazioni di concentrazioni di radionuclidi artificiali e naturali in atmosfera tramite filtrazioni di aria e misure con spettrometria gamma. Dopo la comunicazione dell’incidente di Fukushima (Giappone), conseguente all’evento sismico del 11 marzo 2011 e del successivo devastante “tsunami”, è stata effettuata una serie di campionamenti di particolato atmosferico con frequenza giornaliera in modo da rilevare l’eventuale arrivo su Palermo (e sulla Sicilia) della possibile contaminazione radioattiva in aria e seguirne l’evoluzi…

THERP and HEART integrated methodology for human error assessment

Abstract THERP and HEART integrated methodology is proposed to investigate accident scenarios that involve operator errors during high-dose-rate (HDR) treatments. The new approach has been modified on the basis of fuzzy set concept with the aim of prioritizing an exhaustive list of erroneous tasks that can lead to patient radiological overexposures. The results allow for the identification of human errors that are necessary to achieve a better understanding of health hazards in the radiotherapy treatment process, so that it can be properly monitored and appropriately managed.

Study of the response of phenol compounds exposed to gamma photons and neutrons for Electron Spin Resonance dosimetry

A Monte Carlo-aided design of a modular 241Am-Be neutron irradiator

Monte Carlo studies aimed at designing a modular 241Am-Be neutron irradiator for testing neutron detectors and personal dosimeters and processing large volume samples are reported in this study. The evaluation of the shapes and thicknesses of the moderator and shielding materials was carried out by a MCNP5 Monte Carlo simulation code. The reliability of the simulation was experimentally verified by the activation of gold foils and TLD dosimeter measurements in an irradiation cell placed at the center of the test configuration.

Applicazione della tecnica HFMEA in radioterapia

Valutazioni di efficienza di rivelatori HPGe con il codice MCNP5

Sono presentate alcune simulazioni con il codice MCNP5 di rivelatori di fotoni di tipo HPGe (High Purity Germanium) per la valutazione di efficienze per alcune geometrie usualmente impiegate in misure di tipo radioprotezionistico (Marinelli beakers, a disco, etc). Il modello del rivelatore è validato mediante confronti con determinazioni sperimentali di sorgenti puntiformi calibrate di tipo “single line”, caratterizzate dalla emissione di un solo fotone gamma per disintegrazione. L’ottimizzazione è realizzata valutando in tutto il range energetico di interesse le differenze tra i valori simulati e sperimentali di efficienza, sia fotoelettrica che totale, al variare di alcuni dei parametri c…

Studi di sicurezza con metodologie ad albero di guasti riguardanti l’esposizione potenziale di un operatore in un reparto di brachiterapia

Analysis of radionuclide concentration in air released through the stack of a radiopharmaceutical production facility

The quantities of positron emitting radionuclides used in medical diagnostics and the number of radiopharmaceutical production facilities have been estimated to be growing worldwide. In this field, an amount of these radionuclides might become airborne and escape into the environment during the process of production and/or during administration by hospital personnel. Therefore, the analysis of dose to the operating staff as well as to the public, due to releases through the stack, is a very important issue. To this end, sampling and measurement of radionuclide concentration in air released through the stack of a Nuclear Medicine Center (NMC), provided with a cyclotron for radiopharmaceutica…

EPR dating of shells from Malhada Marsh, Rio de Janeiro, Brazil

The formation of the coastal plain of the Brazilian sea is mainly due to the fluctuation of relative sea level in the past. Armacao dos Buzios or simply Buzios is a municipality in the microregion of lakes, in the state of Rio de Janeiro. In this region there is a lowland area about two meters above current sea level. This lowland area is also known as coastal plain of Una River. It is expected that during the Holocene period the sea level reached a maximum about 2.5 meters above the current level. During that time billions of mollusks lived and proliferated in the shallow waters around the coastal plain of the Una River. As they died their shells formed a layer in the soil including Malhad…

FMECA Analyses of radiological over-exposure accident to patients in brachytherapy

This paper presents safety analyses of accidental events which can involve patient during High Dose Rate brachytherapy treatment in over-exposures. The study has been performed by using the well-known techniques FMECA modified by Fuzzy logic theory. Moreover, fuzzy HEART methodology was employed in order to evaluate human error probabilities for each treatment stage. The obtained results, aimed to obtain a list of the deviations with a reasonable probability to produce significant adverse outcomes, provided some recommendations for procedures and safety equipments to reduce the occurrence of radiological over-exposure accidents.

Polymer matrices for composites obtained through radiation curing of epoxy resins

Cyclotron –PET/CT: radioprotection aspects, check and tests

Piano di emergenza per il reattore nucleare di ricerca AGN-201 COSTANZA dell’Università di Palermo: presupposti tecnici e valutazioni radiologiche

MCNP5 modelling of HPGe detectors for efficiency evaluation in gamma-ray spectrometry

A modelling of HPGe detectors was performed through simulation with the MCNP5 Monte Carlo code. The simulation results concerning the values of the main physical parameters of the detector are in most cases different from those provided by the manufacturer. The use of “single-line” sources allows us to suitably modify the parameter values used in the detector model. For a detector model, the simulation assesses the distribution of photopeak and total efficiency for point sources, whereas for extended sources a control volume approach allows us to determine elementary efficiency behaviours. An integration of elementary efficiencies over the entire sample volume allows us to evaluate global e…

