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Treatment of food with ionising radiations in order to increase its shelf-life is largely employed in many countries. Because of restrictions issued by different governments on the use of this technique, in addition to the identification of irradiated foodstuffs, it may be important to determine the radiation dose administered to the foodstuffs. An EPR based protocol to reconstruct the administered dose from samples of irradiated meats (rabbit, pork and duck) within an uncertainty of ±25% is reported. © 2010 Elsevier Ltd.

A bipolar transistor, previously investigated as a possible radiation dosimeter and tested under industrial irradiation conditions in high-activity gamma and high-energy, high-power electron beam facilities has been subjected to stability test in order to understand its behaviour and help to improve its performances. Charge carrier lifetime was measured for several sets of transistors which were then irradiated with various doses (3–60 kGy): seven sets with 60 Co gamma rays and eight with a 10 MeV electron beam. After irradiation all the transistors were measured and each set was divided into three groups: one group was left untreated, the second group was heated at 100 °C for 30 minutes and the third group was heated at 150 °C for 30 minutes, for testing the stability of the lifetime. Our data showed that heat treatment quite successfully eliminates post-irradiation changes in the response. Response measurements of the irradiated transistors, heat-treated and untreated, were carried out at room temperature over several weeks after irradiation to establish post-irradiation stability and assess if these transistors could be used for recording dose history. Calibration curves in the range 3–60 kGy for the thermally treated and untreated devices are presented. Dependence of the response of the transistors on the temperature of the measurements in the range 20–50 °C is reported.

We investigate Total Ionizing Dose effects on 4 Mbit Phase Change Memories (PCM) arrays. We demonstrate a high robustness of PCM against ionizing radiation. We irradiated PCM with 8-MeV electrons. Only small variations are measured in the cell distributions after irradiation. The primary cause of these variations is the degradation of the Bit-Line and the Word-Line selector MOSFETs. Finally, radiation does not compromise the functionality of the SET and the RESET operations.

Gamma-irradiated NaCl samples of different origin were studied with the aim to find a reliable, easy-to-use, low-cost standard for the PSL technique, an increasingly used screening method for irradiated food identification. Five different natural salt types (rock and sea salts) purchased in the local markets were studied along with a laboratory-grade NaCl. High sensitivity and reproducibility of the PSL response are good properties of salt, but the pronounced fading of the signal may be a severe limitation of its use as a reference material. The high sensitivity along with the linear dose dependence of the PSL response opens up the interesting possibility of salt as suitable material for retrospective and environmental dosimetry, especially in the case of accidental irradiation or malevolent use of ionizing radiation. Again, the extreme sensitivity of the PSL signal to light and the pronounced fading must be considered limiting factors, and further basic research is required before practical applications of salt be feasible.

Reliability of the photo-stimulated luminescence (PSL) technique, as screening method for irradiated food identification, has been tested with three kinds of herbs and spices (oregano, red pepper and fennel), prepared in two different ways (granular: i.e. seeds and flakes, or powdered), over a long period of storage with different light exposures. The irradiated samples kept in the dark gave always a positive response (the sample is correctly classified as “irradiated”) for the overall examination period. The samples kept under ambient light conditions, in typical commercial glass containers, exhibited a reduction of the PSL signal, more or less pronounced depending on the type of food and packaging. The different PSL response of the irradiated samples is to be related to the quantity and quality of the mineral debris present in the individual food. It was also found that, for the same type of food, the light-induced fading was much stronger for the flaked and seed samples than for the corresponding powder samples, the penetrating capability of light being much more inhibited in powdered than in whole seeds or flaked form samples. The observed light bleaching of the PSL signal in irradiated herbs and spices is of practical relevance since it may lead to false negative classifications.

The electron beam energy is one of the critical parameters for electron processing, since it can affect the dose distribution in the product. We have developed a robust device for monitoring small variations in the electron beam energy that is easy-to-use during an irradiation run. It involves measurement of currents intercepted by two aluminium plates located in the beam. The ratio of these two currents is quite sensitive to the beam energy; sensitivity is optimised by selecting the appropriate thickness of the front plate depending on the beam energy. We had reported on this energy device earlier for the energy range of 7–12 MeV. In the present paper, we have investigated the feasibility of using this energy device at lower energies, from 4 to 6 MeV.

