Search

In the framework of the ORAMED project (Optimization of RAdiation protection for MEDical staff), funded by the European Union Seventh Framework Programme, different studies were aimed at improving the quality of radiation protection in interventional radiology and nuclear medicine. The main results of the project were presented during a final workshop held in Barcelona in January 2011, the proceedings of which are available in the open literature. One of the ORAMED tasks was focused on the problem of eye-lens photon exposure of the medical staff, a topic that gained more importance especially after the ICRP decision to lower the limiting equivalent dose to 20 mSv per year. The present technical note has the scope, besides briefly summarising the physical reasons of the proposal and the practical implications, to provide, in tabular form, a set of air kerma to Hp(3) conversion coefficients based on the adoption of a theoretical cylindrical model that is well suited for reproduction of the mass and the shape of a human head. © The Author 2012. Published by Oxford University Press. All rights reserved.

In the framework of the ORAMED project (Optimization of RAdiation protection for MEDical staff), funded by the European Union Seventh Framework Programme, different studies were aimed at improving the quality of radiation protection in interventional radiology and nuclear medicine. The main results of the project were presented during a final workshop held in Barcelona in January 2011, the proceedings of which are available in the open literature. One of the ORAMED tasks was focused on the problem of eye-lens photon exposure of the medical staff, a topic that gained more importance especially after the ICRP decision to lower the limiting equivalent dose to 20 mSv per year. The present technical note has the scope, besides briefly summarising the physical reasons of the proposal and the practical implications, to provide, in tabular form, a set of air kerma to Hp(3) conversion coefficients based on the adoption of a theoretical cylindrical model that is well suited for reproduction of the mass and the shape of a human head.

An experimental campaign was conducted to assess the neutron dose field inside the biological shield of the PETrace cyclotron at the S. Orsola-Malpighi hospital in Bologna. The results of the survey were analyzed to confirm that neutrons are emitted isotropically, thus validating the hypothesis of nuclear evaporation, as opposed to cascade, as the dominant mechanism for neutron emission.

The report describes the methods that are necessary to manage the quality of ionizing-radiation measurements and calibrations. These methods are applicable to all types of radiation that are currently used in medical physics, radiation protection, industrial applications, and environmental measurements. The types of radiation covered include photons, electrons, neutrons, and charged particles. Quantities considered include absorbed dose, air kerma, fluence, and dose equivalent.The report is intended for individuals and organizations responsible for calibrations and measurements of ionizing radiation. It is also expected to be of interest to agencies responsible for regulating radiological activities. The information and guidance provided should be useful to personnel making radiation measurements as well as to the users of calibration services. The report discusses methods for establishing and maintaining a measurement quality assurance program.

Following the publication of the EU Council Directive 96/29, EURADOS coordinated two working groups (WGs) for promoting the process of harmonisation on individual monitoring of occupationally exposed persons in Europe. An overview of the major findings of the second WG is presented. Information on the technical and quality standards and on the accreditation and approval procedures has been compiled. The catalogue of dosimetric services has been updated and extended. An overview of national regulations and standards for protection from radon and other natural sources in workplaces has been made, attempting to combine the results from individual monitoring for external, internal and workplace monitoring. A first status description of the active personal dosemeters, including legislative and technical information, and their implementation has been made. The importance of practical factors on the uncertainty in the dose measurement has been estimated. Even if a big progress has been made towards harmonisation, there is still work to be done.

