464 research outputs found
Computer- and robot-assisted Medical Intervention
Medical robotics includes assistive devices used by the physician in order to
make his/her diagnostic or therapeutic practices easier and more efficient.
This chapter focuses on such systems. It introduces the general field of
Computer-Assisted Medical Interventions, its aims, its different components and
describes the place of robots in that context. The evolutions in terms of
general design and control paradigms in the development of medical robots are
presented and issues specific to that application domain are discussed. A view
of existing systems, on-going developments and future trends is given. A
case-study is detailed. Other types of robotic help in the medical environment
(such as for assisting a handicapped person, for rehabilitation of a patient or
for replacement of some damaged/suppressed limbs or organs) are out of the
scope of this chapter.Comment: Handbook of Automation, Shimon Nof (Ed.) (2009) 000-00
Medical robotics: where we come from, where we are and where we could go
This short note presents a viewpoint about medical robotics
Atlas-Based Prostate Segmentation Using an Hybrid Registration
Purpose: This paper presents the preliminary results of a semi-automatic
method for prostate segmentation of Magnetic Resonance Images (MRI) which aims
to be incorporated in a navigation system for prostate brachytherapy. Methods:
The method is based on the registration of an anatomical atlas computed from a
population of 18 MRI exams onto a patient image. An hybrid registration
framework which couples an intensity-based registration with a robust
point-matching algorithm is used for both atlas building and atlas
registration. Results: The method has been validated on the same dataset that
the one used to construct the atlas using the "leave-one-out method". Results
gives a mean error of 3.39 mm and a standard deviation of 1.95 mm with respect
to expert segmentations. Conclusions: We think that this segmentation tool may
be a very valuable help to the clinician for routine quantitative image
exploitation.Comment: International Journal of Computer Assisted Radiology and Surgery
(2008) 000-99
BiopSym: a simulator for enhanced learning of ultrasound-guided prostate biopsy
This paper describes a simulator of ultrasound-guided prostate biopsies for
cancer diagnosis. When performing biopsy series, the clinician has to move the
ultrasound probe and to mentally integrate the real-time bi-dimensional images
into a three-dimensional (3D) representation of the anatomical environment.
Such a 3D representation is necessary to sample regularly the prostate in order
to maximize the probability of detecting a cancer if any. To make the training
of young physicians easier and faster we developed a simulator that combines
images computed from three-dimensional ultrasound recorded data to haptic
feedback. The paper presents the first version of this simulator
Biopsym : a learning environment for transrectal ultrasound guided prostate biopsies
This paper describes a learning environment for image-guided prostate
biopsies in cancer diagnosis; it is based on an ultrasound probe simulator
virtually exploring real datasets obtained from patients. The aim is to make
the training of young physicians easier and faster with a tool that combines
lectures, biopsy simulations and recommended exercises to master this medical
gesture. It will particularly help acquiring the three-dimensional
representation of the prostate needed for practicing biopsy sequences. The
simulator uses a haptic feedback to compute the position of the virtual probe
from three-dimensional (3D) ultrasound recorded data. This paper presents the
current version of this learning environment
Short-term memory effects of an auditory biofeedback on isometric force control: Is there a differential effect as a function of transition trials?
The aim of the present study was to investigate memory effects, force
accuracy, and variability during constant isometric force at different force
levels, using auditory biofeedback. Two types of transition trials were used: a
biofeedback-no biofeedback transition trial and a no biofeedback-biofeedback
transition trial. The auditory biofeedback produced a low- or high-pitched
sound when participants produced an isometric force lower or higher than
required, respectively. To achieve this goal, 16 participants were asked to
produce and maintain two different isometric forces (305% and 90N5%)
during 25s. Constant error and standard deviation of the isometric force were
calculated. While accuracy and variability of the isometric force varied
according to the transition trial, a drift of the force appeared in the no
biofeedback condition. This result suggested that the degradation of
information about force output in the no biofeedback condition was provided by
a leaky memory buffer which was mainly dependent on the sense of effort.
