Detecting Bombs in X-Ray Images of Hold Baggage: 2D Versus 3D Imaging

Objective: This study compared the visual inspection performance of airport security officers (screeners) when screening hold baggage with state-of-the-art 3D versus older 2D imaging. Background: 3D imaging based on computer tomography features better automated detection of explosives and higher baggage throughput than older 2D X-ray imaging technology. Nonetheless, some countries and airports hesitate to implement 3D systems due to their lower image quality and the concern that screeners will need extensive and specific training before they can be allowed to work with 3D imaging. Method: Screeners working with 2D imaging (2D screeners) and screeners working with 3D imaging (3D screeners) conducted a simulated hold baggage screening task with both types of imaging. Differences in image quality of the imaging systems were assessed with the standard procedure for 2D imaging. Results: Despite lower image quality, screeners’ detection performance with 3D imaging was similar to that with 2D imaging. 3D screeners revealed higher detection performance with both types of imaging than 2D screeners. Conclusion: Features of 3D imaging systems (3D image rotation and slicing) seem to compensate for lower image quality. Visual inspection competency acquired with one type of imaging seems to transfer to visual inspection with the other type of imaging. Application: Replacing older 2D with newer 3D imaging systems can be recommended. 2D screeners do not need extensive and specific training to achieve comparable detection performance with 3D imaging. Current image quality standards for 2D imaging need revision before they can be applied to 3D imaging.

A Faster Kind of Photojournalism?

This article examines factors influencing the editorial processing of photographs, the impact of photojournalistic practices on those processes as well as perceptions of images. Perspectives on visual gatekeeping and the news value of photographs were applied to a newsroom and interview study with a specific focus on photographs for the main news section of a Swedish newspaper. Findings identified routines, publication formats and resources as key factors, with some challenges posed by mobile publication formats and a focus on routine news. Photo editors were found to have a key function asserting expertise in a shared and interactive process. Yet changing routines and a reduced visual expertise on weekends were found to result in some lower image quality. While the ‘observed moment’ appeared to remain a photojournalistic ideal among visual gatekeepers, there were divergent perceptions found of the current and future functions of the news photograph.

AFOCAL SYSTEMS FORMED BY MIRROR OFF-AXIS PARABOLOID

Mirror systems make it possible to reduce device dimensions and its weight while preserving high input aperture and these systems are characterized by a number of other advantages. Their significant disadvantage is a central screening of an entrance pupil that leads to lower image quality. The paper contains description of the investigations on afocal systems formed by eccentrically cut-out mirror paraboloids (off-axis mirrors) where aperture diaphragm is displaced in the meridian plane for a defined value and a central field point is located on the optical axis. The canonic Mersenne systems are accepted as base schemas (modules) for these compositions. The paper considers two types of such systems: visible increases – Г > 0 and Г < 0. Algorithms for calculation of centered afocal systems with two and four reflections have been written in the paper and the systems are free from spherical aberration, coma, astigmatism when an input pupil is located in superimposed focal planes of all parabolic mirrors. An aberration in curvature image has been additionally corrected in three-mirror quart-parabolic scheme which is a combination of two classical telescopic Mersenne systems. The paper presents schemes and calculation results. Two-mirror schemes with non-screened input pupil have been studied in the paper and in this case all the system remains centered and an aperture diaphragm is decentered for the distance Cm which is commensurable with the diaphragm size. The paper contains description of the investigated afocal schemes with four reflections from off-axis mirror paraboloids, a prepared algorithm for calculation, the obtained formulas for making combination of canonic afocal systems formed by two mirrors. Computer simulation in software environment Opal and Zemax has been carried out in the paper. Basic description has been prepared while using two alternative methods for the class of decentered systems and aberration characteristics and schematic solutions for telescopic systems without screening with two and four reflections have been ob-tained in the paper. Two-mirror afocal systems with low-powered magnification are of some interest for practical application as accessories for registering object lenses.

Evaluation of MRI sequences for quantitative T1 brain mapping

T1 mapping constitutes a quantitative MRI technique finding significant application in brain imaging. It allows improved evaluation of contrast uptake, blood perfusion, volume, and provides more specific biomarkers of disease progression compared to conventional T1-weighted images. While there are many techniques for T1-mapping, there is also a wide range of reported T1-values in tissues, raising the issue of protocols’ reproducibility and standardization. The gold standard for obtaining T1-maps is based on acquiring IR-SE sequence. Widely used alternative sequences are IR-SE-EPI, VFA (DESPOT), DESPOT-HIFI and MP2RAGE that speed up scanning and fitting procedures. A custom MRI phantom was used to assess the reproducibility and accuracy of the different methods. All scans were performed using a 3T Siemens Prisma scanner. The acquired data were processed using two different codes. The main difference was observed for VFA (DESPOT) which grossly overestimated T1 relaxation time by 214 ms [CI: 126 270 ms] compared to the IR-SE sequence. MP2RAGE and DESPOT-HIFI sequences gave slightly shorter T1 than IR-SE (∼20 to 30ms) and can be considered as alternative and time-efficient methods for acquiring accurate T1 maps of the human brain, while IR-SE-EPI gave identical results, at a cost of a lower image quality.

