Magnus Uppsäll

Land mine detection by IR temporal analysis: physical numerical modeling

The overall objective of this paper is to improve the understanding of thermodynamic mechanisms around buried objects. The purpose is to utilize most favourable conditions for detection and also to enhance and evaluate other detection methods shown in a companion paper. This paper focuses on physical based models and simulations with measured data as boundaries for different situations of buried objects. For numerical models some assumptions of the real environment and boundaries have to be made, this paper shows the effects of different approaches of these assumptions. The investigations are carried out using a FEM approach with measured weather data as well as different sub models for the boundaries. All modelling works are carried out very in close connections with experiments with the purpose to achieve high accordance between measured and simulated values. This paper shows experimental and simulated results and discusses also the temporal analysis of thermal IR data.

Land mine detection by IR temporal analysis: detection method

The Swedish Defence Research Agency (FOI) has presented several approaches to temporal analysis of thermal IR data in the application of mine detection during the years. Detection by classification is performed using a number of detection algorithms with varying, in general good, results. The FOI temporal analysis method is tested on images randomly chosen from a diurnal sequence. The test sequence show very little contrast. The reference features are taken from a known object in the scene or from a numerical model of the object of interest. In this paper variations of the method are evaluated on the same test data. Focus is on the question if increased number of data collection times affects the detection rate and false alarm rate. The ROC curves show performance better than random for all of the tested cases, and excellent for some. Detection rate increases and false alarm rate decreases with increased number of images used for some of the tested cases.

Temporal method for IR minefield feature detection

The overall objective of this work is to investigate the possibilities of using airborne IR sensors for the purpose of detecting minefield features, such as land mines. A method is proposed for temporal analysis by extracting relevant information from diurnal IR images utilizing a combination of thermodynamic modelling, signal and image processing. This paper presents results from a field test of level 2 survey in May 2003 of suspected mine-polluted areas in Croatia. Airborne data was acquired using an IR sensor mounted on a rotary wing UAV. A weather station was used to collect weather data, and pt-100 temperature sensors recorded the temperature gradient in the soil and in reference markers that were used for calibrating the IR camera. The proposed method compares simulated temporal temperature with image data collected at several times during a diurnal cycle from the same area, pixel by pixel. The images are co-registered and calibrated with respect to reference values. The numerical model is based on physical laws and is set with relevant properties, geometries, materials, surface coefficients and the influence of the actual weather sets the boundary conditions. This paper shows some results from using temporal features for detection of different relevant objects in a real minefield.

Temporal IR contrast variation of buried land mines

This paper presents the work on the detection of land mines using IR-images. Experiments have been performed where outdoor time series of IR contrast have been measured for wax filled antitank mines in sand and for real mines in a gravel road. For antitank mines in the sand box the contrast dependence of time lap between burial and measurement has been analyzed for a period of four months. The diurnal contrast variation of an anti tank mine buried for two and a half year in a gravel road has been calculated. Statistical correlation between apparent temperatures and weather parameters for different cases have been calculated. The purpose is to understand the origin of the contrast and to be able to predict the contrast at different times and under different conditions.

Thermal Effects On Solar Radiated Sand SurfacesContaining Landmines — A Heat Transfer Analysis

This paper reports on the possibility of modelling thermal effects for detecting mines using infrared imaging systems. Results from experiments made in an indoor test landscape, using a sandbox and a solar panel with measuring instruments, are compared to simulated data from a heat transfer model. The radiation from the panel was varied in order to resemble the solar variation from sunrise to sunset. The different temperatures of the sand surface, the sand at different depths and on the surfaces of the four generic mines were sampled at one-minute intervals throughout the experiments. Infrared cameras working in the 2-5 p.m and 8-12 jam bands were used in order to record images of the sand surface. The camera system calculates the apparent temperature of selected areas of the images based on the detected radiation The simulation was carried out using the Finite Element Method. The sequences of the infrared images show the variation in emitted radiation as the irradiation of the surface is varied. There are two different phenomenon dominating the two wavelength bands In 2-5 p.m region there is a reflecting dominance and in the 8-12 p.m region the radiation originates mainly from emission. The simulation shows good agreement with the experimental result for the depth profile, where the temperatures were studied along a vertical line through the centre of the mine, as well as for the surface temperature

