High-dose Dosimeter Research Articles

Re-Evaluation of Chromium Doped Alumina for Dosimetric Applications

Abstract Many medical examinations involve ionizing radiation. Although the range of available dosimeters is rather wide, their linearity and chemical stability are limited. Recently, there has been a growing interest in new, improved dosimetric materials for emerging applications in medicine and other fields, such as sterilisation of consumer goods and medical instruments, irradiation of seeds, chemical agents and others. One of the classical dosimeters is carbon-doped alumina (Al2O3:C) – a well-established and widely used material for personal and industrial dosimeter with a range of great properties, such as high sensitivity, wide linearity range and relative ease of production and handling. However, the demand for reliable dosimeters in a high-dose range is still only partially fulfilled, and alumina doped with chromium ions (Al2O3:Cr) can be a promising candidate. In this study, we explored alumina doped with chromium porous microparticles synthesized with a sol-gel method as a possible high dose dosimeter and evaluated its thermostimulated luminescence signal, dose response with two irradiation sources and measured long-time fading. It was found that although the TSL signal was quite complex (consisting of two main peaks above room temperature) and the long-term fading was significant (around 50 % in the span of 30 days), with sufficient optimisation the material could be used as a high-dose dosimeter for X-ray and beta irradiation. Wide high dose linearity range, physical and chemical characteristics, as well as low production costs and ease of synthesis make chromium (III) doped alumina a compelling candidate for applicability in various medical and industry fields.

Thermoluminescence properties of high-dose gamma-irradiated diamond films

Thermoluminescence (TL) properties of gamma-irradiated chemical vapor deposition (CVD) diamond films at high doses are presented. Samples of undoped and nitrogen-doped CVD diamonds were exposed to 60Co gamma sources and TL intensity as a function of the dose was analyzed. To evaluate the feasibility of using these materials as TL high-dose dosimeters, reproducibility of the TL signal, and the TL response as a function of absorbed dose from 100 Gy up to 10 kGy were studied. Furthermore, the fading of the TL glow curve was analyzed. Finally, to estimate the kinetics parameter values associated with the trap distribution in the CVD diamond, a computerized deconvolution was carried out by using the general order kinetics (GOK) model.

Dosimetric evaluation of methyl red radiochromic film for radiation processing

PurposeThe purpose of this paper is to present a radiochromic film dosimeter containing polyvinyl alcohol (PVA) matrix and various concentrations of methyl red (MR) dye for high dose measurements.Design/methodology/approachThe MR-PVA films were exposed to irradiation up to 60 kGy using 60Co source of gamma ray. The ultraviolet and visible regions (UV/VIS) spectrophotometry were used to examine the optical density of pre-and post-irradiated dosimeters at 424 nm.FindingsThe dose sensitivity of MR-PVA films increases significantly with increasing MR dye concentrations in the dose range of 5 to 60 kGy. The impact of relative humidity, irradiation temperature, dose rate and the stability of the films has been analyzed. The overall uncertainty of the MR-PVA film dosimeter is 6.12% (Double Standard-deviation, 95% confidence level).Practical implicationsIt was found that the MR-PVA films may be used as high dose dosimeter with an acceptable overall uncertainty in routine industrial radiation processing.Originality/valueThe color bleaching of irradiated MR-PVA films in terms of specific absorbance curves increases significantly with increasing absorbed dose up to 60 kGy.

High-dose dosimetry with Ag-doped phosphate glass: Applicability test with different techniques

Ag-doped phosphate glass from Chiyoda Technol Corp. was tested as a potential high-dose dosimeter. Several tens of glass samples were irradiated to different doses in the range 0–300 kGy and measured using radiophotoluminescence (RPL), optical absorption (OA), thermoluminescence (TL) and electron paramagnetic resonance (EPR) techniques. While RPL and TL signals from such glass saturated at the doses of about 1 kGy, OA and EPR (associated with Ag2+ centers) responses demonstrated a monotonic increase with dose up to the maximum tested dose 300 kGy. Fading of the Ag2+-related EPR signal was about 7% at 4 months and about 10% at 10 months after irradiation; no change was observed for OA measured one month after irradiation. It is concluded that with proper calibration, Ag-doped glass may be used for dose assessment in high-dose applications.