Poly(epsilon-caprolactone) (PCL), an aliphatic polyester, has received much attention because of its possible application as both a biocompatible and a biodegradable material. For biomedical purposes, PCL-based products can be used as drug delivery systems to the human body or tissue engineering scaffold material. In the latter case the three dimensional synthetic scaffolds, implanted at the tissue defect site, provide a frame-work for cells to attach, proliferate and form extra cellular matrix. To enhance bone regeneration process, hydroxyapatite (HA), the main component of the inorganic phase of bone, is generally added to the polymer material. Response of the organism to the implanted composite biomaterial depends on numerous factors, one of the most important is sterilisation. Different procedures can be utilised for sterilisation, among them high energy radiations present many benefits. In fact, because of excellent penetration characteristics of ionising radiations, radiation sterilisation eliminates problems associated with residual and ethylene oxide gas penetration, uniformity of sterilisation, etc. The doses for radiation sterilization for medical devices and health care products are established by procedures defined in standard ISO 11137. For tissue allografts, international tissue bank standard recommended 15 kGy* as a minimum dose for bacteria decontamination and 25 kGy as minimum dose for bacteria sterilization. These doses should be validated using procedures established by ISO 11137. Other international tissue banks recommended dose up to 35 kGy. However, high-energy radiation, in addition killing bacterial life, may also affect material properties and the interaction between the different phase of the material. This study was aimed at evaluating possible irradiation-induced effects on morphological and thermal properties of both inorganic and polymeric components of some PCL-HA composites. To this purpose PCL-HA samples with different PCL/HA ratios were exposed to gamma radiations. The sample irradiation was performed at 50 kGy, dose greater than the recommended sterilization dose range under N2 or air atmosphere. The samples were investigated by vibrational spectroscopy (IR and Raman spectroscopies) coupled to thermal analysis measurements (Differential Scanning Calorimetry and Thermogravimetry) which revealed to be highly sensible to structure variations.

Different studies haave underlined that gamma-irradiation, a common method for sterilization, can induce structural changes on biomaterials (cross-linking, changes in molecular weight and cristallinity) through the formation of aggressive radicals (OH, COO, O2). Poly-epsilon-caprolactone/hydroxyapatite (PCL/HA) samples (synthesized at IMCB-CNR Napoli, Italy) with different composition (100%, 70%, 60%, 50% w/w of PCL) were irradiated in air or under nitrogen at doses of 10, 25 and 50 kGy (dose to water) with gamma-rays from a 60Co Nordion 220 Gammacell at a dose rate of 0.7 kGy/h. Irradiation does were chosen as recommended for sterilization of bone tissue for inactivation of bacteria. The samples were analyzed after each dose with Raman and FT-IR/ATR spectroscopies to study morphology through changes in area, width, intensity and position of bands associated to crystalline and amorphous phases of PCL and HA; spectroscopic data about cristallinity and relative PCL/HA ratios were confirmed by calorimetric methods (TG and DSC). We find out that both PCL and HA were affected by irradiation: amorphous content increased with irradiation, in particular in air. Relevant changes were observed in the IR spectra of HA in carbonate bands. Samples treated under nitrogen showed smaller changes because of the lower concentration of radicals originated from oxygen and water. This study helps to understand how composite biomaterials can react to gamma-sterilization and could be the starting point of further studies on the effect of different types of irradiation and radicals on biomaterials.

Poly(vinyl alcohol) (PVA) films containing methyl viologen (MV2+) that colours blue upon exposure to ionizing radiation were investigated as possible dosimeters for use in radiation processing applications. In order to find the most suitable composition of the PVA-MV2+ film, different concentrations of the dye have been studied. The absorbance values at selected wavelengths, obtained from irradiation of the PVA film containing the most suitable MV2+ concentration, can be satisfactorily related to the absorbed dose over a wide range, from 50 Gy up to 40 kGy. The effects of dose, dose rate, humidity and temperature on the response of the PVA-MV2+ dosimeter film have been studied under laboratory conditions. We conclude that the PVA film containing MV2+ is a promising tool for the absorbed dose measurements in several industrial applications of ionizing radiations.