Real-time intraoperative visualization of myocardial circulation by augmented reality temperature display

Abstracts of the 22 International Conference of the Society for Medical Innovation and Technology (SMIT), 2-4 September 2010, Trondheim, Norways of the 22 International Conference of the Society for Medical Innovation and Technology (SMIT), 2-4 September 2010, Trondheim, Norway Abstracts appear in alphabetical order according to title. An (O) or (P) after the titles appear in alphabetical order according to title. An (O) or (P) after the title indicate respectively whether the abstract was accepted for an oral or poster session. 1. 2D/3D Registration of Ultrasound and Fluoroscopy: is image preprocessing useful? (O) Pascal Fallavollita, School of Computing, Queen’s University, Canada Zahra KarimAghaloo, McGill University Clif Burdette, Acoustic MedSystems Inc. Danny Song, Johns Hopkins Hospital Purang Abolmaesumi, University of British Columbia Gabor Fichtinger, Queen’s University Motivation: In prostate brachytherapy, transrectal ultrasound (TRUS) is used to visualize the anatomy, while implanted seeds can be seen in C-arm fluoroscopy. Intra-operative dosimetry optimization requires reconstruction of the implanted seeds from multiple C-arm fluoroscopy images, which in turn requires estimation of the C-arm poses. We proposed to estimate the relative pose of C-arm images by the registration of the 2D fluoroscopy images to the 3D TRUS volume, and by doing so we estimate the poses of C-arm images in a coordinate system fixed to the prostate. This paper investigates whether preprocessing the TRUS images increases registration performance. Methodology: We implemented 7 different filters for the TRUS volume to investigate whether image pre-processing is a requirement. The baseline for comparison is no filtering (US-0). US-1 is a noise reduction filter based on two successive thresholdings. US-2 is a phase congruency filter. The beam profile filter (US-3) accounts for the finite thickness of the ultrasound beam and the focusing in the elevational and lateral directions. In US-4, we combine parallel noise reduction, phase congruency and beam profile filters in a Bayesian model. In US-5 noise reduction is followed by phase congruency. In US-6, noise reduction is followed by beam profile filtering. Finally, in US-7 we cascade noise reduction, phase congruency, and beam profile filtering. Experiments and Results: A commercial phantom was implanted with seeds and imaged with TRUS and CT. Ground-truth registration was established between the two modalities by fiducials. Synthetic ground-truth fluoro images were created from the CT volume and registered to the 3D TRUS using normalized correlation metric. The US-0 baseline provided best results for pose estimation: the average rotation and translation errors were 1.1 ± 1.2 and 1.1 ± 0.6 mm. The US-6 filter followed with average rotation and translation errors of 3.1 ± 3.9 and 3.2 ± 3.4 mm. In human patient data, the measured registration error compared to the manually selected seed locations by the clinician was 2.86 ± 1.26 mm when not filtering TRUS. Conclusion: Fully automated image-based C-arm pose estimation was demonstrated in prostate brachytherapy where accuracy and robustness was excellent on phantom andadequate in human patient data. We conclude that pre-processing of the TRUS images did not yield significant improvement in the process. 2. 3D needle guidance with cone-beam ct: results in 41 patients suspected of renal malignancy (O) Harm Van Melick, St. Antonius hospital, Nieuwegein, dept. of urology, the Netherlands Sicco Braak, St. Antonius hospital, Nieuwegein, dept. of radiology Mircea Onaca, St. Antonius hospital, Nieuwegein, dept. of urology Christiaan van Swol, St. Antonius hospital, Nieuwegein, dept. of clinical physics Marco van Strijen, St. Antonius hospital, Nieuwegein, dept. of radiology Background: The incidence of renal tumors is rising, mostly by the increase of abdominal imaging. Many of ISSN 1364-5706 print/ISSN 1365-2931 online 2010 Informa Healthcare DOI: 10.3109/13645706.2010.500867 M in im I nv as iv e T he r A lli ed T ec hn ol D ow nl oa de d fr om in fo rm ah ea lth ca re .c om b y T ec hn ic al U ni ve rs ity o f E in dh ov en o n 11 /0 1/ 10 Fo r pe rs on al u se o nl y. these tumors are small asymptomatic renal masses, less than 4 cm in diameter. Small tumors are less often malignant. This increases the indication for renal biopsies. The standard procedure for renal biopsies is image-guided biopsy with help of ultrasound or CT. These procedures possess several restrictions. Not all lesions are good visible on ultrasound and the use of CT is limited in some lesions. Purpose: XperGuide is a new real-time needle guidance technique that uses cone-beamCT and fluoroscopy in an angiosuite. This prospective study presents data of XperGuide biopsies in lesions suspected for renal carcinoma.Method: XperGuide uses a rotating flat panel detector (Philips Medical Systems) that creates a 3D CT image. A