Development of optical fibers for food irradiation dosimeter

Different technologies and methods for enhancing food quality have been developed and applied in the last few decades. One of the latest technologies is by using ionizing radiation. Food irradiation is the technology that improves the safety and extends the shelf life of food by reducing or eliminating harmful microorganisms and insects. In order to provide for food safety, proper control or radiation detector of irradiated food seems very critical to facilitate international trade of irradiated foods and to enhance consumer confidence. In present studies, germanium-doped (Ge-doped) optical fibers of various form and dimensions were used as radiation detector. The fibers were irradiated using electron beam (EPS 3000), with doses from 1 kGy up to 10 kGy, exceeding the dose range of all commercial high dose dosimeters used in food irradiation industry. A study has been made of linearity, reproducibility, and fading. The fibers show a linear dose response over the studied range doses with mean of reproducibility less than 5 % variation between 1st exposure and 2nd exposure. TL fading of Ge-doped flat fibers has been found to be < 8.7%.

Efficient monitoring of dosimetric behaviour for copper nanoparticles through studying its optical properties

Abstract A novel high-dose dosimeter based on γ radiation reduction of copper ions and formation of copper metal inside polymer matrix were investigated. γ radiation induced synthesis of copper nanoparticles (CuNPs) in poly vinyl alcohol films were studied by UV-Visible Spectrophotometer, X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The optical absorption spectra showed that the Cu/PVA nanocomposite films have surface plasmon resonance (SPR) of copper nanoparticles which depending on irradiation doses. Upon γ irradiation these films turns its color from faint blue to deep reddish brown depending on metal ion concentration. The XRD pattern and FTIR spectrum confirm the formation of the CuNPs. The response of Cu/PVA nanocomposite dosimeters depends on both the irradiation doses and concentration of copper precursor. The dose range for these films was from 50 to 650 kGy, revealing its important applications for high dose dosimetry. Cu/PVA nanocomposites films exhibit good post-irradiation stability in dark and light.

Investigation of the electron paramagnetic resonance signal response in gamma-irradiated poly(lactic acid) for high-dose dosimetry

This paper is concerned with the investigation of the Electron Paramagnetic Resonance (EPR) signal response to Co60 gamma-ray radiation on poly(L-lactic acid) (PLA). The aim of this study is to assess the usefulness of PLA as a high-dose dosimeter. The EPR-signal response of PLA has been investigated to determine some of its dosimetric characteristics such as: signal intensity versus gamma dose received, zero-dose response, signal fading, signal repeatability, batch homogeneity, detection threshold, and stability under simulated sunlight exposure. It is concluded that PLA might be used as a high-dose dosimeter.

EFFECT OF GAMMA RADIATION ON A MIXED DYE FILM AND ITS POSSIBLE USE AS A RADIATION DOSIMETER

Dyed poly vinyl alcohol (PVA) films prepared by a simple technique of casting aqueous PVA solution incorporating a mixture of two dyes namely chlorophenol red (CPR) and Quinaldine Red (QR) on a horizontal glass plate are useful as high dose dosimeter in the dose range 2-30 kGy range. The colour of these films change from deep red to yellow when exposed to gamma radiation. Chloral hydrate was added with different concentrations. The response of the prepared films can be modified either by change of chloral hydrate concentration or ratio of the two dyes. As a result, these films can be used as a dosimeter in two dose ranges. The dosimetric parameters, e.g.; dose response, effect of relative humidity on response as well as pre- and post-irradiation stability of these films were investigated.

Novel radiochromic dosimeters based on Calcein dye for high dose applications

New compositions of radio-chromic solutions and polyvinyl alcohol (PVA) films containing different concentrations of Calcein dye have been introduced as high dose dosimeter. The dosimeters were irradiated with gamma rays from C60o source at doses from 5 to 30kGy for film and from 0.25 to 1kGy for solution. UV/vis spectrophotometry was used to investigate the absorbance (optical density) of unirradiated and irradiated films and solutions in terms of absorbance at 493nm for film and 496nm for solution. The effects of scan temperature, relative humidity and stability of the response of films and solutions after irradiation were investigated. The results show that these films could be used as dosimeter in industrial radiation processing. The useful dose range of developed Calcein-PVA film and solution dosimeters is in the range of 5–20kGy and 0.25–1kGy respectively

TL and EPR correlations in a quartz-like silicate mineral

A sample of silicate mineral considered as being jadeite but revealed to be more quartz-like, therefore named JQ2 has been studied concerning its TL and EPR properties. This study revealed a full correlation between the 210 °C TL peak and the g=2.0025 EPR signal. In both cases, the centers disappear at the same temperature and are restored after gamma irradiation. The TL peak at 210 °C may be related to the E'1 centers formed on irradiation. JQ2 responds to very high γ-dose and can be used as a high-dose dosimeter using TL and/or EPR techniques.

