Biomedical subjects

M Angelone

Publications and source records attributed to M Angelone.

9 recordsLinked to original sources

PubMed2006

Inter-comparison among different TLD-based techniques in a standard multisphere assembly for the characterisation of neutron fields.

In the framework of collaboration among the ENEA Radiation Protection Institute (Bologna), the ENEA Fusion Department (Frascati) and the INFN-LNF-Radiation Protection Group (Frascati), an experimental campaign was organised on the usage of thermoluminescence dosemeters (TLDs) for the dosimetric and spectrometric characterisation of neutron fields. Commercially available TLDs of different material and different sensitivity to photons and thermal neutrons were selected, namely TLD600H and TLD700H from Harshaw, GR206 and GR207 from SSDML (China), MCP-6s from TLD Poland. The detectors were first calibrated in standard fields of photons ((60)Co) and thermal neutrons at the ENEA-IRP Secondary Standard Calibration Laboratory of Bologna, then exposed in fast neutron standard fields of different energy, using a standard multisphere moderating assembly. The paper compares the dosimetric characteristics of the studied TL detectors, underlining the (n-gamma) discrimination capability, and discusses their spectrometric performances addressed to radiation protection applications.

Calibration↗

PubMed2006

Neutron detection and dosimetry using polycrystalline CVD diamond detectors with high collection efficiency.

Polycrystalline chemical vapour deposited (CVD) diamond film is an interesting material for neutron detection and dosimetry. However, the use of CVD diamond detectors is still limited by the low-level signal pulse produced because of the high energy required to produce an electron-hole pair in diamond (13.2 eV) and by the reduced charge collection efficiency owing to several types of traps for electrons and holes in CVD films. A new type of CVD diamond detector with high gain (HG) contacts was produced as part of the collaboration between the ENEA Fusion Division and the Faculty of Engineering of Rome 'Tor Vergata' University. In this paper the performance of the HG CVD diamond detector is presented and possible applications of CVD diamond detectors to neutron dosimetry are also discussed.

Crystallization↗

PubMed2004

Dosimetric response of tooth enamel to 14 Mev neutrons.

The electron paramagnetic resonance (EPR) response of tooth enamel in a monenergetic neutron beam of 14 MeV was studied, with the aim to evaluate the relative neutron to (60)Co sensitivity. Three samples of tooth enamel powder were irradiated in air. A whole tooth and a powdered sample were irradiated in a geometrical PMMA phantom, in order to simulate the real exposure of a tooth inside a human head. The measured dose in enamel was compared to the dose calculated by Monte Carlo simulation. The relative neutron to (60)Co sensitivity using different reference materials (air, water and enamel) was evaluated as well. Large differences in sensitivity values were found depending on the reference material: the obtained relative neutron to (60)Co sensitivity was 0.47+/-0.09 for enamel and 0.15+/-0.03 for water. A comparison with results in fast neutron fields is reported.

Computer Simulation↗

PubMed2004

Development and application of CVD diamond detectors to 14 MeV neutron flux monitoring.

CVD diamond is an interesting material for radiation detection, its atomic number (Z = 6) is close to that of soft tissues (Z = 7.1) and it can also work in harsh environments. Since many years CVD diamond films have been grown at the Faculty of Engineering, Rome 'Tor Vergata' University, and in 1998 a collaboration with ENEA Fusion Division was established to develop fast neutron monitors to be used in fusion tokamak environment. In this paper the first test of a 120 microm thick polycrystalline CVD diamond detector used for monitoring 14.7 MeV neutrons emission produced with the Frascati Neutron Generator (FNG) is reported. The detector operates in air and in pulse mode. The time irradiation profiles recorded with the CVD diamond detector were compared with those recorded by the standard monitors available at FNG (SSD, fission chamber, NE-213). Good stability and capability to operate in neutron flux up to 1.5 x 10(8) n cm(-2) s(-1) was observed. The radiation hardness property was also investigated using a 460 microm thick film and these results are also reported.

Diamond↗

PubMed2004

In phantom Dosimetric response of tooth enamel to neutrons.