safe needle tract is determined within this reconstructed volume, avoiding essential anatomic structures. The information of the needle tract from the cone-beamCT is fused with real-time fluoroscopy. In this way accurate needle guidance is accomplished and coaxial 18 gauge biopsies are taken. XperGuide makes it easier to biopsy at sharper angles than in conventional CT-guided biopsies. Patients with an indication for renal biopsy because of suspected malignancy were selected for XperGuide biopsy if ultrasound-guided biopsy was technically not possible ornotsafe.Results:BetweenOctober2006andJanuary 2010 a total of 41 patients (average age 61.9 years) underwent 43 procedures. These 43 biopsies resulted in24malignancies (56%),14benign lesions (33%)and 5 specimens (11%) could not be classified. Two of the latter lesions proofed to be renal cell carcinoma during follow-up. The 3 other unclassified lesions did not show significant increase in size during an average follow-up of 13 months. Average target diameter was 25.4 mm (range 10-68 mm) and the average number of biopsies taken per procedure was 3.6 (range 3-6). Radiation dose seams to be less than in similar CT-guided procedures. There were 2 minor bleeding complications that could be treated using absorbable haemostatic material. Conclusion: XperGuide is a safe and adequate technique to biopsy renal tumors. Biopsies can be taken in locations that were formerly hard to reach and in situations when ultrasound visibility is unsatisfactory. 3. 4D-Imaging of voluntary joint motion from bi-plane fluoroscopy images (O) Geert Streekstra, Remmet Jonges, Academic Medical Center, Amsterdam, The Netherlands Bart Carelsen, Philips Healthcare, Best, The Netherlands Kees Grimbergen, Simon Strackee, Academeic Medical Center, Amsterdam, The Netherlands Background: To understand the functioning of the wrist joint, the availability of dynamic 3D motion patterns (i.e. 4D-Imaging) of the carpal bones is essential. 3D motion patterns of carpal bones and dynamic joint space measurement during voluntary motion are potentially useful for patients with dynamic joint problems. Purpose: Current methods are capable of imaging 3D motion patterns of carpal bones by forced motion of the hand. A drawback of these methods is that a forced motion limits the freedom in choosing diagnostic motion protocols. Therefore we propose imaging of 3D dynamic motion patterns of carpal bones during voluntary motion of the hand based on bi-plane video fluoroscopy images. Method and materials: For acquisition of bi-plane video fluoroscopy images we used the Alura FD20/10 of Philips. During voluntary motion of the hand, video fluoroscopy time series of two flat panel detectors are simultaneously acquired. Additionally, a CT scan of the wrist is acquired from which radius, ulna and the carpal bones are segmented. By combination of the segmented CT scan and the biplane video fluoroscopy series, the three translation and three rotation parameters of each of the 15 bones are obtained. The feasibility of the method in vivo was evaluated by measuring joint space as a function of the pose of the hand during voluntary motion of the hand in healthy subjects and in a patient with SL dissociation. Results: Experiments on a cadaver specimen reveal that the precision is 0.05 mm for translations and 0.42 degrees for rotations. The in vivo experiments reveal that the 3D motion patterns differ substantially between healthy subjects and the SLpatient. Moreover, in healthy subjects the minimal joint space is virtually independent of the hand pose (1 mm) whereas the joint space varies substantially with the hand pose for the SL-patient (1-3 mm). Conclusion: Precise estimation of translations and rotation parameters of carpal bones as well as time dependent measurement of joint space can be achieved using dynamic bi-plane video fluoroscopy time series. 4. A field mapping technique for estimation of BOLD sensitivity in fmri (O) Anne-Lene Mathisen, University of Oslo, Physics Dept. and Interventional Centre, Oslo University Hospital, Oslo, Norway Atle Bjørnerud, University of Oslo, Physics Dept. and Interventional Centre, Oslo University Hospital, Oslo, Norway Frédéric Courivaud, Interventional Centre, Oslo University Hospital, Oslo, Norway 10 Abstracts M in im I nv as iv e T he r A lli ed T ec hn ol D ow nl oa de d fr om in fo rm ah ea lth ca re .c om b y T ec hn ic al U ni ve rs ity o f E in dh ov en o n 11 /0 1/ 10 Fo r pe rs on al u se o nl y. Background: Functional magnetic resonance imaging (fMRI) based on blood oxygen level dependent (BOLD) contrast is today a very useful tool in the field of neurological research. However, the presence of magnetic susceptibility difference in the brain, which creates local field inhomogeneity, can compromise the ability to detect the BOLD effect. These susceptibility differences arise typically near tissuesair interface or in the presence or surgical clips in the skull. Significant artefacts occurs in these regions when using Gradient E

