Study has been made of the thermoluminescence (TL) yield of various glass-based commercial kitchenware (Reko-China, Skoja-France, Godis-China, Glass Tum-Malaysia, Lodrat-France). Interest focuses on their potential for retrospective dosimetry. Use was made of a60Co gamma-ray irradiator, delivering doses in the range 2-10 Gy. Results for the various media show all the glassware brands to yield linearity of response against dose, with a lower limit of detection of ∼0.06 and ∼0.08 Gy for loose and compact powdered samples. Among all of the brands under study, the Lodrat glassware provides the greatest sensitivity, at 6.0 E+02 nC g-1 Gy-1 and 1.5E+03 nC g-1 Gy-1 for compact- and loose-powdered forms respectively. This is sufficiently sensitive to allow its use as a TL material for accident dosimetry (2 Gy being the threshold dose for the onset of a number of deterministic biological effects, including skin erythema and sterility). Energy Dispersive X-ray (EDX) analyses have been conducted, showing the presence of a number of impurities (including C, O, Na, Mg, Al, Si, Ca and Br). Fading of the irradiated glasses show the amount of better than 3% and 5% of the stored energy for both loose and compact powdered samples within 9 days post irradiation. As such, commercial kitchenware glass has the potential to act as relatively good TL material for gamma radiation dosimetry at accident levels. This is the first endeavour reporting the TL properties of low cost commercial kitchenware glasses for gamma-ray doses in the few Gy range, literature existing for doses from 8 Gy to 200 Gy.
As a result of the various evolving needs, thermoluminescence dosimetry is constantly under development, with applications intended in environmental and personal radiation monitoring through to the sensing of radiotherapy and radiation processing doses. In radiotherapy dosimetry challenges include small-field profile evaluation, encompassing the fine beams of radiosurgery, evaluations confronting the steep dose gradients of electronic brachytherapy and the high dose rates of FLASH radiotherapy. Current work concerns the thermoluminescent dosimetric properties of commercial low-cost borosilicate glass in the form of thin (sub-mm to a few mm) plates, use being made of microscope cover-slips irradiated using clinical external-beam radiotherapy facilities as well as through use of 60Co gamma irradiators. In using megavoltage photons and MeV electrons, characterization of the dosimetric response has been made for cover-slips of thicknesses up to 4 mm. Reproducibility to within +/5% has been obtained. In particular, for doses up to 10 Gy, the borosilicate cover-slips have been demonstrated to have considerable potential for use in high spatial resolution radiotherapy dosimetry, down to 0.13 mm in present work, with a coefficient of determination in respect of linearity of >0.99 for the thinner cover-slips. Results are also presented for 0.13- and 1.00-mm thick cover slips irradiated to 60Co gamma-ray doses, initially in the range 5- to 25 Gy, subsequently extended to 5 kGy-25 kGy, again providing linear response.
Among the various types of decorative materials used in Bangladeshi dwellings, the marble/marble stone is one of the most common ones that used largely for enhancing the beauty and/or aristocracy of the dwelling environment. In this study, the most commonly used, six types of marble stones, have been analyzed for retrospective accident dosimetry. With the interest of characterizing several key thermoluminescence properties to examine their potentiality for dosimetry, annealing - irradiation - readout steps have been done chronologically which comprises the analysis of glow curves, relative sensitivity, dose dependence, repeatability and fading. Considering the various TL parameters, marble 'Carrara' imported from Italy present relatively better capability for reconstruction of radiation dose in the dose range of 10-50 Gy. From fading result, it is clear that for reconstruction of absorbed dose up to four weeks of post exposure, the marble 'Carrara' is found to be the most reliable media among the studied marble types. The Zeff values for the various marble samples are found to be in the range of 13.65-19.12, comparing favorably in replace of TLD-200 (Zeff = 16.3) which can be used for low-level environmental radiation dosimetry. Present work constitutes the first study to investigate the potentials of marble stone for reconstruction of absorbed dose in the range of 10-50 Gy dose.