ESR response of phenol compounds for dosimetry of gamma photon beams

Abstract In the present paper we investigate the features of IRGANOX® 1076 phenols as a material for electron spin resonance (ESR) dosimetry. We experimentally analyzed the ESR response of pellets of IRGANOX® 1076 phenols irradiated with 60Co photons. The best experimental parameters (modulation amplitude and microwave power) for dosimetric applications have been obtained. The dependence of ESR signal as function of γ dose is found to be linear in the dose range studied (12–60 Gy) and the lowest measurable dose is found to be of the order of 1 Gy. The signal after irradiation is very stable in the first thirty days. From the point of view of the tissue equivalence, these materials have mass…

On the thermal-hydraulic performances of the DEMO divertor cassette body cooling circuit equipped with a liner

Abstract In the framework of the Work Package DIV 1 - “Divertor Cassette Design and Integration” of the EUROfusion action, a research campaign has been jointly carried out by University of Palermo and ENEA to investigate the steady-state thermal-hydraulic performances of the DEMO divertor cassette cooling system. The research activity has been focussed onto the most recent design of the Cassette Body (CB) cooling circuit, consistent with the DEMO baseline 2017 and equipped with a liner, whose main function is to protect the underlying vacuum pump CB opening from plasma radiation. The research campaign has been carried out following a theoretical-computational approach based on the finite vo…

Coincidence-summing correction equations in gamma-ray spectrometry with p-type HPGe detectors

Abstract Equations to compute γ−γ and γ−X K coincidence-summing corrections in gamma-ray spectrometry with p-type HPGe detectors are reported. For point sources only full-energy-peak and total efficiencies are needed.

Concentrazioni di gas radon in ambienti lavorativi di diverse regioni italiane

Design and realization of a radon chamber as a secondary standard

The air-radon mixture is the most significant source of natural radiation in workplaces and within dwellings. Despite some uncertainty in the risk estimates, it is widely believed that greater the exposure to radon, greater the risk of developing lung cancer. To assess the radiological hazard, accurate measurements of radon concentrations are necessary. A large variety of radon monitoring instruments have been developed in the last years, usually calibrated in radon chambers containing a known radon concentration released within the chamber by a specific solid radium-226 source. Radon calibration chamber has been constructed to test and calibrate radon and radon progeny detectors at various…

Esposizione potenziale dell’operatore in un impianto dotato di acceleratore: studio mediante l’uso di tecniche ad albero di guasto di tipo sfumato

Design of Am-Be neutron irradiator by Monte Carlo simulation

Neutron irradiator facilities with Am-Be sources are worldwide available in order to perform neutron activation analysis (NAA), to investigate materials in different research areas or to test and calibrate neutron detectors and dosemeters. The use of a neutron irradiator is advantageous because have a very stable neutron flux, even it is many orders of magnitude lower than the one of a nuclear reactor or a particle accelerator. Many of irradiators are realized with neutron sources located at fixed positions and accordingly the characteristics of neutron spectrum previously assessed do not change [1]. However, an interesting chance is to have a modular facility, capable of varying conditions…

Studio e calibrazione della risposta ottica ed NMR di dosimetri gel di tipo Fricke (FXG) in campi misti neutroni-gamma per applicazioni cliniche

Confronti dosimetrici tra due tecniche radioterapiche a modulazione di intensità nei trattamenti stereotassici polmonari ipofrazionati

La radioterapia stereotassica extra-cranica (Stereotactic Body Radiation Therapy) consente di somministrare una dose ablativa ad un volume bersaglio non encefalico mediante un numero ridotto di frazioni. La riduzione nel numero di frazioni comporta necessariamente un aumento della precisione ed accuratezza in tutte le fasi del trattamento, dalla simulazione CT alla pianificazione ed all’erogazione della dose terapeutica. Dal punto di vista dosimetrico i trattamenti SBRT sono caratterizzati innanzitutto da un elevato grado di conformazione e soprattutto dalla presenza di gradienti di dose particolarmente ripidi necessari per minimizzare la dose ai tessuti sani circostanti ed agli organi a ri…

Experiences of radioactivity measurement in various environmental samples

An overview on our activity of environmental radioactivity measurement is reported. Radionuclide concentration have been evaluated in the particulate air, soils and rocks, drinking and surface water, wastewater, marine sediments and so on. Most of radionuclide concentration evaluation were performed using facilities of DEIM Department of Palermo University. In particular, particulate collection was performed by suction of atmospheric air through 45x45 Sofiltra-Poelman HYN-75 (Bleu type) cellulose filter paper using a high-volume air sampler located on the roof of our department building (20 m above ground-level), located within an undisturbed large park area in the city of Palermo (latitude…

Measurement of radionuclide activities induced in target components of an IBA CYCLONE 18/9 by gamma-ray spectrometry with HPGe and LaBr3: Ce detectors.

