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We propose a web‐based collaborative CAD system allowing for the remote communication and data exchange between radiologists and researchers in computer vision‐based software engineering. The proposed web‐based interface is implemented in the Java Advanced Imaging Application Programming Interface. The different modules of the interface allow for 3D and 2D data visualization, as well as for the parametric adjustment of 3D reconstruction process. The proposed web‐based CAD system was tested in a pilot study involving a limited number of liver cancer cases. The successful system validation in the feasibility stage will lead to an extended clinical study on CT and MR image databases. [ABSTRACT FROM AUTHOR]

This paper presents a newly developed method to estimate, in magnetic resonance (MR) images, the temperatures reached within the volume of an iceball produced by a cryogenic probe. Building on the direct measurements of the MR signal intensity and its correlation with independent temperature variations at the phase transition from liquid to solid, the thermal information embedded in the images was accessed. The volume and diameter of the growing iceball were estimated from a time series of MR images. Using regressions over the volume in the time and thermal domains, this method predicted the cryogenic temperatures beyond the range of sensitivity of the MR signal itself. We present a validation of this method in samples of gelatin and ex vivo pig liver. Temperature predictions are shown to agree with independent thermosensor readings over a range extending from 20 °C down to -- 65 °C, with an average error of less than 6 °C. [ABSTRACT FROM AUTHOR]

Many tasks, such as pose determination, object recognition and model building rely on a geometrical description of the visible surfaces derived from scene measurements. Even though much effort has been invested in surface description, robust extraction of surface parameters from scattered and noisy 3-D measurements is still a delicate task. For a given visible surface section, the extracted parameters should not depend on the sensor position in the scene nor on a particular measurement set on this surface. In this work, we show that a viewpoint invariant and stable local surface description can be extracted on sections where measurement constraints are redundant with respect to a polynomial model. A segmentation approach is developed to identify such stable sections. The approach is based on a measurement error model which takes into account the sensor's viewpoint. An application of the approach to the extraction of straight line sections from single scan 3-D surface profiles is presented. The extracted stable linear sections are stored in a list that includes the estimated descriptive parameters for each section and indices of reliability for each description. The descriptive parameters obtained from images of the objects is compared with pre-measured parameters. [ABSTRACT FROM AUTHOR]

Objectives In the context of the 100th anniversary celebrations of the Hôpital en santé mentale Albert-Prévost, the present article retraces the history of this pioneering institution in the provision of psychiatric care in the province of Québec. Methods Multiple psychiatrists and health-care professionals who once worked or are still working at Albert-Prévost were interviewed to record their recollection of how psychiatric care was delivered as knowledge about mental illness progressed and how different defining historical events concerning the administration of this institution unfolded. Private and public archives as well as articles documenting the history of this institution were consulted in order to contextualize the participants' experiences. Results A brief exploration of the historical and political context that led to the creation of the Sanatorium Albert-Prévost is provided. The key administrative, political and sociological issues are described at each critical period as well as the interplay between the growing knowledge base about the causes and treatments of psychiatric problems and different models of provision of care as different generations of clinicians search for an optimal practice and organisation of care. It's triple mission of care, teaching and research is described. Conclusion The Hôpital en santé mentale Albert-Prévost has contributed in a significant manner in the shaping of mental health care provision in Québec and several physicians and other health care professionals who have worked there, throughout the past century, have been key contributors to the social, educational, cultural and political advances in this province.

This work addresses the problem of automatic head pose estimation and its application in 3D gaze estimation using low quality RGB-D sensors without any subject cooperation or manual intervention. The previous works on 3D head pose estimation using RGB-D sensors require either an offline step for supervised learning or 3D head model construction, which may require manual intervention or subject cooperation for complete head model reconstruction. In this paper, we propose a 3D pose estimator based on low quality depth data, which is not limited by any of the aforementioned steps. Instead, the proposed technique relies on modeling the subject's face in 3D rather than the complete head, which, in turn, relaxes all of the constraints in the previous works. The proposed method is robust, highly accurate and fully automatic. Moreover, it does not need any offline step. Unlike some of the previous works, the method only uses depth data for pose estimation. The experimental results on the Biwi head pose database confirm the efficiency of our algorithm in handling large pose variations and partial occlusion. We also evaluated the performance of our algorithm on IDIAP database for 3D head pose and eye gaze estimation.

Purpose: In permanent seed implants, 60 to more than 100 small metal capsules are inserted in the prostate, creating artifacts in x-ray computed tomography (CT) imaging. The goal of this work is to develop an automatic method for metal artifact reduction (MAR) from small objects such as brachytherapy seeds for clinical applications., Methods: The approach for MAR is based on the interpolation of missing projections by directly using raw helical CT data (sinogram). First, an initial image is reconstructed from the raw CT data. Then, the metal objects segmented from the reconstructed image are reprojected back into the sinogram space to produce a metal-only sinogram. The Steger method is used to determine precisely the position and edges of the seed traces in the raw CT data. By combining the use of Steger detection and reprojections, the missing projections are detected and replaced by interpolation of non-missing neighboring projections., Results: In both phantom experiments and patient studies, the missing projections have been detected successfully and the artifacts caused by metallic objects have been substantially reduced. The performance of the algorithm has been quantified by comparing the uniformity between the uncorrected and the corrected phantom images. The results of the artifact reduction algorithm are indistinguishable from the true background value., Conclusions: An efficient algorithm for MAR in seed brachytherapy was developed. The test results obtained using raw helical CT data for both phantom and clinical cases have demonstrated that the proposed MAR method is capable of accurately detecting and correcting artifacts caused by a large number of very small metal objects (seeds) in sinogram space. This should enable a more accurate use of advanced brachytherapy dose calculations, such as Monte Carlo simulations.

We propose a web-based collaborative CAD system allowing for the remote communication and data exchange between radiologists and researchers in computer vision-based software engineering. The proposed web-based interface is implemented in the Java Advanced Imaging Application Programming Interface. The different modules of the interface allow for 3D and 2D data visualization, as well as for the parametric adjustment of 3D reconstruction process. The proposed web-based CAD system was tested in a pilot study involving a limited number of liver cancer cases. The successful system validation in the feasibility stage will lead to an extended clinical study on CT and MR image databases.