| 1. |
- Reza, Salim, 1985-, et al.
(författare)
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Smart dosimetry by pattern recognition using a single photon counting detector system in time over threshold mode
- 2012
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- The function of a dosimeter is to determine the absorbed dose of radiation, for those cases in which, generally, the particular type of radiation is already known. Lately, a number of applications have emerged in which all kinds of radiation are absorbed and are sorted by pattern recognition, such as the Medipix2 application in [1]. This form of smart dosimetry enables measurements where not only the total dosage is measured, but also the contributions of different types of radiation impacting upon the detector surface. Furthermore, the use of a photon counting system, where the energy deposition can be measured in each individual pixel, ensures measurements with a high degree of accuracy in relation to the pattern recognition. In this article a Timepix [2] detector system has been used in the creation of a smart dosimeter for Alpha, Beta and Gamma radiation. When a radioactive particle hits the detector surface it generates charge clusters and those impacting upon the detector surface are read out and image processing algorithms are then used to classify each charge cluster. The individual clusters are calculated and as a result, the dosage for each type of radiation is given. In some cases, several particles can impact in roughly the same place, forming overlapping clusters. In order to handle this problem, a cluster separation method has been added to the pattern recognition algorithm. When the clusters have been separated, they are classified by shape and sorted into the correct type of radiation. The algorithms and methods used in this dosimeter have been developed so as to be simple and computationally effective, in order to enable implementation on a portable device. © 2012 IOP Publishing Ltd and SISSA.
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| 2. |
- Åhs, Fredrik, et al.
(författare)
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Medial prefrontal pathways for the contextual regulation of extinguished fear in humans
- 2015
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Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 122, s. 262-271
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Tidskriftsartikel (refereegranskat)abstract
- The maintenance of anxiety disorders is thought to depend, in part, on deficits in extinction memory, possibly due to reduced contextual control of extinction that leads to fear renewal. Animal studies suggest that the neural circuitry responsible fear renewal includes the hippocampus, amygdala, and dorsomedial (dmPFC) and ventromedial (vmPFC) prefrontal cortex. However, the neural mechanisms of context-dependent fear renewal in humans remain poorly understood. We used functional magnetic resonance imaging (fMRI), combined with psychophysiology and immersive virtual reality, to elucidate how the hippocampus, amygdala, and dmPFC and vmPFC interact to drive the context-dependent renewal of extinguished fear. Healthy human participants encountered dynamic fear-relevant conditioned stimuli (CSs) while navigating through 3-D virtual reality environments in the MRI scanner. Conditioning and extinction were performed in two different virtual contexts. Twenty-four hours later, participants were exposed to the CSs without reinforcement while navigating through both contexts in the MRI scanner. Participants showed enhanced skin conductance responses (SCRs) to the previously-reinforced CS + in the acquisition context on Day 2, consistent with fear renewal, and sustained responses in the dmPFC. In contrast, participants showed low SCRs to the CSs in the extinction context on Day 2, consistent with extinction recall, and enhanced vmPFC activation to the non-reinforced CS -. Structural equation modeling revealed that the dmPFC fully mediated the effect of the hippocampus on right amygdala activity during fear renewal, whereas the vmPFC partially mediated the effect of the hippocampus on right amygdala activity during extinction recall. These results indicate dissociable contextual influences of the hippocampus on prefrontal pathways, which, in turn, determine the level of reactivation of fear associations.
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| 3. |
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| 4. |
- Xie, Yang, et al.
(författare)
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Cervical Spondylosis Diagnosis Based on Convolutional Neural Network with X-ray Images
- 2024
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 24:11
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Tidskriftsartikel (refereegranskat)abstract
- The increase in Cervical Spondylosis cases and the expansion of the affected demographic to younger patients have escalated the demand for X-ray screening. Challenges include variability in imaging technology, differences in equipment specifications, and the diverse experience levels of clinicians, which collectively hinder diagnostic accuracy. In response, a deep learning approach utilizing a ResNet-34 convolutional neural network has been developed. This model, trained on a comprehensive dataset of 1235 cervical spine X-ray images representing a wide range of projection angles, aims to mitigate these issues by providing a robust tool for diagnosis. Validation of the model was performed on an independent set of 136 X-ray images, also varied in projection angles, to ensure its efficacy across diverse clinical scenarios. The model achieved a classification accuracy of 89.7%, significantly outperforming the traditional manual diagnostic approach, which has an accuracy of 68.3%. This advancement demonstrates the viability of deep learning models to not only complement but enhance the diagnostic capabilities of clinicians in identifying Cervical Spondylosis, offering a promising avenue for improving diagnostic accuracy and efficiency in clinical settings.