Cyclotrons are used worldwide to produce radiopharmaceuticals by proton irradiation of a suitable target. The intense secondary neutron beam generated by proton interactions with the target induce high radionuclide activities in the target assembly parts that may result in an exposure to high dose levels of the operators during maintenance. The main goal of this work is to evaluate gamma-emitting radionuclide activities induced in Havar foils and titanium windows of a target assembly and carousel stripper forks of an IBA CYCLONE 18/9 cyclotron. The knowledge of radionuclide inventory for each component is required by many companies to assess risk for operators before waste handling and disp…

Environmental Radioactivity Measurements in the Mediterranean Area

In the framework of an environmental radioactivity monitoring program, a research activity concerning an optimization of techniques for sampling and measurement of environmental radioactivity was performed at the Nuclear Engineering Department (DIN) of Palermo University. Al-though initially aimed to the analysis of monitoring data of the local network installed at the nuclear research reactor AGN-201 "COSTANZA" of Palermo University, in the following years the studies were oriented to improve the sampling facilities and measurement systems with the aim to achieve also detection limits as low as possible. The activity has allowed to collect numerous data of nuclide activity concentration fo…

Analisi statistica delle concentrazioni in aria di 7Be e 210Pb misurate a Palermo.

Vengono analizzati e discussi i risultati delle misure, effettuate con cadenza quasi giornaliera, delle concentrazioni in aria a Palermo di 7Be (1982-2005) e 210Pb (1995-2005). In particolare è esaminato l’andamento dei rapporti di attività dei due radionuclidi relativamente al periodo di disponibilità congiunta dei dati al fine di evidenziare possibili correlazioni tra i due radionuclidi e con i dati meteo-climatici locali. Il 7Be (tempo di dimezzamento 53,29 giorni) è il prodotto dell’interazione dei raggi cosmici con nuclei di azoto ed ossigeno. La sua origine cosmogenica rende le concentrazioni misurate fortemente dipendenti dalla posizione geografica e dai cicli stagionali. Esso emette…

Neutron and gamma-ray radiation fields characterisation in a 241Am–Be irradiator in view of its use as research testing tool

Abstract A neutron irradiation facility based on four 241Am–Be sources, each one with an activity of 111 GBq, placed in Plexiglas pipes inside a tank filled with water used both as a moderator and a biological shielding, has been realized at the Engineering Department of Palermo University. In view of its use as a testing tool in various research activities, a characterisation of the irradiator has been carried out through the determination of neutron and gamma-ray flux profiles, the evaluation of the thermal to total neutron flux percentage ratio and of the epithermal neutron shaping factor. To this aim, results of a Monte Carlo (MCNP5 code) simulation based on a previously validated sourc…

Gestione di un impianto ciclotronico e controlli periodici di sicurezza

Equivalent detector models for the simulation of efficiency response of an HPGe detector with PENELOPE code

In this work, some ‘equivalent’ models for the simulation of efficiency response of a High-Purity Germanium (HPGe) detector, installed inside a ‘low background’ bunker in the Engineering Department of the University of Palermo, were developed. The main feature was to attribute the uncertainties of the model to only one of the parameters, the dead layer of the detector, keeping unchanged the other data provided by the manufacturer. With this technique, using the Monte Carlo PENELOPE code in the 2011 version, the efficiency response was evaluated and compared with the previous one performed with MCNP5 code. The validation of equivalent models is performed by comparing the simulation results w…

Room-Temperature X-ray response of cadmium-zinc-Telluride pixel detectors grown by the vertical Bridgman technique

In this work, the spectroscopic performances of new cadmium–zinc–telluride (CZT) pixel detectors recently developed at IMEM-CNR of Parma (Italy) are presented. Sub-millimetre arrays with pixel pitch less than 500 µm, based on boron oxide encapsulated vertical Bridgman grown CZT crystals, were fabricated. Excellent room-temperature performance characterizes the detectors even at high-bias-voltage operation (9000 V cm−1), with energy resolutions (FWHM) of 4% (0.9 keV), 1.7% (1 keV) and 1.3% (1.6 keV) at 22.1, 59.5 and 122.1 keV, respectively. Charge-sharing investigations were performed with both uncollimated and collimated synchrotron X-ray beams with particular attention to the mitigation o…

Education and Research in Nuclear Engineering and Radiological Protection at Nuclear Engineering Department of Palermo University

A radiometric and petrographic interpretation of discrepancies on uranium content in samples collected at Alte Madonie Mounts region (Sicily, Italy)

Abstract The main goal of this work is to evaluate a correlation between anomalous Uranium (U) content and petrographic features of some soil and rock samples collected at Alte Madonie Mounts region (North-central Sicily, Italy). A total of 41 samples of selected soils and rocks were collected, powdered, dried and sealed in “Marinelli” beakers for 20 days before the measurement to ensure that radioactive equilibrium between 226 Ra and 214 Bi was reached. Gamma-ray spectrometric analysis was used to quantify radioactivity concentrations. Mineralogical and chemical features of the samples were determined by X-ray Fluorescence (XRF), X-ray Diffractometry (XRD), Attenuated Total Reflection-Four…

Numerical expressions for the computation of coincidence-summing correction factors in γ-ray spectrometry with HPGe detectors

Numerical expressions to compute gamma-gamma and gamma-X(K) coincidence summing corrections were deduced by using a suitable computer program and a matrix representation of a decay scheme. For point sources only full-energy peak and total efficiencies are needed. Alternatively, values of peak-to-total ratio can be introduced. For extended sources, the same expressions can be considered with the introduction of "effective efficiencies". Examples of the use of the expressions for point sources and a particulate filter sample measured with a 60% relative efficiency HPGe detector are reported.