A large number of standards are available for radiation protection and individual monitoring purposes. They are published by various organisations, international and national. Moreover, the increasing policy of 'Quality' applied to individual monitoring requires the implementation of standards on Quality Assurance (QA) both in technical and management aspects of a dosimetric service. Implementation of standards is not mandatory; therefore, varying degrees of implementation can be found in different European countries. However, for a number of good reasons, a degree of harmonisation within the European Union (EU) of the requirements and procedures for individual monitoring would be desirable. Harmonisation as applied to dosimetric services does not mean that they should all follow exactly the same procedures, but that they should aim to meet the same general requirements, and their results should be comparable. This article aims to compile information on the use of all standards applied within individual monitoring practices, be it on the calibration of dosemeters or on the QA procedures to be applied to the overall dose evaluation process. Both 'technical standards' and 'quality standards' will be discussed. A list of documents of relevance to subjects such as recommendations and requirements in the field of individual monitoring, whose application could help in the harmonisation of procedures, will also be given. As it is agreed that implementation of quality standards is a relevant framework within which harmonisation can be achieved, guidance on the implementation of quality standards in a dosimetric service is given. Accreditation and approval of dosimetric services will be of relevance in the process of harmonisation of individual monitoring within the EU. In this article, a discussion of various procedures and the meaning of both forms of recognition is also provided. Although most of the text applies to the monitoring of internal and external exposure to ionising radiation, the emphasis of this practical guidance is on monitoring for external radiation with passive dosemeters.

Il dosimetro per neutroni veloci, attualmente in uso presso il Servizio di Dosimetria Personale dell'Istituto di Radioprotezione dell'ENEA, è costituito da un rivelatore a tracce di PADC (polyallyl-diglicol-carbonate), commercialmente denominato CR-39, prodotto dalla ditta Intercast Europe S.p.A. di Parma. Gli studi effettuati, sia sulla composizione chimica del materiale che sulle modalità di trattamento dello stesso nel corso degli ultimi anni, finalizzati al miglioramento delle caratteristiche dosimetriche (sensibilità, segnale di fondo, soglia di rivelazione, dipendenza della risposta dall'energia dei neutroni incidenti), hanno condotto alla scelta di rivelatore di CR-39 addizionato con 0,1 % di DOP (Dioctylphthalate).Una volta stabilita la composizione ottimale del materiale, è stato necessario però attuare una procedura di test di accettazione di una partita di rivelatori. Nel caso del CR39, ciò significa effettuare un test su campioni di rivelatori appartenenti a ciascuna lastra di un gruppo di lastre appartenenti allo stesso ciclo di produzione. A questo scopo sono stati stabilite le procedure del test di controllo sulla intera partita ed i criteri di accettabilità. Sono presentati i risultati dei test su partite relative a diversi anni di produzione.In collaborazione con la Intercast Europe S.p.A., è stato inoltre avviato uno studio allo scopo di valutare quali parametri legati al ciclo di produzione influenzano, e in che misura, la qualità del materiale. Diversi fattori del processo di produzione, infatti, quali la zona di iniezione della miscela nello stampo, la posizione della lastra e la non uniformità del calore all'interno del forno, possono essere causa della possibile disomogeneità CR-39 e comprometterne le prestazioni dosimetriche. Nel presente lavoro sono presentati i risultati del test di accettazione effettuato su di una intera lastra di materiale prodotto nel 2003 (circa 1000 rivelatori). I risultati ottenuti hanno permesso di verificare le procedure di controllo di qualità esistenti (tempistica, dimensione e modalità scelta campioni) e convalidare i criteri di accettabilità.Gli studi effettuati hanno confermato l'importanza dei test di accettazione del materiale di rivelazione ai fini di assicurare all'utente una migliore qualità ed affidabilità del servizio di dosimetria fornito.

