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Computed tomography urography (CTU) comprehensively evaluates the urinary tract. However, the procedure is associated with a high radiation dose due to multiple scan series and therefore requires optimisation. The study performed CTU protocol optimisation based on a reduction in tube voltage (kV) using quality assurance (QA) phantom and clinical images and evaluated image quality and radiation dose. The study was prospectively conducted on patients referred for CTU. The patients were grouped into A and B and were scanned with the standard protocol, a protocol used for the routine CTU at the CT centre before optimisation, and optimised protocol, a protocol with reduced kV respectively. The protocols were first tried on a quality assurance (QA) phantom before being applied to patients, and image quality was assessed based on signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). In addition, the clinical images were assessed based on the visibility of the anatomical criteria for CT images by five observers with >5 years of experience. The data were analysed using both visual grading characteristic (VGC) curves and statistical package for social sciences (SPSS) version 22.0. The dose was significantly lower in the optimised protocol with a 10 % reduction in both volume computed tomography dose index and (CTDIvol) and dose length product (DLP) for the phantom images, and a 26 % reduction in CTDIvol and 28 % in DLP for the clinical images. However, there was no significant difference in image quality noted between the standard and optimised protocols based on the quantitative and qualitative image quality evaluation using both the QA phantom and clinical images. The findings revealed a significant dose reduction in the optimised protocol. Further, image quality in standard and optimised protocols did not differ significantly based on quantitative and qualitative methods. kV optimisation in contrast-enhanced procedures provides dose reduction and should be encouraged in the medical imaging departments. [ABSTRACT FROM AUTHOR]

To investigate the influence of material and printing orientation on wear resistance and flexural properties of one low force SLA- and two DLP-printed splint materials and to compare these 3D-printed splints to a subtractively manufactured splint material. Two DLP-printed (V-Print splint, LuxaPrint Ortho Plus) and one low force SLA-printed (Dental LT Clear) material, where specimens were printed in three printing orientations (0°, 45°, 90°), were investigated. In addition, one milled splint material (Zirlux Splint Transparent) was examined. A total of 160 specimens were produced for both test series. The two-body wear test was performed in a chewing simulator (80′000 cycles at 50 N with 5–55 °C thermocycling). Steatite balls were used as antagonists. The wear pattern was analyzed with a 3D digital microscope in terms of maximum vertical intrusion depth (mm) and total volume loss (mm³). The flexural properties were investigated by three-point bending in accordance with ISO 20795-1: 2013 (denture base polymers). The flexural strength (MPa) and the flexural modulus (MPa) were measured. Two-way ANOVA was performed to investigate the effects of the two independent variables material and printing orientation for the three 3D-printed materials. The comparison of the printing orientations within one material was carried out with one-way ANOVA with post-hoc Tukey tests. Two-way ANOVA revealed that wear and flexural properties are highly dependent on the 3D-printed material (p < 0.001). Across groups, a significant effect was observed for wear depth (p = 0.031) and wear volume (p = 0.044) with regard to printing orientation but this was not found for flexural strength (p = 0.080) and flexural modulus (p = 0.136). One-way ANOVA showed that both DLP-printed groups showed no significant differences within the printing orientations in terms of wear and flexural properties. Dental LT Clear showed that 90° oriented specimens had higher flexural strength than 0° oriented ones (p < 0.001) and 45° oriented specimens also showed higher values than 0° ones (p = 0.038). No significant differences were observed within the printing orientations for flexural modulus and wear behaviour within this group. T-tests showed that the milled splints exhibited statistically higher wear resistance and flexural properties compared to all three 3D-printed splint materials (p < 0.001) and that highly significant differences were found between the 3D-printed splint materials for both test series. Within the limitations of this in vitro study, it can be stated that wear behaviour and flexural properties are highly dependent on the 3D-printed material itself. Currently, milled splints exhibit higher wear resistance and flexural properties compared to 3D-printed splint materials. The printing orientation has a minor influence on the properties investigated. Nevertheless, two-way ANOVA also showed a significant influence of printing orientation in the wear test across groups and one-way ANOVA detected significant effects for SLA material in terms of flexural strength, with printing in 90° showing the highest flexural strength. Therefore, anisotropy was found in SLA material, but it can be limited with the employed printing parameters. Both DLP-printed materials showed no significant difference within the printing orientation. [ABSTRACT FROM AUTHOR]