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| 5. |
- Allahgholi, Aschkan, et al.
(författare)
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The Adaptive Gain Integrating Pixel Detector at the European XFEL
- 2019
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Ingår i: Journal of Synchrotron Radiation. - 0909-0495 .- 1600-5775. ; 26, s. 74-82
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Tidskriftsartikel (refereegranskat)abstract
- The Adaptive Gain Integrating Pixel Detector (AGIPD) is an X-ray imager, custom designed for the European X-ray Free-Electron Laser (XFEL). It is a fast, low-noise integrating detector, with an adaptive gain amplifier per pixel. This has an equivalent noise of less than 1keV when detecting single photons and, when switched into another gain state, a dynamic range of more than 10(4)photons of 12keV. In burst mode the system is able to store 352 images while running at up to 6.5MHz, which is compatible with the 4.5MHz frame rate at the European XFEL. The AGIPD system was installed and commissioned in August 2017, and successfully used for the first experiments at the Single Particles, Clusters and Biomolecules (SPB) experimental station at the European XFEL since September 2017. This paper describes the principal components and performance parameters of the system.
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| 6. |
- Björkstrand, Johannes, et al.
(författare)
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Disrupting Reconsolidation Attenuates Long-Term Fear Memory in the Human Amygdala and Facilitates Approach Behavior
- 2016
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 26:19, s. 2690-95
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Tidskriftsartikel (refereegranskat)abstract
- Memories become labile and malleable to modification when recalled [1]. Fear-conditioning experiments in both rodents and humans indicate that amygdala-localized short-term fear memories can be attenuated by disruption of their reconsolidation with extinction training soon after memory activation [2-7]. However, this may not be true for natural long-term fears. Studies in rodents indicate that although it is possible to disrupt the reconsolidation of older memories [8-11], they appear to be more resistant [1, 3, 9, 12, 13]. In humans, 1-week-old conditioned fear memories have been attenuated by behaviorally induced disruption of reconsolidation [14], but it remains to be seen whether this is possible for naturally occurring long-term fears and whether the underlying neural mechanisms are similar to those found in experimental fear-conditioning paradigms. Using functional brain imaging in individuals with a lifelong fear of spiders, we show that fear memory activation followed by repeated exposure to feared cues after 10 min, which disrupts reconsolidation, attenuates activity in the basolateral amygdala at re-exposure 24 hr later. In contrast, repeated exposure 6 hr after fear memory activation, which allows for reconsolidation, did not attenuate amygdala activity. Disrupted, but not undisrupted, reconsolidation facilitated approach behavior to feared cues, and approach behavior was inversely related to amygdala activity during re-exposure. We conclude that memory activation immediately preceding exposure attenuates the neural and behavioral expression of decades-old fear memories and that, similar to experimentally induced fear memories, the basolateral amygdala is crucially involved in this process.
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| 7. |
- Nie, Yali, et al.
(författare)
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Recent Advances in Diagnosis of Skin Lesions using Dermoscopic Images based on Deep Learning
- 2022
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Ingår i: IEEE Access. - 2169-3536. ; 10, s. 95716-95747
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Tidskriftsartikel (refereegranskat)abstract
- Skin cancer is one of the most threatening cancers, which spreads to the other parts of the body if not caught and treated early. During the last few years, the integration of deep learning into skin cancer has been a milestone in health care, and dermoscopic images are right at the center of this revolution. This review study focuses on the state-of-the-art automatic diagnosis of skin cancer from dermoscopic images based on deep learning. This work thoroughly explores the existing deep learning and its application in diagnosing dermoscopic images. This study aims to present and summarize the latest methodology in melanoma classification and the techniques to improve this. We discuss advancements in deep learning-based solutions to diagnose skin cancer, along with some challenges and future opportunities to strengthen these automatic systems to support dermatologists and enhance their ability to diagnose skin cancer. Author
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| 8. |
- Brombal, Luca, et al.