Il Servizio di Dosimetria dell'Istituto di Radioprotezione dell'ENEA fornisce, da circa vent'anni, dosimetri di CR-39 per la dosimetria dei neutroni veloci.L'esperienza sviluppata in questi anni nelle tecniche di sviluppo e lettura dei rivelatori, ha permesso successivi miglioramenti delle procedure utilizzate ai fini di una maggiore accuratezza ed efficienza.Il presente lavoro si propone di illustrare l' implementazione di un sistema di lettura automatico per dosimetri di CR-39 per neutroni veloci, recentemente sviluppato e realizzato all'Istituto di radioprotezione dell 'ENEA, nella routine del Servizio Dosimetrico. Il nuovo sistema, basato su di un software di Visione automatica della National Instruments, oltre a rendere più rapida e riproducibile la procedura di lettura, permette di migliorare la valutazione delle dosi in termini di accuratezza e di prestazioni nel campo delle basse dosi. Il sistema è dotato, sia di algoritmi di analisi geometrica delle tracce, sia di algoritmi per la correzione della dipendenza energetica della risposta e la discriminazione delle tracce di fondo.Al termine della realizzazione del sistema è stato avviata la sua introduzione nella routine del servizio di dosimetria. Ciò costituisce il delicato ed importante anello di congiunzione fra l'attività di ricerca e l'attività di routine di dosimetria, che comporta il passaggio dalla fase prototipale e/o sperimentale alla fase di routine, caratterizzata da tempi, numeri, tipo di misure ben diversi da quelli studiati durante gli studi e le ricerche. Ciò comporta l'effettuazione di una serie di procedure e verifiche, raramente descritte in letteratura e qui riportate, fondamentali per l'implementazione reale dei risultati degli studi e l'effettivo miglioramento della qualità del servizio fornito.Il presente lavoro illustra, inoltre il confronto delle prestazioni del nuovo sistema con quelle del sistema semi-automatico fino ad ora in uso, sulla base delle misure di routine di un periodo di controllo del servizio di dosimetria.

Preliminary results of an inter-laboratory collaborative work on the application of computerised glow curve analysis to TL personal dosimetry are presented. Very simple analysis methods have proved to be useful for the evaluation of glow curves similar to those encountered in the dosimetric control of radiation workers. A first result obtained in the study has been the possibility of simplifying the TL working procedures by eliminating pre-annealing or pre-heating steps employed in conventional systems to avoid low temperature peaks. The presence of these unwanted peaks can be detected by the computerised evaluation methods, discriminating their contribution to the dosimetric TL data.

The energy dependence of the response function S(E), of CaF2:Tm (TLD-300) thermoluminescent material (3.2 x 3.2 x 0.90 mm3 ribbons) was measured from 6 keV up to 1250 keV (60Co) using 55Fe, 137Cs and 60Co gamma ray sources as well as X ray ISO reference beams. To the best knowledge of the authors the data for energies below 45 keV are reported for the first time. The S(E) function was also calculated in the energy range from 1 keV up to 20 MeV and compared with the experimental data. relative to the total glow curve. The comparison shows good agreement from 1250 keV down to 40 keV. At lower energy the discrepancy increases. This is interpreted in terms of the X ray attenuation within the thickness of TLD-300. Finally, measurements point out the effects of different reading and annealing treatments on the measured function S(E).

The ENEA fast neutron dosemeter is based on a planar P ADC (Poly Allyl Diglicol Carbonate) placed in a polyethylene holder. The employed CR39 (Registered Trademark of PPG Industries Inc.) material, produced by Intercast Europe S.p.A., has been introduced in the routine of the Individual Monitoring Service since 1998. Since then, acceptance tests on average sheet background track density and sheet neutron sensitivity have been made on new batches as a quality control within a Quality Assurance programme of the Individual Monitoring Service (IMS) of ENEA - Institute far Radiation Protection (IRP). Dosemeters have been irradiated with 241Am-Be source at ENEA-IRP and processed through a chemical etching procedure (pre-etching with 40% KOH water solution 6.25 N and 60% ethyl a1cohol at 70°C followed by 12 hours etching in 6.25 N KOH water solution). Herein we present the analysis of acceptance testing data for more than 30 sheets of CR-39 plastic produced in 1998, 1999 and 2000.Moreover, we compare the performance of sheets of CR-39 of standard composition with the one of sheets of CR-39 with the addition of DOP (Dioctylphthalate), in different concentrations, on the basis of average background density, neutron sensitivity and background fluctuation that limits the lower detectable dose.The study enhances the need of acceptance tests to assure the quality of the dosimetric performance of the dosemeters, which is considerably dependent on the quality of the CR-39 plastic.