Present research concerns the TL signal stored in chalk of the variety commercially available for writing on blackboards. Samples of this have been subjected to x-ray irradiation, the key dosimetric parameters investigated including dose and energy response, sensitivity, fading and glow curve analysis. Three types of chalk have been investigated, each in five different colours. The samples were annealed at 323 K prior to irradiation. For all three chalk types and all five colours, the dose response has been found linear over the investigated dose range, 0-9 Gy. Regardless of type or colour, photoelectric energy dependency is apparent at the low energy end down to the lowest investigated accelerating potential of 30 kV. Crayola (Yellow) has shown the greatest TL sensitivity, thus selection has been made to limit further analysis to this medium alone, specifically in respect of glow curve and fading study. In addition, elemental compositional and structural change characterizations were made for the same medium, utilizing Energy Dispersive X-Ray (EDX) and Raman spectroscopy, respectively.
Present work concerns polymer pencil-lead graphite (PPLG) and the potential use of these in elucidating irradiation-driven structural alterations. The study provides detailed analysis of radiation-induced structural interaction changes and the associated luminescence that originates from the energy absorption. Thermally stimulated emission from the different occupied defect energy levels reflects the received radiation dose, different for the different diameter PPLGs. The PPLG samples have been exposed to photon irradiation, specifically x-ray doses ranging from 1 to 10 Gy, extended to 30-200 Gy through use of a60Co gamma-ray source. Trapping parameters such as order of kinetics, activation energy and frequency factor are estimated using Chen's peak-shape method for a fixed-dose of 30 Gy. X-ray diffractometry was used to characterize the crystal structure of the PPLG, the aim being to identify the degree of structural order, atomic spacing and lattice constants of the various irradiated PPLG samples. The mean atomic spacing and degree of structural order for the different diameter PPLG are found to be 0.3332 nm and 26.6° respectively. Photoluminescence spectra from PPLG arising from diode laser excitation at 532 nm consist of two adjacent peaks, 602 nm (absorption) and 1074 nm (emission), with mean energy band gap values within the range 1.113-1.133 eV.
Brachytherapy is commonly used in treatment of cervical, prostate, breast and skin cancers, also for oral cancers, typically via the application of sealed radioactive sources that are inserted within or alongside the area to be treated. A particular aim of the various brachytherapy techniques is to accurately transfer to the targeted tumour the largest possible dose, at the same time minimizing dose to the surrounding normal tissue, including organs at risk. The dose fall-off with distance from the sources is steep, the dose gradient representing a prime factor in determining the dose distribution, also representing a challenge to the conduct of measurements around sources. Amorphous borosilicate glass (B2O3) in the form of microscope cover slips is recognized to offer a practicable system for such thermoluminescence dosimetry (TLD), providing for high-spatial resolution (down to
The epithelial-mesenchymal transition (EMT) is a crucial process in cancer progression and metastasis. Study of metabolic changes during the EMT process is important in seeking to understand the biochemical changes associated with cancer progression, not least in scoping for therapeutic strategies aimed at targeting EMT. Due to the potential for high sensitivity and specificity, Raman spectroscopy was used here to study the metabolic changes associated with EMT in human breast cancer tissue. For Raman spectroscopy measurements, tissue from 23 patients were collected, comprising non-lesional, EMT and non-EMT formalin-fixed and paraffin embedded breast cancer samples. Analysis was made in the fingerprint Raman spectra region (600-1800 cm-1) best associated with cancer progression biochemical changes in lipid, protein and nucleic acids. The ANOVA test followed by the Tukey's multiple comparisons test were conducted to see if there existed differences between non-lesional, EMT and non-EMT breast tissue for Raman spectroscopy measurements. Results revealed that significant differences were evident in terms of intensity between the non-lesional and EMT samples, as well as the EMT and non-EMT samples. Multivariate analysis involving independent component analysis, Principal component analysis and non-negative least square were used to analyse the Raman spectra data. The results show significant differences between EMT and non-EMT cancers in lipid, protein, and nucleic acids. This study demonstrated the capability of Raman spectroscopy supported by multivariate analysis in analysing metabolic changes in EMT breast cancer tissue.