Synthesis and Thermoluminescence of Scandium-Titanium Based Oxide Mixture

ABSTRACTRecently, the research team synthesized some scandium- and titanium-based oxide compounds, in order to analyze their thermoluminescent (TL) response [1-2]. The oxides mixture Sc2TiO5:Eu2Ti2O7:Sc2O3 was synthesized in equilibrium phase by solid state reaction at 1100 °C / 48 h. The structural characterization was performed by XRD and SEM. The TL properties of this oxide mixture were examined after exposing it to gamma radiation from a 60Co source. The glow curve showed two main glow peaks at 151 °C and 260 °C, yet the curve shape looks quite complex, revealing that it is composed by overlapped individual TL peaks, which was confirmed with the Tstop preheat method performed [3]. The linear dose-response between 150 to 600 Gy was obtained, followed by a slow saturation stage. The intensity of the glow curves increases as the radiation dose increases, and their maxima remain at the same temperature values, which indicates that the TL phenomenon follows first-order kinetics [4]. After ten irradiation-TL readout cycles at 500 Gy, good stability (SD 2.02 %) between TL integrated response and the exposure dose was found. It is concluded that Sc2TiO5:Eu2Ti2O7:Sc2O3 is a promising material to use as high-dose dosimeter.

A new developed radiochromic film for high-dose dosimetry applications

A colorless polyvinyl butyral film (PVB) based on a radiochromic leuco brilliant blue cyanide dye (LBB), was investigated as a high-dose dosimeter for gamma radiation processing applications in the dose range of 3–165 kGy. The useful applications for such dose range are food irradiation treatment, medical devices sterilization, and polymer modification. Upon γ-ray exposure, the prepared film undergoes visual color change to deep blue color characterized with an absorption band peaking at 638 nm. The variation in response of irradiated film stored in the dark and under laboratory light illumination was less than 5% during the first week of storage. The effect of temperature and relative humidity on the performance of film during irradiation and the overall uncertainty associated with absorbed dose monitoring were investigated in the present study.

Calcium carbonate as a possible dosimeter for high irradiation doses

The aim of this work is to analyze the interactions of 5MeV electron beam radiation and a 290MeV/u Carbon beam with calcium carbonate (powder) at 298K and at different irradiation doses, for the potential use of calcium carbonate as a high-dose dosimeter. The irradiation doses with the electron beam were from 0.015 to 9MGy, and with Carbon beam from 1.5kGy to 8kGy.High-energy radiation induces the formation of free radicals in solid calcium carbonate that can be detected and measured by electron paramagnetic resonance (EPR).An increase of the EPR response for some of the free radicals produced in the sample was observed as a function of the irradiation dose. These measurements are reproducible; the preparation of the sample is simple and inexpensive; and the signal is stable for several months. The response curves show that the dosimeter tends to saturate at 10MGy. Based on these properties, we propose this chemical compound as a high-dose dosimeter, mainly for electron irradiation.

High- and very-high-dose dosimetry using silicate minerals

In the present study, certain natural silicate minerals such as aquamarine (AB), morganite (PB), goshenite (WB), white jadeite (JW), green jadeite (JG), pink tourmaline (PT) and two varieties of jadeite-like quartz, denoted here by JQ1 and JQ2, were investigated using the thermoluminescence technique to evaluate their potential for use as very-high- and high-dose dosimeters. These minerals respond to high doses of γ-rays of up to 1000 kGy and often to very high doses of up to 3000 kGy. The TL response of these minerals may be considered to be satisfactory for applications in high-dose dosimetry. Investigations of electron paramagnetic resonance and optically stimulated luminescence dosimetry are in progress.

Characterization of silences acid dosimeter for gamma-radiation dosimetry

Silences acid has been investigated as a dosimeter for high doses of Gamma radiation through measuring the induced changes in optical absorbance from (315-900) nm at room temperature. It was found that the absorbance increased with increasing absorbed Gamma-dose. Also, the dose rate and post irradiation fading of optical absorption spectra has been studied. The results of this preliminary study show that Silences acid may be applied as a simple optical absorbance detector for dose measurement in the dose range (5 - 28 ) kGy.