This article discusses the development of mathematical support and software for detecting anomalous behavior of users based on biometric characteristics of their behavior analysis. One of the challenges in intelligent UBA systems is acquisition of useful information from a large volumes of unstructured, unmatched data. Methods and algorithms of intelligent data processing and machine learning used in UBA/DSS systems help to work on a task of solving problems of data analysis of different directivities. It is proposed an application of machine learning methods in implementation of mobile UBA system. There was formed the list of the most significant factors submitted to the input of the analyzing methods during the study. Two approaches of detecting abnormal user behavior have been proposed. The application of machine learning techniques in intelligent UBA systems will make it possible to predict information risks and insider excfiltration of these organizations in advance. [ABSTRACT FROM AUTHOR]

While motion pictures have traditionally been captured and presented at a frame rate of 24 frames!s, recent advancements have enabled the capture and presentation at higher frame rates o f48, 60, and even 120framesls. Capture and presentation at higher frame rates provide improvements in clarity and motion rendition but come at the cost of increased storage space, processing, and workload for the entire motion picture. Motion picture creators want the capability to reduce the motion judder and blur associated with capturing moving images while still maintaining the cinematic feel of their creations. By introducing a method where the projector can vary the frame rate during playback, the scenes that most benefit from higher frame rates can be captured and presented at that rate, while the scenes that do not benefit from higher frame rates can be captured and presented at lower frame rates. The engineers working with DLP Cinema at Texas Instruments have come up with a method to allow changes to the displayed frame rate to be communicated effectively through the entire playback chain during a presentation with no visible artifacts on screen before, during, or after the transition. This variable frame rate capability enabled by the latest DLP Cinema systems is further described in this paper. [ABSTRACT FROM AUTHOR]

Background Inspite of potential detriment from computed tomography (CT) procedures, there is increasing installation and use of the medical imaging modality in Nigeria. Computed tomography dose monitoring and reporting have however, not received commensurate attention. Objective To carry out a census of CT scanners in Nigeria and, to assess a representative sample for dose. Methodology A physical count of the scanners was done using radiographers spread across the country. Twenty of those scanners were then assessed for head dose using volume computed tomography dose index (CTDI vol ), and dose-length product (DLP) extracted retrospectively and manually from the operating console. The mean, as well as the 75th percentile, were then calculated for all subjects with the aid of statistical packages for the social sciences (SPSS), version 20.0. Results A total of 183 CT scanners were installed in Nigeria as at March 2018. A huge number of these (57.4%, n = 105) belonged to private investors while the federal and state governments jointly owned 78 scanners (42.6%). The Christian-dominated South had far more scanners installed (n = 116) than the Muslim-dominated North and FCT (n = 67). Three states in northern Nigeria had no single scanner installed. A sizeable number (83%, n = 151) of the scanners were functional as at March 2018. The CT dose was assessed using scanners from General Electric (GE), Toshiba, Philips, Siemens and Neusoft. CereTom was the only model left out due to low distribution and inaccessibility. The slice capacity ranged from 4 to 128. Tube potential was uniform (120 kVp) in the centres while tube current was within a narrow range (200–250 mA). The dose for head investigation amongst the adult population had a mean/75th percentile of 57/63 mGy (CTDI vol ) and 1336/1431 mGy·cm (DLP), respectively. This is fairly comparable to a similar work from Kenya but higher than the recommendations of the European Commission. Conclusion Computed tomography scanners distinctly located in Nigeria were 183. The first installation in the country was in 1987, suggestive of an annual average of 6 installations. Dose from different facilities showed wide variations. The establishment of national diagnostic reference levels (nDRLs) to reduce arbitrariness in dose administration is imperative. While this is awaited, radiographers have a moral and ethical obligation to pay more attention to optimization of patient protection. [ABSTRACT FROM AUTHOR]

