A new standard in testing mattresses for use in x-ray imaging : developing, validating and using a novel method to test x-ray mattresses for pressure ulcer development, radiation dosimetry and image quality

Background In hospitals, patients often undergo X-ray imaging while lying on a mattress. Therefore, mattresses must have low X-ray attenuation properties to minimise radiation dose to the patient. Mattresses should create no artifacts within the X-ray image, as this may compromise image quality and diagnosis. Finally, mattresses should be constructed in such a way that interface pressure (IP) is minimized, limiting the chance of pressure ulcer formation. Aim For evaluating X-ray imaging table mattresses, this thesis has three aims (1). to develop and validate an anthropomorphic-phantom-based method of assessing X-ray table mattress IP as an index of mattress performance; (2) to assess X-ray table mattress pressure redistribution properties; and (3) to evaluate mattress radiation attenuation characteristics and their impacts on image quality. Methods and Materials An anthropomorphic phantom, simulating adult head, pelvis, and heels, was 3D-printed from X-ray computed tomography (CT) image data. Dry sand was added to represent 5 human weights and XSensor technology was used to assess pressure distribution. Phantom mattress IP characteristics were compared for the 5 weights against 27 sets of human mattress IP data to achieve phantom validation. Twenty-four X-ray table mattresses, 21 thinner and 3 thicker were assessed. Anthropomorphic phantom and Xsensor mattress interface pressure measurements were conducted for head, pelvis and heels, with and without X-ray table mattresses. Image quality and radiation attenuation were also assessed. Incident air kerma (IAK) was measured, with and without mattress, over a range of exposure factors using a digital dosimeter. Inverse image Quality Factor (IQFinv) was calculated to assess image quality using a commercially available phantom (CDRAD). Results The anthropomorphic phantom proved suitable for use in this thesis - based on correlation coefficient R values, there was a good correlation for the 5 phantom weights between the phantom and human pressure data. (R values: head =0.993, pelvis =0.997, and heels =0.996). There were statistically significant differences (p<0.05) between peak pressure values with and without X-ray table mattress for head, pelvis and heels. Additionally, there were statistically significant differences (p<0.05) between the IP ratio values with and without X-ray table mattresses. The type and age of the mattresses also had an impact on peak pressure values and IP ratios. IAK and image quality measures were impacted by mattress addition. IAK values decreased because of attenuation, with IQFinv having worse image quality. There was a negative correlation between mattress age and IAK, meaning that older mattresses had higher attenuation properties. The clinical impact of this finding, for the potential for radiation increase, was insignificant. No correlation was found between image quality and age. Conclusion A novel method for testing X-ray mattress IP was established and validated in this thesis. This method could be valuable for aiding mattress design and development and subsequent testing when in clinical use. For new mattresses, peak pressure values and IP ratios were greatly reduced, compared with older ones. The impact mattresses had on radiation attenuation and image quality are clinically insignificant

WDM for Multi-user Indoor VLC Systems with SCM

A system that employs wavelength division multiplexing (WDM) in conjunction with subcarrier multiplexing (SCM) tones is proposed to realize high data rate multi-user indoor visible light communication (VLC). The SCM tones, which are unmodulated signals, are used to identify each light unit, to find the optimum light unit for each user and to calculate the level of the co-channel interference (CCI). WDM is utilized to attain a high data rate for each user. In this paper, multicolour (four colours) laser diodes (LDs) are utilized as sources of lighting and data communication. One of the WDM colours is used to convey the SCM tones at the beginning of the connection to set up the connection among receivers and light units (to find the optimum light unit for each user). To evaluate the performance of our VLC system, we propose two types of receivers: an array of non-imaging receivers (NI-R) and an array of non-imaging angle diversity receivers (NI-ADR). In this paper, we consider the effects of diffuse reflections, CCI and mobility on the system performance

Evaluation of X-ray table mattresses for radiation attenuation and impact on image quality