Using tailor-made sub-mm dimension doped-silica fibres, thermoluminescent dosimetric studies have been performed for α-emitting sources of 223RaCl2 (the basis of the Bayer Healthcare product Xofigo®). The use of 223RaCl2 in the palliative treatment of bone metastases resulting from late-stage castration-resistant prostate cancer focuses on its favourable uptake in metabolically active bone metastases. Such treatment benefits from the high linear energy transfer (LET) and associated short path length (<100µm) of the α-particles emitted by 223Ra and its decay progeny. In seeking to provide for in vitro dosimetry of the α-particles originating from the 223Ra decay series, investigation has been made of the TL yield of various forms of Ge-doped SiO2 fibres, including photonic crystal fibre (PCF) collapsed, PCF uncollapsed, flat and single-mode fibres. Irradiations of the fibres were performed at the UK National Physical Laboratory (NPL). Notable features are the considerable sensitivity of the dosimeters and an effective atomic number Zeff approaching that of bone, the glass fibres offering the added advantage of being able to be placed directly into liquid. The outcome of present research is expected to inform development of doped fibre dosimeters of versatile utility, including for applications as detailed herein.
Thermoluminescence (TL) materials have a broad variety of uses in various fields, such as clinical research, individual dosimetry, and environmental dosimetry, amongst others. However, the use of individual neutron dosimetry has been developing more aggressively lately. In this regard, present study establishes a relationship between the neutron dosage and the optical property changes of graphite-rich materials caused by high doses of neutron radiation. This has been done with the intention of developing a novel, graphite-based radiation dosimeter. Herein, the TL yield of commercially graphite-rich materials (i.e. graphite sheet, 2B and HB grade pencils) irradiated by neutron radiation with doses ranging from 250 Gy to 1500 Gy has been investigated. The samples were bombarded with thermal neutrons as well as a negligible amount of gamma rays, from the nuclear reactor TRIGA-II installed at the Bangladesh Atomic Energy Commission. The shape of the glow curves was observed to be independent of the given dosage, with the predominant TL dosimetric peak maintained within the region of 163 °C-168 °C for each sample. By studying the glow curves of the irradiated samples, some of the most well theoretical models and techniques were used to compute the kinetic parameters such as the order of kinetics (b), activation energy (E) or trap depth, frequency factor (s) or escape probability, and trap lifetime (τ). All of the samples were found to have a good linear response over the whole dosage range, with 2B grade of polymer pencil lead graphite (PPLGs) demonstrating a higher level of sensitivity than both HB grade and graphite sheet (GS) samples. Additionally, the level of sensitivity shown by each of them is highest at the lowest dosage that was given, and it decreases as the dose increases. Importantly, the phenomenon of dose-dependent structural modifications and internal annealing of defects has been observed by assessing the area of deconvoluted micro-Raman spectra of graphite-rich materials in high-frequency areas. This trend is consistent with the cyclical pattern reported in the intensity ratio of defect and graphite modes in previously investigated carbon-rich media. Such recurrent occurrences suggest the idea of employing Raman microspectroscopy as a radiation damage study tool for carbonaceous materials. The excellent responses of the key TL properties of the 2B grade pencil demonstrate its usefulness as a passive radiation dosimeter. As a consequence, the findings suggest that graphite-rich materials have the potential to be useful as a low-cost passive radiation dosimeter, with applications in radiotherapy and manufacturing.
Present study concerns the radiological character of Malaysian honey. A total of 18 samples (representative of the various most common types) were obtained from various honey bee farms throughout the country. Using a high-purity germanium γ-ray spectroscopic system, the samples were analysed for the naturally occurring radionuclides 226Ra, 228Ra and 40K. The respective range of activities (in Bq/kg) was: 3.49 ± 0.35 to 4.51 ± 0.39, 0.99 ± 0.37 to 1.74 ± 0.39 and 41.37 ± 3.26 to 105.02 ± 6.91. The estimated associated committed effective doses were derived from prevailing data on national consumption of honey, the annual dose being found low compared with the UNSCEAR reference dose limit of 290 μSv y-1. The estimated threshold consumption rate for honey indicates a maximum intake of 339 g/d, which poses an insignificant radiological risk to public health; however, the total dietary exposure may not, the guidance level of 290 μSv y-1 being applicable to dietary intake of all foodstuffs. The study is in support of the cultivation of a healthy lifestyle, acknowledging prevailing radioactivity within the environment.