The medical staff performing interventional cardiology and radiology (IC/IR) procedures stand close to the patient and thus close to the primary radiation beam. Although they wear a lead apron and thyroid collar, their hands, legs and eyes are not protected. Therefore, these parts could receive significantly high doses. Moreover, thedose ranges for the same kind of procedures vary a lot, as many factors affect extremity and eye lens doses. Additionally, there is evidence that eye lens doses can be high in IR/IC, and cases of cataract have been reported in recent years. A lack of an appropriate eye lens dosemeter as well as an appropriate calibration procedure has been identified. Medical staff in IR/IC could benefit from the use of active personal dosemeters (APDs) as optimisation tool. However, a lack of appropriate APDs is identified for typical fields in IR and IC. Very few devices can detect low energy fields, and none of them are really designed for working in pulsed radiation fields. In the field of nuclear medicine (NM) the extremity doses to the technologists are also known to be very high. One can highlight the difficulties in estimating the dose distribution across the hands, and the need for greater knowledge of doses received during the main tasks of a nuclear medicine department, especially using unsealed sources. The ORAMED project, (www.oramed-fp7.eu) was set up to optimize the working procedures in these medical fields with respect to radiation protection. ORAMED wasstructured in 5 work packages: - Extremity and eye lens dosimetry in IR and IC - Development of practical eye lens dosimetry - Optimization of the use of APDs in IR and IC - Extremity dosimetry in NM - Training and dissemination A coordinated measurement program in European hospitals was organised both in IR/IC and NM departments. Moreover, simulations of the most representative workplaces/procedures were performed to determine the main parameters that influence the extremity and eye lens doses. Some dedicated studies on improving the eye lens dosimetry and active personal dosimetry were conducted. Based on the measurement and simulation results, a series of practical guidelines and training packages were developed. The influence of the different radiation protection measures (like shields)in IR/IChave been quantified, and clear monitoring requirements have been formulated for a series of medical procedures. A formalism for the use of the operational quantity for eye lens dose measurements have been worked out (calibration phantom, conversion coefficients, type test procedures, ...). A dedicated eye lens dosemeter has been developed that can be used in routine monitoring. The different existing APDs have been tested in fields that are representative for hospital fields (like pulsed fields), and a series of guidelines for the use of these APDs in hospitals have been made. Also, an improved APD device specifically for IR/IC fields has been developed.The extensive measurement and simulation campaign for extremity doses in NM lead to a systematic evaluation of the different radiation protection measures. These are condensed in a series of practical guidelines to be used. The dose distribution across the hands of the technologists was characterised, and recommendations for routine monitoring have been formulated. The outcome of the ORAMED project will improve the radiation protection standards for medical staff. The systematic measurements and simulations are the new standards that will be used for many years to come. The practical guidelines that have been developed can be used in the hospitals by the medical staff. In particular, the developments on the eye-lens dosimetry and the active personal dosemeters will result in an improvement of the practical measurement capabilities in the field.

BNCT of skin malignant melanoma bas been developed in Japan since 1972. Primary lesions and unobservable satellite metastasis can be selectively treated with this technique. The clinical results related to 18 patients treated in Japan up to January 1996 are analysed in ref. 1. The survival rate after two or more years resulted to be 78%, regardless the level of melanoma progression. 10B-paraboronphenylanine (BPA) was used as the boron carrier to the tumour. The patiens were irradiated at a research reactor facility for 1-2 hours with thermal neutrons and the related maximum fluences at the tumour sites were in the range (1.0-2.0)x1013 cm-2.The design of the accelerator-based neutron source for BNCT of skin melanoma discussed in the present work is described in ref. 3. Neutrons are produced by bombarding a thick beryllium target with 7 MeV deuterons. The target is contained in a heavy water moderator in turn enclosed in a graphite structure. Lead filters are placed on the Faraday cup containing the beryllium target and on the heavy water container to reduce the prompt gamma ray dose. The experimental verification of the accelerator-based source was performed at the CN Van De Graaff accelerator of the Laboratori Nazionali di Legnaro (LNL, Italy). Measurements of thermal fluence uniformity and prompt gamma ray dose at the irradiation position, together with estimates of the neutron fluences inside an Alderson phantom are discussed in this paper.