Introduction Mattresses in the radiology department tend to be an overlooked aspect of imaging equipment. This paper evaluates the radiation attenuation characteristics of mattresses and the effect they have on image quality. Method Thirteen mattresses (from new to 20 years of age) were evaluated. Incident air kerma (IAK) was measured in two conditions, with and without mattress over a range of exposure factors using a digital dosimeter. The percentage change was calculated and applied to the set mAs to illustrate the “effective mAs” delivered to an image receptor. Image quality was assessed by calculating the inverse image quality factor (IQFinv) using a commercially available phantom (CDRAD) for the same exposure factors. The correlation of age and attenuation and image quality was calculated. Results Measured IAK and image quality was affected by the addition of a mattress. IAK decreased due to attenuation and IQFinv indicated worse image quality. IAK correlated negatively with mattress age indicating that older mattresses have higher attenuation properties. The clinical impact for radiation increase was insignificant as it resulted in an average of 0.05 change in mAs. There was no correlation between age and image quality. Conclusion The results indicate that while the presence of a mattress does impact on transmitted radiation and the quality of the image, the clinical impact is insignificant. Attenuation correlates with age but with no clinical significance. There is no correlation between age and image quality. Implications for practice Quality control tests for attenuation and impact on image quality are not required in clinical practice. The method could be used by manufacturers to test new materials and mattresses and could provide users with specifications of new products

Effects of body part thickness on low‐contrast detail detection and radiation dose during adult chest radiography

Introduction Differences in patient size often provide challenges for radiographers, particularly when choosing the optimum acquisition parameters to obtain radiographs with acceptable image quality (IQ) for diagnosis. This study aimed to assess the effect of body part thickness on IQ in terms of low‐contrast detail (LCD) detection and radiation dose when undertaking adult chest radiography (CXR). Methods This investigation made use of a contrast detail (CD) phantom. Polymethyl methacrylate (PMMA) was utilised to approximate varied body part thicknesses (9, 11, 15 and 17 cm) simulating underweight, standard, overweight and obese patients, respectively. Different tube potentials were tested against a fixed 180 cm source to image distance (SID) and automatic exposure control (AEC). IQ was analysed using bespoke software thus providing an image quality figure inverse (IQFinv) value which represents LCD detectability. Dose area product (DAP) was utilised to represent the radiation dose. Results IQFinv values decreased statistically (P = 0.0001) with increasing phantom size across all tube potentials studied. The highest IQFinv values were obtained at 80 kVp for all phantom thicknesses (2.29, 2.02, 1.8 and 1.65, respectively). Radiation dose increased statistically (P = 0.0001) again with increasing phantom thicknesses. Conclusion Our findings demonstrate that lower tube potentials provide the highest IQFinv scores for various body part thicknesses. This is not consistent with professional practice because radiographers frequently raise the tube potential with increased part thickness. Higher tube potentials did result in radiation dose reductions. Establishing a balance between dose and IQ, which must be acceptable for diagnosis, can prevent the patient from receiving unnecessary additional radiation dose

Effect of alkali/mixed alkali metal ions on the thermal and spectralcharacteristics of Dy3+:B2O3-PbO-Al2O3-ZnO glasses

Thermal and spectroscopic features of 50 B2O3–10 PbO–10 Al2O3–10 ZnO–(x) Li2O–(y) Na2O–(z) K2O–1.0 Dy2O3 (mol %) (x = 19, y = 0, and z = 0; x = 0, y = 19, and z = 0; x = 0, y = 0, and z = 19; x = 9.5, y = 9.5, and z = 0; x = 9.5, y = 0, and z = 9.5; x = 0, y = 9.5, and z = 9.5) glasses, that were fabricated by utilizing melt-quenching approach, are investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), optical absorption, photoluminescence excitation (PLE), photoluminescence (PL), and PL decay lifetimes. PL spectra for all the Dy3 +-doped samples show emission bands at 453 nm (blue), 482 nm (blue), 573 nm (yellow), 662 nm (red), and 752 nm (red) corresponding to the 4I15/2 → 6H15/2, 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2, and 4F9/2 → 6H9/2 transitions, respectively, upon excitation at 350 nm. Here, Dy3 +: Li–Na glass shows the highest PL intensity for all identified emissions. The yellow-to-blue (Y/B) emission intensity ratio (varied within the range 1.257–1.376), CIE chromaticity coordinates (x,y) (slight variation between (0.3410, 0.3802) and (0.3495, 0.3872), and correlated color temperatures (CCTs) (changed from 4953 K to 5212 K) are calculated following the PL spectra. Dy3 +: 4F9/2 decay curves show non-exponential behavior and are fitted by the Inokuti-Hirayama (I–H) model, where S = 6 shows best fit, indicating dipole-dipole (d-d) interactions for Dy3 + excited (donor) and ground state (acceptor) ions

Gold-nanoparticles microfiber saturable absorber for mode-locked erbium-doped fiber laser

We demonstrate the generation of 743 fs soliton pulses in erbium-doped fiber laser employing gold-nanoparticles saturable absorber. The mode-locking operation is achieved with gold-nanoparticles/polydimethyl-siloxane composite coated on a microfiber with 10\\mu m}. waist diameter, indicating the availability of fabricated saturable absorber for pulsed operation in 1.55\\mu m} spectral range