Purpose The aim of this study was to evaluate the dimensional accuracy, surface topography of a custom designed, 3D-printed zirconia dental implant and the mechanical properties of printed zirconia discs. Materials and methods A custom designed implant was 3D-printed in zirconia using digital light processing technique (DLP). The dimensional accuracy was assessed using the digital-subtraction technique. The mechanical properties were evaluated using biaxial flexure strength test. Three different build angles were adopted to print the specimens for the mechanical test; 0°( V ertical), 45° ( O blique) and 90°(Horizontal) angles. The surface topography, crystallographic phase structure and surface roughness were evaluated using scanning electron microscopy analysis (SEM), X-ray diffractometer and confocal microscopy respectively. Results The printed implant was dimensionally accurate with a root mean square (RMSE) value of 0.1 mm. The Weibull analysis revealed a statistically significant higher characteristic strength (1006.6 MPa) of 0° printed specimens compared to the other two groups and no significant difference between 45° (892.2 MPa) and 90° (866.7 MPa) build angles. SEM analysis revealed cracks, micro-porosities and interconnected pores ranging in size from 196 nm to 3.3 µm. The mean Ra (arithmetic mean roughness) value of 1.59 µm (±0.41) and Rq (root mean squared roughness) value of 1.94 µm (±0.47) was found. A crystallographic phase of primarily tetragonal zirconia typical of sintered Yttria tetragonal stabilized zirconia (Y-TZP) was detected. Conclusions DLP prove to be efficient for printing customized zirconia dental implants with sufficient dimensional accuracy. The mechanical properties showed flexure strength close to those of conventionally produced ceramics. Optimization of the 3D-printing process parameters is still needed to improve the microstructure of the printed objects. [ABSTRACT FROM AUTHOR]

In emergency departments computed tomography (CT) has became the most important diagnostic tool because it is a very fast and accurate method, but the main drawback of the increased number of the CT examination is the high radiation dose and the potentially increased risk of developing cancer. That why, lowering the radiation dose at a level as reasonable achievable is the most important strategy in modern medical practice. This article has two parts: first part is a review of the physics of radiation dose in CT and the methods that currently can be used to reduce it; the second part is an inter-observer agreement study that tries to validate the feasibility of using different dose reduction methods without compromising the image quality. [ABSTRACT FROM AUTHOR]

For decades, titanium has been the preferred material for dental implant fabrication. However, metallic ions and particles can cause hypersensitivity and aseptic loosening. The growing demand for metal-free dental restorations has also promoted the development of ceramic-based dental implants, such as silicon nitride. In this study, silicon nitride (Si 3 N 4) dental implants were fabricated for biological engineering by photosensitive resin based digital light processing (DLP) technology, comparable to conventionally produced Si 3 N 4 ceramics. The flexural strength was (770 ± 35) MPa by the three-point bending method, and the fracture toughness was (13.3 ± 1.1) MPa · m1/2 by the unilateral pre-cracked beam method. The elastic modulus measured by the bending method was (236 ± 10) GPa. To confirm whether the prepared Si 3 N 4 ceramics possessed good biocompatibility, in vitro biological experiments were performed with the fibroblast cell line L-929, and preferable cell proliferation and apoptosis were observed at the initial stages. Hemolysis test, oral mucous membrane irritation test, and acute systemic toxicity test (oral route) further confirmed that the Si 3 N 4 ceramics did not exhibit hemolysis reaction, oral mucosal stimulation, or systemic toxicity. The findings indicate that Si 3 N 4 dental implant restorations with personalized structures prepared by DLP technology have good mechanical properties and biocompatibility, which has great application potential in the future. [Display omitted] [ABSTRACT FROM AUTHOR]

Purpose To compare the absorbed dose from computed tomography (CT) in radiotherapy planning (RP-CT) against those from diagnostic CT (DG-CT) examinations and to explore the possible reasons for any dose differences. Method Two groups of patients underwent CT-scans of the thorax with either DG-CT (n = 55) or RP-CT (n = 55). Patients from each group had similar weight and body mass index (BMI) and were divided into low (<25) and high BMI (>25). Parameters including CTDIvol, DLP and scan-length were compared. Results The mean CTDIvol and DLP values from RP-CT (38.1 mGy, 1472 mGy cm) are approximately four times higher than for DG-CT (9.63 mGy, 376.5 mGy cm). For low BMI group, the CTDIvol in the RP-CT scans (36.4 mGy) is 6.3 times higher than the one in the DG-CT scans (5.8 mGy). For the high BMI group, the CTDIvol in the RP-CT (39.6 mGy) is 2.5 times higher than the one in the DG-CT scans (15.8 mGy). In the DG-CT scans a strong negative linear correlation between noise index (NI) and mean CTDIvol was observed (r = −0.954, p = 0.004); the higher NI, the lower CTDIvol. This was not the case in the RP-CT scans. Conclusion The absorbed radiation dose is significantly higher and less BMI dependent for RP-CT scans compared to DG-CT. Image quality requirements of the examinations should be researched to ensure that radiation doses are not unnecessarily high. [ABSTRACT FROM AUTHOR]