SAFETY ANALYSES OF POTENTIAL EXPOSURE IN MEDICAL IRRADIATION PLANTS BY FUZZY FAULT TREE

EVALUATION OF GAMMA-RAY AND NEUTRON FLUXES IN A NEUTRON IRRADIATOR USED FOR RAD-HARD ELECTRONIC COMPONENTS TESTING

An irradiator with four Am-Be neutron sources (activity 111 GBq each) was used for testing electronic RAD-HARD components developed for space application [1]. For this goal, an essential requirement to be met is the knowledge with sufficient precision of neutron and gamma-ray fluxes in the irradiation channel where the components are put for the test. For this goal, an experimental measurement activity was started to validate also Monte Carlo simulation results, obtained with application of MCNP5 code. As regards gamma-ray flux, we considered separately two gamma-ray contributions: the first one, at 60 keV energy, associated with the decay of the 241Am, and the second one, at 2.2 MeV, due t…

Dating of a sediment core in the Palermo Bay (Sicily, Italy)

An extensive study of sediment cores in the Palermo Bay has been carried during the last two years. Main goal of the research was to study the environmental pollution of the area, using foraminifers as an environmental indicator.

Valutazione della dose potenziale per alcuni scenari incidentali in un impianto HDR: uso di tecniche di tipo sfumato

Procedura di calibrazione di un set di Dosimetri TLD secondo la ISO/ASTM51956:2005(E) e la ASTM standard E-668

La misura della dose assorbita da dosimetri passivi, a seguito della loro esposizione a radiazioni ionizzanti, è una procedura fondamentale per valutare gli effetti indotti da tali radiazioni nell’ambito della dosimetria ambientale. Per effettuare delle corrette valutazioni, è stato selezionato un set di dosimetri a termoluminescenza (TLD) scelti, tra un’ampia gamma di tipologie di dosimetri a nostra disposizione, come i più idonei a fornire misure di dose attendibili (nelle prescritte condizioni di funzionamento). Tali dosimetri sono stati sottoposti ad una specifica procedura di irraggiamento e successiva lettura, allo scopo di realizzare un’opportuna calibrazione nel rispetto di quanto p…

A Training Experience of Operators with the AGN-201 “Costanza” Research Reactor of Palermo University

The nuclear reactor AGN-201 named “Costanza”, installed at the Nuclear Engineering Section of the Department of Energy of the University of Palermo, is a “zero power” research reactor designed to be mainly used for education purposes as well as for research applications, such as activation analysis and irradiation tests, and last, but not the least, for radionuclide production to be used in nuclear medical applications. Due to its intrinsic safety and low margin of reactivity (less than 350 p.c.m.) so as to the absence of start-up and shut-down time limits, it represents a useful training tool for operators, too. This paper reports some of the activities carried out within the framework of …

Sintesi di materiali avanzati mediante radiazioni ionizzanti

Fogging effect correction of Gafchromic HD-V2 film response for its use in high-dose radiotherapy

GAFChromic® HD-V2 film is a reliable dose measurement device, thin, flexible, inexpensive, simple to use and easy to analyze. The response in terms of net absorbance with respect to absorbed dose was found to be linear in a large dose range, which supports the feasibility of using the film dosimeters in many applications, such as radiotherapy. For its use, a "fogging" effect must be take into account since film response changes with time. To determine a calibration curve valid for any time, fogging effect was investigated for more than 400 days. A correction procedure allows the use of HD-V2 film dosimeters in high-dose radiotheraphy, as brachytherapy, and quality assurance (QA) procedures.

On the AGN - 201 "COSTANZA" Research Reactor at the Department of Nuclear Engineering of the University of Palermo

UN IRRADIATORE NEUTRONICO MODULARE CON SORGENTI DI 241Am-Be PER IL TEST DI DOSIMETRI NEUTRONICI PERSONALI

Irradiatori neutronici basati su sorgenti radionuclidiche sono impiegati in diversi paesi per l’analisi per attivazione di vari campioni, per studiare le caratteristiche dei materiali sottoposti a irradiazione, ma anche per studiare la risposta di rivelatori e/o dosimetri personali sensibili alla componente neutronica. Per quest’ultima applicazione, l’uso di un irradiatore con sorgenti risulta molto vantaggioso per la stabilità nel tempo del flusso neutronico, mentre è relativamente poco importante il valore assoluto del flusso neutronico, di qualche ordine di grandezza inferiore a quello di reattori o di acceleratori di particelle. Per l’effettuazione di test su rivelatori e/o dosimetri pe…

NMR relaxometry measurements of Fricke gel dosimeters exposed to neutrons

Fricke infused gel matrices offer several features making them suitable for dosimetric applications; among the set here are tissue equivalence, low cost and ease of preparation. Their nuclear magnetic resonance (NMR) relaxation properties can be used as a radiation detector for the dosimetry of beams used in cancer therapy. In recent years neutron capture therapy has been resumed for the treatment of various types of cancer and it requires three-dimensional mapping of the neutron fields. In this work, we investigated this particular application through NMR relaxometry and MR imaging of Fricke gels exposed to neutrons. We analyzed both the R1 and R2 relaxation rates, which relate to the long…

Spettrometria gamma su una barra di combustibile del Reattore AGN-201 Costanza

Analisi di sicurezza nella procedura di protonterapia oculare applicata presso i Laboratori del Sud dell’INFN di Catania