Obesity is strongly linked with increased risk and poorer prognosis of endometrial cancer (EC). Cancer-associated fibroblasts (CAFs) are activated fibroblasts that form a large component of the tumor microenvironment and undergo metabolic reprogramming to provide critical metabolites for tumor growth. However, it is still unknown how obesity, characterized by a surplus of free fatty acids drives the modifications of CAFs lipid metabolism which may provide the mechanistic link between obesity and EC progression. The present study aims to evaluate the utility of Raman spectroscopy, an emerging nondestructive analytical tool to detect signature changes in lipid metabolites of CAFs from EC patients with varying body mass index. We established primary cultures of fibroblasts from human EC tissues, and CAFs of overweight/obese and nonobese women using antibody-conjugated magnetic beads isolation. These homogeneous fibroblast cultures expressed fibroblast markers, including α-smooth muscle actin and vimentin. Analysis was made in the Raman spectra region best associated with cancer progression biochemical changes in lipids (600-1800 cm-1 and 2800-3200 cm-1). Direct band analysis and ratiometric analysis were conducted to extract information from the Raman spectrum. Present results demonstrated minor shifts in the CH2 symmetric stretch of lipids at 2879 cm-1 and CH3 asymmetric stretching from protein at 2932 cm-1 in the overweight/obese CAFS compared to nonobese CAFs, indicating increased lipid content and a higher degree of lipid saturation. Principal component analysis showed that CAFs from overweight/obese and nonobese EC patients can be clearly distinguished indicating the capability of Raman spectroscopy to detect changes in biochemical components. Our results suggest Raman spectroscopy supported by chemometric analysis is a reliable technique for characterizing metabolic changes in clinical samples, providing an insight into obesity-driven alteration in CAFs, a critical stromal component during EC tumorigenesis.
One of the most well-liked energizing drinks is now tea, which is primarily used in Malaysia. The natural radioactivity in the associated soils where tea plants are cultivated plays a major role in determining the presence of radionuclides in tea leaves. The present study assesses the transfer of radionuclides from soil-to-tea leaves and then estimates the committed effective doses through tea consumption. Tea leaves and the associated soils were obtained from the largest tea plantation area, which is located in the Cameron Highlands, Malaysia. The marketed tea leaves in powdered form were obtained from the supermarkets in Kuala Lumpur. HPGe gamma-ray spectrometry was used to determine the prevailing concentrations of long-lived radioactive materials in tea leaves. Activity concentrations of 226Ra, 232Th, and 40K in tea soils ranged from 49 to 101.7 Bq kg-1, 74.5-124.1 Bq kg-1 and 79.6-423.2 Bq kg-1, respectively, while the respective values in tea leaves are 14.4-23.8 Bq kg-1, 12.9-29.5 Bq kg-1 and 297-387.5 Bq kg-1. Transfer factors of radionuclides showed typical values (<1.0) except for the 40K. The threshold tea consumption rates suggest that one should not consume more than 67 g of tea leaves per day (around 4 g of tea leaves are needed for making 1 cup of tea, so 17 cups per day) to avoid negative health effects. Committed effective doses due to tea consumption are found to be lower (5.18-6.08 μSv y-1) than the United Nations Scientific Committee on the Effects of Atomic Radiation (2000) reference dose guidance limit of 290 μSv y-1 for foodstuffs; however, it should be noted that the guidance limit is recommended for all foodstuffs collectively. Providing data on natural radioactivity in tea leaves grown in Malaysia, this study may help people manage a healthy lifestyle.