The electron beam energy monitoring device, previously developed and tested under standard laboratory conditions using electron beams in the energy range 4-12 MeV, has now been tested under industrial irradiation conditions in high-energy, high-power electron beam facilities. The measuring instrument was improved in order to measure high peak current delivered at low pulse repetition rate as well. Tests, with good results, were carried out at two different EB plants: one equipped with a LUE-8 linear electron accelerator of 7 MeV maximum energy used for cross-linking of cables and for medical device sterilization, and the other with a 10 MeV Rhodotron type TT 100 used for in-house sterilization. © 2009 Elsevier Ltd. All rights reserved.

Two different types of window glasses have been investigated as possible routine dosimeters in the range of 1-50 kGy. Glass samples were irradiated with 3.4 MeV and 8.4 MeV electron beams, and the results compared With those obtained by (60)Co gamma irradiation. Due to the strong optical absorption at wavelengths < 3 10 run, even at low closes, Optical measurements were limited to the range 320-700 nm. In both types of glasses, irradiation induced two absorption hands around 410 and 600 run the intensities of which are proportional to close: the 600 nm hand being less sensitive to radiation. These hands have been attributed to non bridging oxygen hole centres existing in two different configurations. Because of the rapid fading of the optical absorbance observed at room temperature immediately after irradiation (> 15% in two days), the samples underwent it post-irradiation thermal treatment (150 degrees C For 20 min) to improve the stability of absorbance. The fading characteristics of the irradiated and thermally treated glasses, kept in the dark at room temperature, were studied for several weeks. A fast decay, whose intensity depends oil the type and energy of the ionizing radiation, wits observed for few clays after irradiation and thermal treatment, followed by a much slower decay. The results Show that this kind of material could be used as routine dosimeters within it certain dose range, its long its proper calibrations are made for each batch of glass and the appropriate precautions are taken when doing calibration and performing routine dosimetr

Results of the characterization studies on a power bipolar transistor investigated as a possible radiation dosimeter under laboratory condition using electron beams of energies from 2.2 to 8.6 MeV and gamma rays from a Co-60 source and tested in industrial irradiation plants having high-activity Co-60 gamma-source and high-energy, high-power electron beam have previously been reported. The present paper describes recent studies performed on this type of bipolar transistor irradiated with 1.9 and 2.2 MeV electron beams in the dose range 5-50 kGy. Dose response, post-irradiation heat treatment and stability, effects of temperature during irradiation in the range from -104 to +22 degrees C, dependence on temperature during reading in the range 20-50 degrees C, and the difference in response of the transistors irradiated from the plastic side and the copper side are reported. DLTS measurements performed on the irradiated devices to identify the recombination centres introduced by radiation and their dependence on dose and energy of the electron beam are also reported.

A poly(ethersulfone) (PES) engineering thermoplastic was used as toughening agent for an epoxy resin. Different percentages of PES in the resin were used, then cured by electron beam irradiation and some samples were thermally post‐cured. The influence of the hydrothermal ageing on all types of samples was studied, measuring the water absorption percentage, the thermal properties, by dynamical mechanical thermal analysis (DMTA), and the toughness, by K|c measurements.

The use of silicon devices as possible radiation monitors and/or dosimeters has been considered since many years because of the effect of ionizing radiation on the physical and electrical properties of these devices. A bipolar transistor investigated under standard laboratory conditions and in industrial irradiation plants having high-activity γ- source and high-energy, high-power electron beam was found to be suitable as routine radiation dosimeter. Tests carried out by irradiating the transistor with electron beams of energy ranging from 2.2 up to 8.6 MeV and 60 Co γ-rays have shown that the response of this transistor is energy dependent. DLTS measurements have been performed on the irradiated devices to identify the recombination centers introduced by the radiation treatment. The influence of radiation energy on the behavior of this device is discussed.

The Sunna dosimeter was introduced for dose determination in the dose range of 50–300 kGy by measuring optically stimulated luminescence. The usefulness of the dosimeter film has already been shown in food irradiation for routine process control. The aim of the present study was to check the performance of the Sunna dosimeter film for process control in radiation sterilization under industrial processing conditions, i.e. at high activity gamma irradiators and at high energy electron beam facilities. To ensure similar irradiation conditions during calibration and routine irradiation “in-plant calibration” was performed by irradiating the Sunna dosimeters together with ethanol–monochlorobenzene transfer standard and alanine reference standard dosimeters. The Sunna dosimeters were then irradiated together with the routine dosimeter of the actual plant during regular production runs and the absorbed doses measured by the different dosimeters agreed within ±2%(1 σ ).