A partire dal 2002, l’Azienda Ospedaliera Universitaria “Policlinico Vittorio Emanuele” di Catania ha effettuato il trattamento di circa 350 pazienti affetti da neoplasie oculari mediante fasci di protoni prodotti con il ciclotrone disponibile presso i Laboratori nazionali del Sud (LNS). Tale impianto viene utilizzato per attività di ricerca nell’ambito della fisica sperimentale, per cui è stato necessario modificare le caratteristiche del fascio, rendendolo idoneo alle applicazioni cliniche. Il lavoro di ricerca ha riguardato lo svolgimento della analisi del rischio volto ad individuare possibili fallimenti nelle procedure adottate per il trattamento del paziente sottoposto a cicli di prot…

Valutazione sperimentale delle componenti del campo di radiazioni in un irradiatore neutronico con sorgenti 241Am-Be e confronto con simulazioni Monte Carlo

Il presente lavoro riguarda la valutazione sperimentale delle componenti gamma e neutronica del campo di radiazioni presente in diversi punti all’interno del canale di irraggiamento di un irradiatore neutronico con sorgenti 241Am-Be. Per la componente gamma sono stati considerati due contributi: il primo associato a gamma di energia di 60 keV, dovuto al decadimento dell'241Am; il secondo a gamma di energia 2,2 MeV, dovuto alla cattura radiativa dei neutroni da parte dello schermo biologico (acqua) che circonda le sorgenti. Per le misure sperimentali sono stati utilizzati dosimetri tipo TLD700 in due diverse configurazioni: TLD "nudi" per misura della dose relativa al campo gamma totale e TL…

Radiation Protection Evaluations about PET Cyclotrons

Progettazione e realizzazione di un irradiatore neutronico modulare basato su sorgenti Am-Be

Irradiatori neutronici basati su sorgenti radionuclidiche sono impiegati in diversi paesi per studiare le caratteristiche dei materiali sottoposti a irradiazione e/o la risposta di rivelatori e/o dosimetri personali sensibili alla componente neutronica. Per quest’ultima applicazione, l’uso di un irradiatore con sorgenti radionuclidiche risulta molto vantaggioso per la stabilità nel tempo del flusso neutronico, mentre è relativamente poco importante il valore assoluto del flusso neutronico, che può anche essere di qualche ordine di grandezza inferiore a quello di reattori o di acceleratori di particelle. Per l’effettuazione di test su rivelatori e/o dosimetri personali neutronici risulta mol…

Novel epoxy formulations for high energy radiation curable composites

Abstract It has been widely recognised that high energy radiation can be effectively applied to the cure of epoxy resins in applications as composite matrices or structural adhesives with improvements in product quality and/or reduction in production costs. In the presence of suitable initiators, polymerisation of epoxies occurs via cationic mechanism, thus restricting the choice of the resin system components to species which do not contain electron donor groups. The present investigation is aimed to identify suitable co-monomers to be formulated with an epoxy resin, resulting in different cure reaction kinetics and application properties of the cured resin. In particular, four different a…

Misura della concentrazione di Radon in diverse sedi lavorative distribuite sul territorio nazionale

Analisi di sicurezza mediante l’uso di tecniche ad albero di guasto di tipo sfumato riguardanti l’errata esposizione ad alto rateo di dose di un paziente in brachiterapia

Caratterizzazione ESR di composti fenolici: nuovi materiali per la dosimetria in campo misto neutroni-gamma

Radiation protection evaluations about a radiopharmaceutical production center based on a cyclotron

Positron Emission Tomography (PET) has became a worldwide used functional and molecular imaging technique. Most of PET (or PET/CT- Computed Tomography) diagnostic facilities are installed within large population cities as well as dimensions of modern medical cyclotrons allow to install them inside hospitals or other health centers. Therefore, special radiation protection evaluations to assure safety operational conditions to operators and population are required. This work is focused on training activities oriented to evaluate PET/Cyclotron radiation protection procedures or to study special safety systems. The students are particularly oriented to determine shielding thickness according to…

Preliminary design of the top cap of DEMO Water-Cooled Lithium Lead breeding blanket segments

Abstract Within the framework of EUROfusion R&D activity, a research campaign has been carried out at the University of Palermo, in close cooperation with ENEA labs, in order to preliminary design the top cap foreseen for the DEMO Water-Cooled Lithium Lead (WCLL) breeding blanket segments. Due to the high heat and pressure loads acting on such component, its design results particularly demanding and a specific multi-physics approach is needed, covering several aspects from thermal-hydraulics to structural assessments. Preliminary detailed CAD model of the cap integrated into the upper region of the WCLL breeding blanket outboard central segment has been set-up, equipped with proper cooling …

Fuzzy modelling of HEART methodology: application in safety analyses of accidental exposure in irradiation plants

The present paper refers to the obtained results by using Fuzzy Fault Tree analyses of accidental scenarios which entail the potential exposure of operators working in irradiation industrial plants. For these analyses the HEART methodology, a first generation of the Human Reliability Analysis method, has been employed to evaluate the probability of human erroneous actions. This technique has been modified by us on the basis of fuzzy set concept to more directly take into account the uncertainties of the so called error-promoting factors, on which the method is grounded. The results allow also to provide some recommendations on procedures and safety equipments to reduce the radiological expo…

La camera Radon del Dipartimento di ingegneria Nucleare dell'Università di Palermo

OTTIMIZZAZIONE DI SISTEMI DI RADIOPROTEZIONE IN UN REPARTO PER LA PRODUZIONE DI RADIOFARMACI PER DIAGNOSTICA P.E.T.