Electron Paramagnetic Resonance dosimetry based on tooth enamel has one important application in dose reconstruction of nuclear plant workers, where the contribution of neutrons to individual dose is often important. Evaluation of tooth enamel response to neutrons is thus an important goal. A few experimental data at thermal and fast neutron energies are available. A first evaluation of the tooth enamel relative response to 60Co in monoenergetic neutron flux of 2.8 and of 14 MeV, published elsewhere, has provided results apparently non-consistent with the results obtained at lower and higher energies. A comparison of those results in the 2.8 and 14 MeV beams with those available in the literature for other beams is reported and possible reasons for incongruities are discussed. Dose conversion factors of enamel to the water and air are also calculated and reported.

Algorithms↗

PubMed2002

Platinum levels in natural and urban soils from Rome and Latium (Italy): significance for pollution by automobile catalytic converter.

Platinum concentrations in topsoil samples collected in 1992 (48) and in 2001 (16) from the urban area of Rome have been determined by ICP-MS. Concentrations in 47 soil samples collected in 1992 from natural sites of Latium (an area around Rome) have been determined for a first assessment of natural background levels. The Pt concentrations in Rome urban soils collected in 1992 range from 0.8 to 6.3 ng/g (mean = 3.8 +/- 1.0) overlapping the concentration range of natural soils from Latium (mean = 3.1 +/- 2.1 ng/g). No significant correlation has generally been found between Pt contents in the 'natural' soils and related bedrock or major pedogenetic parameters. These results suggest that there is no evidence of Pt pollution in Rome urban soils at that time, because the massive use of the automobile catalytic converter has only just started. Higher (up to six times more) Pt concentrations, than those measured in the 1992 samples, have been measured, in some cases, in Rome urban soils collected in 2001, suggesting a possible start of Pt accumulation because of the large-scale use in the last decade of automobile catalytic converters. At the same time, a clear decrease of lead levels in Rome urban soils with respect to the levels measured in 1992 has been observed, paralleling the decreasing number of lead gasoline-fuelled cars. Here we present one of the first systematic studies for defining background levels of Pt in Italian natural soils, thus allowing for monitoring, in the future, should any possible Pt pollution caused by the use of automobile catalytic converter, especially in urban soils, occur.

Air Pollutants↗

PubMed2002

Energy dependence of TLD-300 response from 6 keV up to 1250 keV.

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).

Calcium Fluoride↗

PubMed2001

Measurement of the mass attenuation coefficient for elemental materials in the range 6 < or = Z < or = 82 using X-rays from 13 up to 50 kev.

The mass attenuation coefficients for 22 high purity elemental materials (C, Al, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Rh, Pd, Ag, Cd, In, Ta, Pt, Au, Pb) were measured in the X-ray energy range from 13 up to 50 keV using a high purity germanium detector with thin (50 microm) Be window and a variable-energy X-ray source. The measured values are compared with the theoretical ones obtained using the XCOM code and data base, as well as with other experimental data showing a general agreement within +/- 5%. The mass attenuation cross-sections were thus derived and compared with other experimental data available on the 1988 NBS database of X-ray attenuation cross-sections. The agreement is always within +/- 8%, but for a few points the discrepancies are up to +/- 18%. The data analysis has also shown that some measurements performed at 50.65 keV as well as at 36.65 keV are to be considered as new data for most of the measured materials.

Journal Article↗

PubMed1998

Measurement of the neutron sensitivity of TLD-300 irradiated in a tissue equivalent phantom by d(48.5) + Be neutrons.

The neutron sensitivities of the total response (kT) as well as of separate peaks 3 (k3) and 5 (k5) on the glow curve were measured for CaF2:Tm (TLD-300) thermoluminescent dosimeters. The TLD-300 were encapsulated in A-150 TE plastic and located at different depths in the water phantom. The phantom was irradiated with neutrons produced by the d(48.5) + Be reaction at the superconducting cyclotron of the Gershenson Radiation Oncology Center at Harper Hospital. A set of measurements, based on the use of a TE ionization chamber and Geiger-Müller (GM) counter was used to measure the neutron (Dn) and gamma (D gamma) dose at these locations. The neutron sensitivities of the TLDs were thus derived by comparison with the results obtained with the twin detector method. The average neutron sensitivities relative to gamma of the total response and the responses of single peaks 3 or 5 are 0.215 +/- 0.016, 0.126 +/- 0.010, and 0.357 +/- 0.014, respectively. A linear relationship was found between the ratio of the areas under peak 3 to that under peak 5 and the ratio of the gamma dose to the total dose.

Calibration↗