Investigation of silica-based TL media for diagnostic x-ray dosimetry

We focus on the development of Ge-doped silica thermoluminescent dosimeters with sensitivity superior to that of the LiF (Mg,Ti) phosphors popularly used in x-ray diagnostic imaging dosimetry, typically in the form of the product TLD-100. Of interest are Ge-doped silica telecommunication fibres (SMF) and tailor-made doped photonic crystal fibres (PCFc), the latter Ge-doped or also co-doped with boron. The PCFs are formed of capillaries that at high temperatures and under vacuum are made to collapse inwards (PCFc), the internal walls fusing and generating strain-related defects. To-date, the fabricated PCFc-Ge-B, PCFc-Ge and (SMF) have been observed to provide TL yields which weight-for-weight are some 15, 10 and 2 × that of TLD-100. In present study we test the linearity of TL yield for x-ray doses from 0.1- to 10 mGy, use being made of an x-ray tube operated at 80 kVp, a value typically selected in chest radiography. For a dose of 10 mGy, a study of energy dependence has been conducted using x-ray tube potentials of 80 kVp 100 kVp, and 120 kVp, with inherent filtration 0.9 mm Al measured at 75 kVp, and total filtration of 2.8 mm Al at 80 kVp

Effect of Ionizing Radiation on Hyaluronan and Fibrous Pericardium.

With the development in radiotherapy techniques there has been reduction in side effects compared to the treatment outcomes of some several decades ago. In this same regard, success rates for curative treatments are generally increasing, presenting increased demand for improved radiation cosmesis (i. e. reduction in side effects). This is no less true for those treated for lymphoma, taken together with the associated risks of cardiovascular disease. The extracellular matrix (ECM) is a complex medium comprising the non-cellular functional components that surrounds cells. The ECM is composed mainly of fibrous proteins such as collagen and a gel of carbohydrate polymers called glycosaminoglycans (GAG). The ECM provides a range of vital roles including mechanical support, cell signalling and water and solutes transportation, each potentially modified as a result of irradiation. The aim of this study has been to investigate the effect of penetrating photon irradiation on the biophysical and infrastructural properties of extracellular matrix (ECM) macromolecules. Hyaluronan (HA) molecules and collagen fibres were chosen because of their crucial mediating roles in controlling the physiological functions of the ECM. The present work was guided by doses that can be delivered to the synovial joint and pericardium as a result radiotherapy. In respect of biophysical characterisation, numbers of measurements were conducted for HA solutions, this being the main component of the synovial fluid. Different concentrations in the range (0. 01-1% w/v) were studied. These measurements included viscosity, pH, ultraviolet irradiation (UV), Gel Permeation Chromatography (GPC) (for molecular weight characterisation) and Raman microspectrometry. Mechanical testing, with results controlled by the various structural elements, were performed on pericardium, uniaxial testing and atomic force microscopy (AFM) being used

Effect of ionizing radiation on hyaluronan and fibrous pericardium

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

X-ray fluorescence analysis of Pb, Fe and Zn in kohl

Kohl, a facial salve used in ancient times as a symbol of affluence, now enjoys more widespread traditional followings, for cosmetic, religious and supposed medicinal purposes. Popularly used by women and men of all ages, particularly those of North African, Middle Eastern, Southern Asia, Japanese and Chinese origins, it is also known to be used on neonates and children from such populations. With small-scale producers of kohl possessing a growing awareness of the adverse market impact of products that contain (lead) Pb and other toxicity related elements, some claim their products to be Pb-free, offering an apparent change from the more traditional galena-based (lead sulphide) media. Among the published physiological effects of exposure to Pb is that it replaces Ca in bones and teeth, making them weak and fragile, other impacts including nephrotoxicity, also linked with increased Pb blood levels in studies in Oman, Canada, Saudi Arabia, India and Pakistan. Current study involves XRF analysis of Pb, Fe and Zn concentrations in 135 samples of kohl from nine randomly selected suppliers (15 samples of each brand being represented). In pursuit of this, use was made of an in-house assembled facility comprising compact high-performance components, the arrangement offering sufficient sensitivity for the purposes of present study. In most of the samples investigated in the present study observation has been made of concentrations of Pb at elevated levels, quantification of those levels also demonstrating a need to address self-attenuation by the Pb itself. Significant concentration of Fe have also been found in several of the samples. Keywords: X-ray florescence, Pb, Fe and Zn contamination, Koh