In questo lavoro è riportata l’attività di verifica della realizzazione e ottimizzazione delle tecniche, dei dispositivi di protezione e delle procedure operative adottate in un moderno impianto di Diagnostica PET, dotato di ciclotrone per la produzione di radiofarmaci con accelerazione di protoni fino a 16,5 MeV di energia. Con riferimento alla realizzazione di un insediamento all’interno di una Azienda Ospedaliera della città di Palermo, inserita in un contesto cittadino, una analisi approfondita dei sistemi di sicurezza insieme alla identificazione di alcune criticità ha consentito di riconsiderare alcuni dispositivi, anche alla luce di più moderne tecnologie, e di riesaminare l’effettiv…

Sulla misura della concentrazione in aria di 210Pb tramite spettrometria gamma di particolato atmosferico raccolto su filtro

CONCENTRATION MEASUREMENTS OF 7Be AT GROUND LEVEL AIR AT PALERMO, ITALY- COMPARISON WITH SOLAR ACTIVITY OVER A PERIOD OF 21 YEARS

Air activity concentrations of (7)Be in Palermo determined for the period January 1995-December 2002 by gamma-ray spectrometric analysis of particulate samples collected on paper filter by a high-volume sampler (approximately 900 m(3) h(-1)) are reported. The temporal behaviour of (7)Be concentration presents the same characteristics already observed in the measurements carried out over the previous 13-year (1982-1994) investigated period. The mean value of 5.06 mBq m(-3) obtained from the analysis of the 4636 particulate samples collected from 1982 to 2002 can be considered a representative value of (7)Be air concentration at ground level in our geographical zone. The comparison of long-te…

A chamber to test the response of radon detectors to changing environmental conditions.

Radon risk assessment is carried out with accurate measurements with active or passive instrumentation. All radon detectors must be calibrated and tested using a radon chamber containing a known concentration of radon produced by specific sources of 226Ra. Some of the chambers can also be used to test the response of detectors as a function of environmental conditions. In this case, it can be inferred a calibration curve with respect to changing of the parameter considered. For this aim, a new chamber radon was designed and realized to perform both calibration of instruments and to study the detector response in a large range of variation of the environmental parameters (pressure, 700 - 110…

Sulla ottimizzazione dei sistemi di sicurezza in un impianto per la produzione di radiofarmaci con ciclotrone

Il numero di impianti per la produzione di radiofarmaci con ciclotrone è in continuo aumento, grazie alla disponibilità sul mercato di macchine acceleratrici con costi accessibili e di facile installazione e impiego. Un aspetto non secondario, per un utilizzo sicuro di tali impianti, riguarda la predisposizione di sistemi di sicurezza, attiva e passiva, per la tutela dei lavoratori e della popolazione anche verso possibili incidenti. E’ interessante ed attuale lo studio di ottimizzazione dei sistemi di sicurezza sia per una più efficace logica di intervento e prevenzione, sia per tenere conto delle nuove possibilità di realizzazione consentite dai progressi tecnologici. Nel presente lavoro …

Search for Neutrons as Evidence of Cold Fusion

In this paper investigations performed at the University of Palermo in an attempt to reproduce the cold fusion experiment are reported. The search was devoted to detecting neutron emission from palladium electrodes electrolytically charged with deuterium. In no test was neutron emission significantly over the background observed, either in bursts or continuous. Results of a few tests are reported. For the more sensitive test, an upper limit for D(d,n) cold fusion (at 98% confidence level) of {lambda}{sub f} {lt} 3.6 {times} 10{sup {minus}24} fusion/s {center dot} d-d pair is determined.

Determination of 210Pb concentration in the air at ground-level by gamma-ray spectrometry

Abstract 210 Pb activity concentrations in the air of Palermo were determined by γ-ray spectrometric analysis of 323 particulate samples collected in the period September 1995–December 1996. For each sample, the air filtered through a cellulose filter paper was 8600 m 3 on average. The values of the daily activity concentration of 210 Pb were ranging from 136 to 3390 μBq/m 3 .

Sui metodi di misura spettrometrica gamma della purezza radionuclidica in alcuni radiofarmaci

Le recenti “Norme di buona preparazione di Radiofarmaci in Medicina Nucleare”, allegate all’approvazione e pubblicazione del I supplemento dell’edizione aggiornata della Farmacopea ufficiale (Decreto del 30 marzo 2005[1]), hanno introdotto alcune procedure di accertamento di requisiti di purezza e di garanzia della qualità di un prodotto radiofarmaceutico. Di particolare interesse è la valutazione della purezza radionuclidica di un radiofarmaco solitamente effettuata tramite misure spettrometriche gamma. In questo lavoro saranno esaminate alcune metodiche spettrometriche gamma utili alla corretta determinazione delle piccole quantità di impurezze presenti in un radiofarmaco. I campioni pres…

Uno studio per l’implementazione della strumentazione della stazione di prelievo di particolato atmosferico del DIN di Palermo

Dangerous Effects Induced on Power MOSFETs by Terrestrial Neutrons

This paper investigates the effects that terrestrial neutrons can induce on power MOSFETs when they are biased during their normal working conditions especially in inverters for photovoltaic applications. After a brief review of power MOSFETs failure phenomena caused by neutron irradiation (with emphasis on so called “Single Event Effects” (SEE)), the results of an accelerated test performed with the Am-Be source at the University of Palermo are discussed.