Effect of gold-nanoparticle size on microfiber saturable absorber for mode-locked erbium-doped fiber lasers

Effect of gold-nanoparticle size on microfiber saturable absorber for mode-locked erbium-doped fiber lasers The optical performance of passively mode-locked erbium-doped fiber laser incorporating gold-nanoparticles (Au-NPs) of different sizes as saturable absorbers (SAs) was compared. A composite of Au-NPs with polydimethylsiloxane was spin coated on the surface of a microfiber waveguide. The fabricated Au-NP-based SA was deployed in a ring cavity erbium-doped fiber laser and its lasing performance was evaluated by comparing SA characteristics as well as pulse qualities among the different Au-NP sizes. The optimum pulse performance was realized when the SA was fabricated with 20 and 40 nm Au-NP size. For the former, time-bandwidth product of 0.34 was demonstrated which was the closest to its bandwidth-limited pulse. As for the latter, the fabricated SA exhibited 4.0% modulation depth and an average pulse duration of 886.7 fs. The research work has demonstrated the functionality of Au-NPs as a saturable absorption material for ultrashort pulses generation. In addition, the influence of nanomaterial size towards the characteristics of saturable absorbers, ergo the quality of laser pulse, was verified. This finding is also valuable in customizing ultrashort pulse output that can effectively suit system performance need

Mg-modified Zn-Co-Fe-La nano ferrites: a study of structural, morphological, vibrational, electro-optical, dielectric and magnetic evolution

The series of Zn0.4Co0.6−xMgxFe1.9La0.1O4 (x = 0.0, 0.15, 0.30, 0.45, 0.6) nanoferrites prepared via co-precipitation technique. Scherrer and Williamson-Hall (W-H) methods were used to find the crystallite size (29.6–39.2 nm and 31.6–36.3 nm, respectively) and lattice constant was calculated (8.406–8.395 Å). Moreover, Fourier transform infrared (FTIR) spectroscopy revealed the existence of absorption bands along with functional groups. The vibrations of O2- ions at the tetrahedral and octahedral sites were shown by the Raman five active modes. DC resistivity reduced in the range of 5.2961 × 108 Ω cm to 9.6453 × 107 Ω cm for x = 0.0 to x = 0.6, respectively. The maximum DC resistivity and activation energy (0.1035 eV) were obtained at the parent sample (Zn0.4Co0.6Fe1.9La0.1O4). The optical bandgaps reduced from 2.61 to 1.47 eV, as the Mg2+ contents increased. With increasing frequency the dielectric loss and the dielectric constant decrease. The magnetic parameters such as saturation magnetization (Ms = 60.82–25.94 emu/g), remnant magnetization (Mr = 47.82–18.64 emu/g), and coercivity (Hc = 1334–511 Oe) demonstrated reducing trends with the increase of Mg2+ doping. The best magnetic behavior of the as-prepared samples suitable in microwave devices was observed for Zn0.4Co0.6Fe1.9La0.1O4 sample

Pressure distribution analysis of x-ray table mattresses

Background There is a risk of developing pressure ulcers from lying on an X-ray table mattress, if the mattress pressure redistribution properties are poor. Aim: To assess the pressure redistribution properties of ‘new’ and ‘in current clinical use’ X-ray table mattresses. Methods and materials: Twenty one X-ray table mattresses, each of 2.5 cm thickness, were evaluated. An anthropomorphic human phantom of adult stature with five different weights (minimum, first quartile, mean, third quartile and maximum) was used to simulate human head, pelvis and heels (pressure ulcer jeopardy areas). Using Xsensor technology, peak pressure was measured and Interface Pressure Ratio was calculated for the three pressure ulcer jeopardy areas ‘with’ and ‘without’ an X-ray table mattress. Results: For all mattresses, statistically significant differences (p<0.05) were found between the peak pressure values with and without using an X-ray table mattress for the three pressure ulcer jeopardy areas; similarly, for all mattresses, statistically significant differences (p<0.05) were found between the Interface Pressure Ratio values with and without using x-ray table mattress. The type and age of the mattress was observed to have an impact on peak pressure values and Interface Pressure Ratios, with older mattresses performing worse. Conclusion: Peak pressure values and Interface Pressure Ratios are reduced significantly when using newer X-ray table mattresses. This could be because newer mattresses use more appropriate materials in their construction and/or older mattresses have lost their pressure redistribution properties. Radiology departments should consider assessing mattresses pressure redistribution properties, perhaps on an annual basis