Multi-optical mine detection: results from a field trial

As a part of the Swedish mine detection project MOMS, an initial field trial was conducted at the Swedish EOD and Demining Centre (SWEDEC). The purpose was to collect data on surface-laid mines, UXO, submunitions, IEDs, and background with a variety of optical sensors, for further use in the project. Three terrain types were covered: forest, gravel road, and an area which had recovered after total removal of all vegetation some years before. The sensors used in the field trial included UV, VIS, and NIR sensors as well as thermal, multi-spectral, and hyper-spectral sensors, 3-D laser radar and polarization sensors. Some of the sensors were mounted on an aerial work platform, while others were placed on tripods on the ground. This paper describes the field trial and the presents some initial results obtained from the subsequent analysis.

Spatial modeling of occlusion patterns applied to the detection of surface-laid mines

Images recorded in ground areas potentially containing surface laid land mines are considered. The first hypothesis is that the image is of clutter (grass) only, while the alternative is that the image contains a partially occluded (covered) land mine in addition to the clutter. In such a scenario, the occlusion pattern is unknown and has to be treated as a nuisance parameter. In a previous paper it was shown that deterministic treatment of the unknown occlusion pattern, in companion with the applied model, renders a substantial increase in detector performance as compared to employment of the traditional additive model. However, a deterministic assumption ignores possible correlation and additional gains could be possible by taking the spatial properties into account. In order to incorporate knowledge regarding the occlusion, the spatial distribution is characterized in terms of an underlying Markov Random Field (MRF) model. A major concern with MRF models is their complexity. Therefore, in addition to this, a less computationally demanding technique to accommodate the occlusion behavior is also proposed. The main purpose of this paper is to investigate if significant gains are possible by acknowledging the spatial dependence. Evaluation on data using real occluded targets however indicates that the gain seem to be marginal.