G. Gualdrini

Extremity exposure in nuclear medicine: preliminary results of a European study.

The Work Package 4 of the ORAMED project, a collaborative project (2008-11) supported by the European Commission within its seventh Framework Programme, is concerned with the optimisation of the extremity dosimetry of medical staff in nuclear medicine. To evaluate the extremity doses and dose distributions across the hands of medical staff working in nuclear medicine departments, an extensive measurement programme has been started in 32 nuclear medicine departments in Europe. This was done using a standard protocol recording all relevant information for radiation exposure, i.e. radiation protection devices and tools. This study shows the preliminary results obtained for this measurement campaign. For diagnostic purposes, the two most-used radionuclides were considered: (99m)Tc and (18)F. For therapeutic treatments, Zevalin(®) and DOTATOC (both labelled with (90)Y) were chosen. Large variations of doses were observed across the hands depending on different parameters. Furthermore, this study highlights the importance of the positioning of the extremity dosemeter for a correct estimate of the maximum skin doses.

Eye lens dosimetry: task 2 within the ORAMED project

The ORAMED (Optimization of RAdiation protection for MEDical staff) project is funded by EU-EURATOM within the 7° Framework Programme. Task 2 of the project is devoted to study the dose to the eye lens. The study was subdivided into various topics, starting from a critical revision of the operational quantity H(p)(3), with the corresponding proposal of a cylindrical phantom simulating as best as possible the head in which the eyes are located, the production of a complete set of air kerma to dose equivalent conversion coefficients for photons from 10 keV to 10 MeV, and finally, the optimisation of the design of a personal dosemeter well suited to respond in terms of H(p)(3). The paper presents some preliminary results.

Principles for the design and calibration of radiation protection dosemeters for operational and protection quantities for eye lens dosimetry

The work package two of the ORAMED project--Collaborative Project (2008-2011) supported by the European Commission within its seventh Framework Programme--is devoted to the study of the eye lens dosimetry. A first approach is to implement the use of H(p)(3) by providing new sets of conversion coefficients and well suited calibration and type test procedures. This approach is presented in other papers in the proceedings of this conference. Taking into account that the eye lens is an organ close to the surface of the body, another approach would be to directly estimate the absorbed dose to the eye lens, D(lens,est) through a special calibration procedure although this quantity is not directly measurable. This paper is a methodological paper that tries to identify the critical aspects of a dosimetry in terms of D(lens).

Experimental determination of CR-39 counting efficiency to α particles to design the holder of a new radon gas dosemeter

Abstract To design a new radon gas dosemeter, the knowledge of the SSNTD α counting efficiency is essential. It depends primarily on the energy and incidence angle into the detector, then on the etching conditions and finally on the track counting procedure. Therefore the elicited efficiency function represents all these factors. The detectors were exposed to α particles at different angles of incidence and energies, by using a 244 Cm source; two alternative NaOH solution etching conditions were tested, 6.25 N 70° C at 6 and 12 h , respectively. The counting was performed with a light microscope, 267×, and with an automatic track analysis procedure. The critical incidence angle dependance on energy, in our standard condition (6 h ) , resulted θ C ( E )=380.0e (−0.286•(E−0.050)) (1−e (−0.186•(E−0.050)) ), and it was used to design our new radon gas holder.

Evaluation of the dose to the patient and medical staff in interventional cardiology employing computational models

Interventional radiology, among guided X-rays procedures, is a methodology characterised by high level of doses, both for the patient and for the medical staff. The aim of the present study is to estimate the dose associated with coronary angiography procedures by means of numerical models (simplified and anthropomorphic) and MCNPX Monte Carlo code. Numerical estimates were supported by measurement performed with a dose area product meter that is commonly employed in such kind of studies. In the present work the main considerations and the preliminary results are presented.

Air kerma to HP(3) conversion coefficients for photons from 10 keV to 10 MeV, calculated in a cylindrical phantom

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.

Variance Reduction with Multiple Responses

Radiation transport problems that involve high attenuation require non-analogue Monte Carlo. Non-analogue techniques [i.e. employing variance reduction (V.R.)] conserve the first moment whilst reducing the second and consequently the variance. However, because V.R. methods employ in one form or another an estimate of the importance (adjoint flux) which is strictly linked to a particular response, they are directed at a single response. V.R. parameters appropriate to one response (in that they significantly reduce the statistical error) may not necessarily be appropriate to another; they may even raise the errors of other responses compared with their analogue values. Thus Monte Carlo may treat problems involving a high attenuation only if a single response (or a set of responses with similar importances) is of interest. Monte Carlo tends to run into trouble when more differential information is required (flux distributions in many energy groups for example).

The Features of the New Radon Gas CR-39 Dosemeter Developed at the ENEA Institute of Radioprotection

Abstract A new radon gas dosemeter (patent pending) has been designed and tested to be used as a routine referenced device to monitor radon exposures in workplaces and dwelling. It has been conceived as a practical tool to be effectively used in the practice of a qualified Service, operating under QA. Monte Carlo simulation has been extensively used to optimize the geometry of the sensible volume of the holder. The diffusion of the sole radon gas is achieved by the special assembly of the holder, which behaves as closed type with air gap. In this paper we introduce, besides a general description of the device, the theoretical results carried out by Monte Carlo simulation, about the sensitivity to the radon gas (4.07 tracks cm −2 / kBq h m −3 ) and the homogeneity of the detector track density. The experimental calibration was executed at NRPB radon chamber.

Fluence to Hp(3) conversion coefficients for neutrons from thermal to 15 MeV.

The recent statement on tissue reactions issued by the International Commission on Radiological Protection in April 2011 recommends a very significant reduction in the equivalent dose annual limit for the eye lens from 150 to 20 mSv y(-1); this has stimulated a lot of interest in eye lens dosimetry in the radiation protection community. Until now no conversion coefficients were available for the operational quantity Hp(3) for neutrons. The scope of the present work was to extend previous evaluations of H*(10) and Hp(10) performed at the PTB in 1995 to provide also Hp(3) data for neutrons. The present work is also intended to complete the studies carried out on photons during the last 4 y within the European Union-funded ORAMED (optimisation of radiation protection for medical staff) project.

A review of voxel model development and radiation protection applications at ENEA

The need of organ absorbed dose evaluation for radiation protection purposes stimulated, since the late 1960s, the development of anthropoid models to be used with radiation transport codes. Very significant improvements were introduced during the years, passing from stylised analytical human models to realistic voxel models based on computed tomography scans or MRI scans, and finally to advanced surface-geometry models. Besides illustrating the main contributions in this field from various international laboratories, this paper illustrates some applications of voxel models to internal (including in vivo monitoring) and external dosimetry for radiation protection.