A bipolar transistor, previously investigated as a possible radiation dosimeter, has been tested under industrial irradiation conditions in high-activity gamma and high energy, high-power electron beam facilities. In-plant calibrations have been performed against transfer standard alanine and reference standard ethanol-monochlorobenzene (ECB) dosimeters over an absorbed dose range of 5-45 kGy. Routine irradiations have been done by placing the transistors, side-by-side with the routine dosimeters used in the plants, on product boxes during production runs. The results of the studies have shown that the agreement between the absorbed dose measured by the transistors and other well established routine dosimeters is within +/-3% (1sigma). This indicates that this type of transistors could be used as routine radiation dosimeters in the dose range investigated. (C) 2004 Elsevier Ltd. All rights reserved.

The electron energy is one of the principal parameters that influence the dose distribution within a product treated with a beam of energetic electrons. An easy-to-use and robust device has been developed that can reliably detect day-to-day small variations in the beam energy. It consists of two identical aluminium plates except for their thickness, which are electrically insulated from each other. The thickness of each plate is carefully selected depending on the electron-beam energy. The charge (or current) collected by each plate, while under the beam, is measured by an electrometer. The ratio of the charge (or current) signal from the front plate to the sum of the signals from the front and rear plates is very sensitive to the beam energy. We have used this device with an accelerator with maximum beam energy of 12 MeV. The high sensitivity and robustness make this device quite suitable for process control applications at an e-beam radiation-processing facility.

he effects of a high energy sterilization treatment on poly-e-caprolactone/carbonated hydroxyapatite composites have been investigated. Poly-e-caprolactone is a biodegradable polymer used as long-term bioresorbable scaffold for bone tissue engineering and carbonated hydroxyapatite is a bioactive material able of promoting bone growth. The biomaterials were irradiated by gamma-rays up to doses higher than those recommended for sterilization (up to 50 kGy) under air or nitrogen atmosphere. The effects of the irradiation treatment were evaluated by vibrational spectroscopy (IR and Raman spectroscopies) coupled to thermal analysis measurements (Differential Scanning Calorimetry and Thermogravimetry) and Electron Spin Resonance spectra. Structural changes and damaging effects observed after irradiation were acceptable for the doses required for sterilisation: only a very slight fragmentation of the polymeric chains as well as some defects in the inorganic part of the composites were induced. Moreover, the radiation sensitivity of the biomaterials was found to be almost identical under the two different atmospheres.

Il trattamento con radiazioni ionizzanti, raggi gamma ed elettroni accelerati è un metodo largamente applicato per la sterilizzazione di materiali biocompatibili. La formazione di radicali particolarmente aggressivi (es. OH, COO, O2) in seguito al trattamento con radiazioni ionizzanti può determinare cambiamenti strutturali nel biomateriale in particolare nella cristallinità. Il poli-epsilon-caprolattone/idrossiapatite (PCL/IA) è un biomateriale utilizzato nella ricostituzione dei tessuti ossei che necessita di sterilizzazione prima dell'impianto. Campioni di PCL/IA di differente composizione (100%, 70%, 60%, 50% di PCL) sono stati trattati con radiazioni ionizzanti e successivamente analizzati mediante spettroscopia vibrazionale e calorimetria allo scopo di valutare le possibili alterazioni indotte nella loro composizione e struttura. Gli irraggiamenti sono stati effettuati mediante raggi gamma da 60Co a differenti dosi (0, 10, 25, 50 kGy) (dose in acqua) in aria e in atmosfera inerte. Le dosi sono state scelte sulla base di quelle raccomandate per la sterilizzazione dei tessuti ossei. L'analisi degli spettri Raman e IR ha evidenziato che sia la cristallinità che la composizione dei campioni non subiscono sensibili variazioni in seguito all'irraggiamento fino alla dose di 50 kGy; inoltre non si sono riscontrate differenze negli irraggiamenti effettuati in aria e in azoto. L'unica alterazione del biomateriale, evidenziata mediante calorimetria, è la riduzione della lunghezza delle catene polimeriche, dovuta all'azione dei radicali formatisi nell'irraggiamento.