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CT scan room is a radiation working area. The Increasing workload in CT is subsequently increasing the risk of radiation hazards to the persons working around. We aim to evaluate protective barriers in the CT scan room at a Medical college, in Chitwan, Nepal. The total number of head and body scans and their corresponding CT-DLP values of a selected week were taken for the calculation of unshielded secondary air kerma at a 1m distance from the isocenter of the gantry. The distances of barriers from the isocenter of the gantry and their thickness were measured by measuring tape and Vernier caliper. The amount of unshielded air kerma at each barrier distance was calculated by inverse square law which was converted into transmission factors. Data were analyzed using an IBM SPSS 20 software. The thicknesses of lead and concrete were calculated from the standard graphs given by National Council on Radiation Protection and Measurements (NCRP). The necessary barrier thicknesses for console wall, corridor walls, reporting room wall, backyard wall, and ceiling were 190mm, 223mm,190mm,195mm,156mm, and 280mm of concrete respectively whereas for console room door, console room window and the entrance door were 2.00mm,2.09mm and1.53mm of lead equivalent respectively according to their transmission factors. The thicknesses of the console wall, corridor walls, reporting room wall, backyard wall, and ceiling present in the CT room were 280mm of concrete whereas the console room door, console room window, and entrance door were 2.00mm, 2.36mm, and 2.00mm of lead equivalent respectively. In short, the barriers in CT room have an equal or greater thickness than was necessary to stop hazardous radiation. The study showed that radiation shielding status of diagnostic CT scan room of CMCTH is adequate and there is no risk of radiation hazards. [ABSTRACT FROM AUTHOR]

Patients with congenital heart disease (CHD) are exposed to ionizing radiation at an early age through diagnostic and interventional procedures. While the largest radiation dose contribution is from cardiac catheterization procedures, other radiological examinations for investigation and follow-up might play a considerable role in the total radiation burden on this vulnerable population and influence possible late effects from radiation. To review a single institution's use of radiological non-catheterization examinations in selected CHD patients at different ages as input to the epidemiology project HARMONIC. 2,735 CHD patients sorted into age bins (Newborn: 0-0.25 years, 1-year-old: >0.25-2.5 years, 5-year-old: >2.5-7.5 years, 10-year-old: >7.5-12.5 years, 15-year-old: >12.5-17.5 years age, Adults: >17.5 years) during 2000-2020 are included. Examinations are categorized according to 'European Guidance on Estimating Population Doses from Medical X-Ray Procedures'. Examination and dose parameters are collected from the Institution's Radiology Information System. Radiation dose Indicators are dose-area product (DAP) and dose-length product (DLP). The most frequent X-ray examination was thoracic X-ray. About 3% of children had more than 10 thoracic X-ray. The mean DAP from each thoracic X-ray procedure was newborns- 2.34 (0.04-182 cGycm2), 1yr- 2.99 (0.1-567 cGycm2), 5yr- 4.13 (0.03-1075 cGycm2), 10yr- 9.64 (0.12-1804 cGycm2), 15yr- 12.93 (0.1-1942 cGycm2) and adults- 23.12 (3.5-190.24 cGycm2). CT thoracic was the most frequent. Around 10% of children had ≥ 2 thoracic CT. The mean DLP from each thoracic CT was newborns- 66.22 (13-241 mGycm), 1yr- 69.19 (4.46-334 mGycm), 5yr- 51.94 (3.8-193.81 mGycm), 10yr- 126.99 (13.15-1618 mGycm), 15yr- 179.01 (1.97-610 mGycm), and adults- 194.92 (113.3-341 mGycm). Cardiac angiography was the most frequent fluoroscopy/radiography examination. Nearly 10-20% of children had ≥ 2 cardiac angio. The mean DAP for each cardiac angio procedure was, newborns- 376.75 (1.35-1625 cGycm2), 1yr- 620.21 (2.13-9420 cGycm2), 5yr- 1121.18 (2.61-8517 cGycm2), 10yr- 2308.69 (24.89-29488 cGycm2), 15yr- 3651.64 (9.89-13072 cGycm2) and adults- 1880 cGycm2. Our results show that many of the patients in this vulnerable population undergo a substantial number of radiological examinations with a wide range of DAP/DLP values contributing to their cumulative radiation dose. The higher values of the dose indicator for some patients clearly imply that those patients receive very high doses and that could possibly lead to late effects. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: To establish current radiation dose levels with contemporary scanners capable of prospectively triggered or high-pitch spiral scan modes to previous generation scanners among patients evaluated for coronary artery disease, pulmonary embolism, aortic disease, and “triple rule out” in a large population of patients at multiple centers. Background: Previous small-scale studies with carefully controlled scan protocols report that CT scanners that facilitate prospectively triggered scanning and provide high-pitch spiral CT scan modes drastically lower radiation doses. However, diagnostic reference levels should be selected by medical bodies on the basis of large surveys of representative sites and reviewed at appropriate time intervals. Methods: Scan data including dose and image quality parameters were collected retrospectively from 64 slice scanners (control) and prospectively after sites installed 128-slice dual-source scanners with high-pitch capability (study). Protocol selection was purposely not specified to survey “real world” results. Blinded quantitative image analysis was performed on every fifth scan. Results: From April 2011 to March 2012, 2085 patients at 9 sites completed the study: 1051 coronary artery disease (509 control, 542 study), 528 pulmonary embolism (267 control, 261 study), 419 aortic disease (268 control, 151 study), and 87 triple rule out (53 control, 34 study). There was a significant reduction in median dose-length product (DLP) from 669 mGy∙cm (interquartile range [IQR]: 419–1026 mGy∙cm) in the control group to 260 mGy∙cm (IQR: 159–441 mGy∙cm) in the study group, a reduction by 61% (P < .0001) and was lower in all categories. No significant differences were noted in image quality. Conclusion: Use of advanced scanners facilitating prospectively triggered or high-pitch spiral scan modes results in marked dose reduction across a variety of cardiovascular studies, with no compromise in image quality. These findings may contribute to new target dose recommendations in societal guidelines. [Copyright &y& Elsevier]