THE EFFECT OF PANSHARPENING ALGORITHMS ON THE RESULTING ORTHOIMAGERY

This paper evaluates the geometric effects of pansharpening algorithms on automatically generated DSMs and thus on the resulting orthoimagery through a quantitative assessment of the accuracy on the end products. The main motivation was based on the fact that for automatically generated Digital Surface Models, an image correlation step is employed for extracting correspondences between the overlapping images. Thus their accuracy and reliability is strictly related to image quality, while pansharpening may result into lower image quality which may affect the DSM generation and the resulting orthoimage accuracy. To this direction, an iterative methodology was applied in order to combine the process described by Agrafiotis and Georgopoulos (2015) with different pansharpening algorithms and check the accuracy of orthoimagery resulting from pansharpened data. Results are thoroughly examined and statistically analysed. The overall evaluation indicated that the pansharpening process didn’t affect the geometric accuracy of the resulting DSM with a 10m interval, as well as the resulting orthoimagery. Although some residuals in the orthoimages were observed, their magnitude cannot adversely affect the accuracy of the final orthoimagery.

THE EFFECT OF PANSHARPENING ALGORITHMS ON THE RESULTING ORTHOIMAGERY

This paper evaluates the geometric effects of pansharpening algorithms on automatically generated DSMs and thus on the resulting orthoimagery through a quantitative assessment of the accuracy on the end products. The main motivation was based on the fact that for automatically generated Digital Surface Models, an image correlation step is employed for extracting correspondences between the overlapping images. Thus their accuracy and reliability is strictly related to image quality, while pansharpening may result into lower image quality which may affect the DSM generation and the resulting orthoimage accuracy. To this direction, an iterative methodology was applied in order to combine the process described by Agrafiotis and Georgopoulos (2015) with different pansharpening algorithms and check the accuracy of orthoimagery resulting from pansharpened data. Results are thoroughly examined and statistically analysed. The overall evaluation indicated that the pansharpening process didn’t affect the geometric accuracy of the resulting DSM with a 10m interval, as well as the resulting orthoimagery. Although some residuals in the orthoimages were observed, their magnitude cannot adversely affect the accuracy of the final orthoimagery.

Kualitas Citra Radiografi Berdasarkan Variasi Jeda Waktu Pembacaan Citra pada Computed Radiography

Background: Computed Radiography (CR) is imaging processor to digitize an image using imaging plate. Imaging plate can store latent image and should be read as soon as possible to avoid the loss of image quality. The longer storage time the lower image quality. This study aimed to determine the image quality in various image reading time delay.Methods: This iresearch was quantitative research with experimental approach. 5 images were acquired using step wedge as an object with same exposure factors. The imaging plates were read in five different image reading time delay variations (no-delay, 2 hours, 4 hours, 6 hours, and 8 hours after eksposure). Contrast and density of each image were measured using lgM and densitometer. Data were analyzed by comparing lgM, density, and contrast of each image.Result: The result showed that there were difference value in density, contrast, and lgM among no-delay, 2 hours, 4 hours, 6 hours, and 8 hours after eksposure images respectively. The average density were 0,701; 0,776; 0,772; 0,798; 0,791. The image contrast were 0,88; 1,09; 0,88; 1,06; 1,02. The lgM value were 2,42; 2,24; 2,21; 2,20; 2,19.Conclusion: The image quality was decreased over reading time delay, the longer reading time delay the lower image quality. To obtain the best image quality, the imaging plate should be read as soon as possible.

Myocardial Uptake of Technetium-99m-Furifosmin (Q12) Versus Technetiiim-99m-Sestamibi (MIBI)

Summary Aim: This study was performed to compare the myocardial uptake of Tc-99m-furifosmin (Q12) versus Tc-99m-sestamibi (MIBI) in correlation to the whole-body uptake under resting conditions. Methods: 21 patients with coronary artery disease and no rest ischemia were examined. A whole-body scan was performed 60 min. p.i. under resting conditions. A quantification of the uptake (whole-body, heart and right lung) was done by ROI technique. Results: The heart-to-lung ratio of Q12 (1.56 ± 0.191) was significantly lower as compared to MIBI (1.94 ± 0.197; p <0.01). In contrast, the heart-to-whole-body ratios (Q12 versus MIBI: 0.027 ± 0.012 versus 0.026 ± 0.004; p <0.76) did not differ. The lung-to-whole-body ratio (Q12 versus MIBI: 0.018 ± 0.009 versus 0.013 ± 0.002; p <0.17) were different, but did not reach significance. Conclusion: These data show that under resting conditions the total myocardial uptake of Q12 does not differ significantly from that of MIBI. However, the pulmonary uptake of Q12 is slightly higher, resulting in a significant lower heart-to-lung ratio. These findings imply a lower image quality of Q12 compared to MIBI.