Installazione di un sistema tomografico Ibrido SPET-CT in un reparto di Medicina Nucleare: Valutazioni dosimetriche e di Radioprotezione

Evaluation Of 210Pb Air Activity Concentration By Direct Gamma Ray Spectrometry Of Air Particulate Samplings.

A radiometric and petrographic approach to risk assessment at Alte Madonie Mounts region (Sicily, Italy)

The main goal of this work was to assess the radiological hazard at Alte Madonie Mounts region (north-central Sicily, Italy) in response to rumours of an increase in the incidence of cancer in this area. A correlation between the natural radionuclide contents and the petrographic features of the soil and rock samples was also evaluated. A total of 41 samples of selected soils and rocks were collected, powdered, dried and sealed in 'Marinelli' beakers for 20 d prior to measurement to ensure that a radioactive equilibrium between (226)Ra and (214)Bi had been reached. A gamma-ray spectrometer was used to quantify the radioactivity concentrations. To determine (238)U and (232)Th activities, the…

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

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…

An experimental approach to efficiency calibration for gamma-ray spectrometric analysis of large air particulate filters

Abstract A full-energy-peak efficiency (FEPE) calibration procedure for gamma-ray spectrometric analysis of air particulate samples collected on large filters is described herein. The experimental results are obtained for an unconventional measurement geometry, termed a “packet-sample”. The sample is obtained from a large cellulose filter (45 cm×45 cm) used to collect air particulate samples that is resized to dimensions suitable for spectrometric measurements (6 cm×6 cm×0.7 cm). To determine the FEPEs, many standards were created, i.e., some filters containing a small amount of ThO 2 and others containing a known amount of KCl. Efficiency curves obtained through best fits to experimental d…

Analysis of Air Discharges from a PET Radiopharmaceuticals Production Center Based on a Cyclotron

The control of air contamination in a Nuclear Medicine Center (NMC) provided with a cyclotron for the production of radiopharmaceuticals is based on an automatic systems for air sampling and measurements. An important control for the assessment of dose to the population is aimed at the measurement of air concentration of stack release and inside the cyclotron vault during irradiation. The frequency of sampling can be setup as continuous with respect to the stack effluent release and cyclic for other work environments. The gamma-ray spectrometric measurement are made on-line and for a short time by using a shielded Marinelli beaker filled with sampled air and a gamma detector. The use of thi…

Passive safety systems in view of sustainable development

Measurement of 7Be and 210Pb air activity concentrations and comparison with meteorological variables in surface air at Palermo, Italy

Impiego di un sistema spettrometrico gamma portatile basato su uno scintillatore LaBr3(Ce)

La risoluzione energetica di uno scintillatore LaBr3(Ce) è decisamente superiore (<3% a 662 keV) rispetto a quella di un più tradizionale scintillatore NaI(Tl) anche se ancora decisamente non comparabile con quella dei rivelatori a Ge. Questa caratteristica del rivelatore, oltre il ridotto tempo di risposta, lo rende adatto per misure “in situ” specialmente quando è importante l’individuazione rapida in uno spettro gamma di manifestazioni fotoelettriche con energia molto prossime tra loro (individuazione di sorgenti o rifiuti radioattivi, misure nel campo delle salvaguardie nucleari, …). Una significativa limitazione nel suo impiego è tuttavia rappresentata dalla elevata radioattività intri…

Attivita’ di misura delle concentrazioni di radionuclidi naturali gamma-emittenti nel particolato atmosferico a Palermo

Gamma-ray spectrometyric characterization of waste activated target components in a PET Cyclotron

Datazione di eventi incidentali mediante spettrometria gamma di campioni ambientali

La datazione di un evento incidentale di tipo nucleare costituisce un elemento importante per la valutazione delle implicazioni dosimetriche e di protezione ambientale correlate all’evento. Può risultare utile disporre di una procedura di valutazione del “tempo di raffreddamento” di un evento incidentale tramite prelievo e misura di campioni ambientali. Una procedura di datazione tramite misura spettrometrica delle attività di prodotti di fissione è stata proposta in [1,2], applicata a un piccolo campione di uranio irradiato per breve tempo in un reattore nucleare. In questo lavoro viene verificata l’applicabilità della metodica in varie situazioni ed è analizzata la possibilità di estender…

Studies on the AGN - 201 "COSTANZA" Research Reactor

Thermoluminescence response of sodalime glass irradiated with proton and neutron beams

In the research field of emergency dosimeters to be used in case of accidental radiation exposure of the population, watch glass has been considered as a possible fortuitous dosimetric material. This paper reports on results obtained by thermoluminescence of glass samples exposed to neutron and proton beams. Thermoluminescent glow curves have been analyzed for each irradiation studying the modifications induced by the irradiation as a function of proton dose or neutron fluence. The glow curve in a specific temperature range has been used as dosimetric parameter. The thermoluminescence response of samples exposed to protons has been found to be linear in the dose range between 2 and 20 Gy an…

Piani di Sicurezza per il trasferimento di sorgenti di radiazioni gamma e neutroni ad alta attività