(författare)
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Edge-illumination spectral phase-contrast tomography
- 2024
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 69:7
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Tidskriftsartikel (refereegranskat)abstract
- Following the rapid, but independent, diffusion of x-ray spectral and phase-contrast systems, this work demonstrates the first combination of spectral and phase-contrast computed tomography (CT) obtained by using the edge-illumination technique and a CdTe small-pixel (62 mu m) spectral detector. A theoretical model is introduced, starting from a standard attenuation-based spectral decomposition and leading to spectral phase-contrast material decomposition. Each step of the model is followed by quantification of accuracy and sensitivity on experimental data of a test phantom containing different solutions with known concentrations. An example of a micro CT application (20 mu m voxel size) on an iodine-perfused ex vivo murine model is reported. The work demonstrates that spectral-phase contrast combines the advantages of spectral imaging, i.e. high-Z material discrimination capability, and phase-contrast imaging, i.e. soft tissue sensitivity, yielding simultaneously mass density maps of water, calcium, and iodine with an accuracy of 1.1%, 3.5%, and 1.9% (root mean square errors), respectively. Results also show a 9-fold increase in the signal-to-noise ratio of the water channel when compared to standard spectral decomposition. The application to the murine model revealed the potential of the technique in the simultaneous 3D visualization of soft tissue, bone, and vasculature. While being implemented by using a broad spectrum (pink beam) at a synchrotron radiation facility (Elettra, Trieste, Italy), the proposed experimental setup can be readily translated to compact laboratory systems including conventional x-ray tubes.
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| 9. |
- Tourancheau, Sylvain, 1982-, et al.
(författare)
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Evaluation of quality of experience in interactive 3D visualization: methodology and results
- 2012
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE - International Society for Optical Engineering. - 9780819489357 ; , s. Art. no. 82880O-
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Konferensbidrag (refereegranskat)abstract
- Human factors are of high importance in 3D visualization, but subjective evaluation of 3D displays is not easy because of a high variability among users. This study aimed to evaluate and compare two different 3D visualization systems (a market stereoscopic display, and a state-of-the-art multi-view display) in terms of task performance and quality of experience (QoE), in the context of interactive visualization. An adapted methodology has been designed in order to focus on 3D differences and to reduce the influence of all other factors. 36 subjects took part in an experiment during which they were asked to solve different tasks in a synthetic 3D scene. After the experiment, they were asked to judge the quality of their experience, according to specific features. Results showed that scene understanding and precision was significantly better on the multi-view display. Concerning the quality of experience, visual comfort was judged significantly better on the multi-view display and visual fatigue was reported by 52% of the subjects on the stereoscopic display. This study has permitted to identify some factors influencing QoE such as prior experience and stereopsis threshold.
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| 10. |
- Rezasson, Reza, 1985-, et al.
(författare)
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A fast and non-destructive alternative to the burnout method for paperboard quality inspections using phase-contrast X-ray imaging
- 2023
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Ingår i: TAPPI Journal. - : TAPPI. - 0734-1415. ; 22:2, s. 99-106
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Tidskriftsartikel (refereegranskat)abstract
- An X-ray based quality inspection method for paperboard was implemented and tested as a fastand non-destructive alternative to the burnout method. An argument against X-ray imaging for inspection of paperand paperboard has been that X-ray absorption is low in paper. To overcome this limitation, we used phase-contrastX-ray imaging (PCXI), which gives higher contrast than conventional attenuation-based imaging for low-absorbingmaterials such as paper. The suggested PCXI method was applied to previously prepared and quality rated samplesusing the burnout method.A strong similarity between the burnout images and the PCXI images was observed. In conclusion, further devel-opment of the phase-contrast X-ray method would provide an interesting option for replacing or complementing thestandard burnout method.
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