Abstract: The DLP pocket projector can be classified into two parts according to design characteristic. One of them is illumination system. It composes of Red, Green and Blue LEDs. Each of them has a collimator to make lights illuminate dichroic filter collimated. By dichroic filters it combines three wavelengths lights together. The last part is the micro-lens array, condenser and TIR prism is used to illuminate DMD uniformly and reduce the size of illumination system. The other is imaging system. According to the standard of DMD; the angle of view, effective focal length, the relationship of imaging and object and imaging quality of the lens can be defined. By using optical simulation software, Code V and ZEMAX, the lens conform to the standards was well designed. Finally the tolerance of production was analysed. In this design, the average light efficiency of three wavelengths LED on DMD is 51.13%, and the average uniformity on DMD is 95.17%. About the screen, the average light efficiency is 44%, and the average uniformity is 87.3%. [Copyright &y& Elsevier]

Abstract: Helical scanning requires the irradiation of larger lengths than those planned. This is referred to as overscan and results to an increase of patient dose. Its impact on patient dose was investigated for three first generation multislice CT scanners; a six-, a quad- and a dual-slice. The amount of overscan was determined using the scanners’ dose-length product (DLP) indications and films positioned on the CT table. With the preset protocol for the chest examination selected in all CT scanners, the overscan length calculated from the DLP indications was 6.3, 3.5 and 2cm respectively, whereas the corresponding figures derived from the films were 6.6, 4.8 and 2.5 to 3.2cm. For a 30cm scan length, the respective contributions of overscan to the DLP values were 17, 10 and 6%, whereas for a scan length of 20cm the respective values increased to 24, 15 and 9%. For the smallest scan lengths allowed in helical mode, the respective contributions reached 53, 88 and 67% because for the six-slice scanner the smallest scan length was limited to twice the collimation, whereas in the quad and dual scanners no limitation existed. For small scan lengths the presence of overscan cancels out any dose reduction offered by helical scanning with pitch factor values larger than one and therefore the axial mode should be preferred, when this is not prohibited by the diagnostic task in question. [Copyright &y& Elsevier]

Abstract: Chemical imaging systems allow the visualisation of the distribution of chemical species on the sensor surface. This work represents a new flexible approach of read out in a light-addressable potentiometric sensor (LAPS) with the help of a digital light processing (DLP) set-up. The DLP, known well for video projectors, consists of a mirror-array MEMS device which allows fast and flexible generation of light patterns. With the help of these light patterns the sensor surface of the LAPS device can be read out sequentially in a raster like scheme (scanning LAPS). The DLP approach has several advantages compared to conventional scanning LAPS set-ups, e.g., the spot size, the shape and the intensity of the light pointer can be changed easily and no mechanical movement is necessary, which reduces the size of the set-up and increases the stability and speed of measurement. [ABSTRACT FROM AUTHOR]