Because this drift remained constant whatever the transition used, this memory
buffer seemed to be independent of short-term memory processes.Comment: Human Movement Science (2011) epub ahead of prin
3D-2D ultrasound feature-based registration for navigated prostate biopsy: A feasibility study
International audienceThe aim of this paper is to describe a 3D-2D ultrasound feature-based registration method for navigated prostate biopsy and its first results obtained on patient data. A system combining a low-cost tracking system and a 3D-2D registration algorithm was designed. The proposed 3D-2D registration method combines geometric and image-based distances. After extracting features from ultrasound images, 3D and 2D features within a defined distance are matched using an intensity-based function. The results are encouraging and show acceptable errors with simulated transforms applied on ultrasound volumes from real patients
Computer-assisted access to the kidney
OBJECTIVES: The aim of this paper is to introduce the principles of
computer-assisted access to the kidney. The system provides the surgeon with a
pre-operative 3D planning on computed tomography (CT) images. After a rigid
registration with space-localized ultrasound (US) data, preoperative planning
can be transferred to the intra-operative conditions and an intuitive
man-machine interface allows the user to perform a puncture. MATERIAL AND
METHODS: Both CT and US images of informed normal volunteer were obtained to
perform calculation on the accuracy of registration and punctures were carried
out on a kidney phantom to measure the precision of the whole of the system.
RESULTS: We carried out millimetric registrations on real data and guidance
experiments on a kidney phantom showed encouraging results of 4.7 mm between
planned and reached targets. We noticed that the most significant error was
related to the needle deflection during the puncture. CONCLUSION: Preliminary
results are encouraging. Further work will be undertaken to improve efficiency
and accuracy, and to take breathing into account
Initial validation of a virtual-reality learning environment for prostate biopsies: realism matters!
: Introduction-objectives: A virtual-reality learning environment dedicated
to prostate biopsies was designed to overcome the limitations of current
classical teaching methods. The aim of this study was to validate reliability,
face, content and construct of the simulator. Materials and methods: The
simulator is composed of a) a laptop computer, b) a haptic device with a stylus
that mimics the ultrasound probe, c) a clinical case database including three
dimensional (3D) ultrasound volumes and patient data and d) a learning
environment with a set of progressive exercises including a randomized 12-core
biopsy procedure. Both visual (3D biopsy mapping) and numerical (score)
feedback are given to the user. The simulator evaluation was conducted in an
academic urology department on 7 experts and 14 novices who each performed a
virtual biopsy procedure and completed a face and content validity
questionnaire. Results: The overall realism of the biopsy procedure was rated
at a median of 9/10 by non-experts (7.1-9.8). Experts rated the usefulness of
the simulator for the initial training of urologists at 8.2/10 (7.9-8.3), but
reported the range of motion and force feedback as significantly less realistic
than novices (p=0.01 and 0.03 respectively). Pearson's r correlation
coefficient between correctly placed biopsies on the right and left side of the
prostate for each user was 0.79 (p<0.001). The 7 experts had a median score of
64% (59-73), and the 14 novices a median score of 52% (43-67), without reaching
statistical significance (p=0,19). Conclusion: The newly designed virtual
reality learning environment proved its versatility and its reliability, face
and content were validated. Demonstrating the construct validity will require
improvements to the realism and scoring system used
Segmentation, separation and pose estimation of prostate brachytherapy seeds in CT images.
International audienceIn this paper, we address the development of an automatic approach for the computation of pose information (position + orientation) of prostate brachytherapy loose seeds from 3D CT images. From an initial detection of a set of seed candidates in CT images using a threshold and connected component method, the orientation of each individual seed is estimated by using the principal components analysis (PCA) method. The main originality of this approach is the ability to classify the detected objects based on a priori intensity and volume information and to separate groups of closely spaced seeds using three competing clustering methods: the standard and a modified k-means method and a Gaussian mixture model with an Expectation-Maximization algorithm. Experiments were carried out on a series of CT images of two phantoms and patients. The fourteen patients correspond to a total of 1063 implanted seeds. Detections are compared to manual segmentation and to related work in terms of detection performance and calculation time. This automatic method has proved to be accurate and fast including the ability to separate groups of seeds in a reliable way and to determine the orientation of each seed. Such a method is mandatory to be able to compute precisely the real dose delivered to the patient post-operatively instead of assuming the alignment of seeds along the theoretical insertion direction of the brachytherapy needles
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