La movimentazione di sorgenti ad alta attività, sia che si tratti dell’acquisizione, trasporto e collocazione di nuove sorgenti in impianti di irraggiamento, o del trasferimento di sorgenti all’interno della stessa struttura, deve essere pianificata nei minimi dettagli con un piano di lavoro. Ciò è fondamentale per l’analisi di tipo radioprotezionistico ma anche dal punto di vista della valutazione dei rischi di altra natura, non ultima la movimentazione dei carichi. Tale analisi preventiva viene effettuata avvalendosi sinergicamente di un gruppo di esperti con diverse competenze e varie figure di responsabilità (Responsabile delle sorgenti, RSPP, Esperto Qualificato, Medico Autorizzato, …)…

Analysis of 7Be and 210Pb concentration and 7Be/210Pb activity ratio in ground level air in Palermo (Italy)

A series of measurements of particulate samples collected on paper filters in Palermo (Italy) during 1995–2005 has been performed to detect 210Pb air activity concentration and, along with previous similar data on 7Be, to evaluate their activity ratio. Average values for the daily activity concentrations of 7Be and 210Pb are found to be 4.7 and 0.6 mBq/m3 , respectively, 9.8 being the average activity ratio. Data confirm a seasonal behavior for both radionuclides. A correlation between 7Be and 210Pb air activity concentrations seems to exist, despite their different origins. The time behaviors of both 7Be and 210Pb air concentrations and 7Be/ 210Pb activity ratio have been compared with som…

Application of Monte Carlo simulation to design a modular 241Am-Be neutron irradiator

Most of neutron irradiators are realized with neutron sources located at fixed positions and accordingly the characteristics of neutron spectrum previously assessed do not change. However, an interesting chance is to have a modular facility, capable of varying conditions of irradiation and setting the prevalence of fast or thermal neutron spectrum components. In this work we report the Monte Carlo studies devoted to design a modular 241Am-Be neutron irradiator making use of different moderators (water, graphite, polyethylene and so on) in order to obtain a neutron energy distribution useful to test neutron detectors or personal dosemeters. The optimization of thicknesses and shape of the mo…

PROVE ED ESPERIMENTI DI VERIFICA DELLA SICUREZZA DEL REATTORE NUCLEARE DI RICERCA AGN-201 “COSTANZA”

The “Zero Power” Nuclear Reactor AGN-201 “Costanza” available at Nuclear Engineering Department of Palermo University is a valuable tool for educational purpose and research. Besides being a useful tool for training of operators, without the time period limits on start-up and shut-down of the larger reactors, it allows the study of some phenomena regarding nuclear reactor physics, applied neutronics, neutron dosimetry, nuclear measurements as well as testing of nuclear instrumentation and methods. The experience of work and the obtained results highlight the simplicity of AGN-201 reactor control, its intrinsic safety and its overall versatility in various fields of Nuclear Engineering.

Le facilities di irraggiamento del DEIM per il testing di componenti rad-hard

Il Dipartimento Energia, Ingegneria dell’Informazione e Modelli Matematici dell’Università degli Studi di Palermo (DEIM), ospita due facility di irraggiamento impiegate per attività di didattica, sperimentale e di ricerca: • Impianto di irraggiamento Gamma Sicilia 3 (IGS-3); Irradiatore neutronico Am-Be. In questa monografia sono presentate le caratteristiche dei due impianti di irraggiamento insieme alle proprietà di interazione delle radiazioni con la materia, con particolare riferimento agli effetti sui componenti elettronici.

A venti anni da Chernobyl : andamento delle concentrazioni di 137Cs in aria e analisi retrospettiva delle misure di radioattivita’ ambientale a Palermo

Phenol compounds for Electron Spin Resonance dosimetry of gamma and neutron beams

Monitoraggio campi elettromagnetici: dalla teoria alla pratica - caso studio di utilizzazione contemporanea di apparecchiature dichiarate conformi dal fabbricante

Maintenance Operation on AGN-201 “COSTANZA” Nuclear Research Reactor of Palermo University

During operations with AGN-201 “COSTANZA” nuclear research reactor of Palermo University a failure of a compensated boron-lined ionization chamber provided with a measurement channel was highlighted. A maintenance program aimed to verify the operative conditions of all measurement systems was then started. It was easy to identify as cause of the malfunction a seepage of water inside the container of a Westinghouse WL 6377 ion chamber due to a lack of watertight closure. This can be attributed to corrosion of the container due to parasitic currents circulating between the container, the chamber and the reactor tank that acts as electrical ground of the system. In this work we refer over main…

Recent advances in the development of high-resolution 3D cadmium-zinc-telluride drift strip detectors.

In the last two decades, great efforts have been made in the development of 3D cadmium–zinc–telluride (CZT) detectors operating at room temperature for gamma-ray spectroscopic imaging. This work presents the spectroscopic performance of new high-resolution CZT drift strip detectors, recently developed at IMEM-CNR of Parma (Italy) in collaboration with due2lab (Italy). The detectors (19.4 mm × 19.4 mm × 6 mm) are organized into collecting anode strips (pitch of 1.6 mm) and drift strips (pitch of 0.4 mm) which are negatively biased to optimize electron charge collection. The cathode is divided into strips orthogonal to the anode strips with a pitch of 2 mm. Dedicated pulse processing analysis…