Post-Irradiation Study of the Alanine Dosimeter.

Post-irradiation stability of high-dose dosimeters has traditionally been an important measurement influence quantity. Though the exceptional stability of the alanine dosimeter response with time has rendered this factor a non-issue for routine work, the archival quality of the alanine dosimeter has not been characterized. Here the alanine pellet dosimeter response is measured up to seven years post-irradiation for a range of absorbed doses. This long-term study is accompanied by an examination of the environmental influence quantities (e.g., ambient light) on the relatively short-term (3–4 month) stability of both pellet and film commercial dosimeters. Both dosimeter types demonstrated exceptional stability in the short term and proved to be relatively insensitive to common influence quantities. The long-term data revealed a complex dose-dependent response trend.

A radiochromic film based on leucomalachite green for high-dose dosimetry applications

A colorless polyvinyl butyral film (PVB) based on radiation-sensitive dye of leucomalachite green (LMG) was investigated as a high-dose dosimeter for gamma radiation processing applications in the dose range of 3–150 kGy. The useful applications for such dose range are food irradiation treatment, medical devices sterilization and polymer modification. Gamma irradiation of the film induces a significant intensity of green color, which can be characterized by a main absorption band at 627 nm and a small band at 425 nm. The variation in response of irradiated film stored in the dark and under laboratory light illumination was less than 3% during the first 6 days of storage. The response of film during irradiation was slightly influenced by relative humidity in the range of 12–76%; however, it was significantly affected by temperature in the range of 5–40 °C. The radiation chemical yield was reported to be 6.76 × 10−6 mol/J at the absorbed dose of 30 kGy for the film containing 6.5% of LMG dye. The overall uncertainty associated with routine dose monitoring would be less than 6% at a 95% confidence level if the dosimeter was being corrected for irradiation conditions and being calibrated with reference standard dosimeter in the production facility.

Study the Effect of Gamma Radiation on the Optical Energy Gap of Poly(Vinyl Alcohol) Based Ferrotitanium Alloy Film: Its Possible Use in Radiation Dosimetry

Ferrotitanium alloy polymer films, prepared by a simple technique of casting aqueous solutions of poly(vinyl alcohol) PVA containing ferrotitanium alloy on a horizontal glass plate, are useful as routine high-dose dosimeters. These flexible plastic film dosimeters have pale yellow color, are bleached when exposed to gamma rays. The chemical composition of alloy was determined by EDX, and structure of alloy was determined by XRD. The response of these dosimeters depends on the concentration of alloy. The energy band gap Eg was calculated and the effect of gamma radiation on its value was determined. The optical absorption spectra showed that the absorption mechanism is an indirect allowed transition which found that energy band gap Eg decreases after irradiation. The response of these films has negligible humidity effects on the range of relative humidity from 0 to 100%. And also, it exhibits good preand post-irradiation stability in dark and light.

OSL technique for studies of jasper samples

Jasper samples (green, red, brown, ocean and striped) were studied in relation to their optically stimulated luminescence (OSL) dosimetric properties, in this work. Since 2000, the radiation metrology group of IPEN has studied different stones as new materials for application in high-dose dosimetry. The jasper samples were exposed to different radiation doses, using the Gamma-cell 220 system (60Co) of IPEN. Calibration curves were obtained for the jasper samples between 50Gy and 300kGy. The reproducibility of the OSL response and the lower detection doses were determined. All five types of jasper samples showed their usefulness as irradiation indicators and as high-dose dosimeters, using the OSL technique.

Dosimeter Film Based on Ethyl Violet-Bromophenol Blue Dyed Poly(Vinyl Alcohol)

Dyed poly(vinyl alcohol) (PVA) films, prepared by a simple technique of casting aqueous solutions of PVA containing a mixture of Ethyl violet and bromophenol blue (EV-BPB) on a horizontal glass plate, are useful as routine high-dose dosimeter in the 1 - 30 kGy range. The color of films changes from violet to yellow when exposed to gamma radiation. The response of this dosimeter depends up on the concentration of chloral hydrate (CH) in the polymer material. The radiation chemical yield (G-value) of PVA dyed film was calculated and found to increase by increasing concentration of chloral hydrate. Post-irradiation storage on the response of the films are discussed. The overall combined uncertainty (at 2σ) associated with measurement of response (ΔA mm-1) at 600 nm for dose range 1 - 15 kGy is 5.6%.