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Biomedical subjects

P Cinquin

Publications and source records attributed to P Cinquin.

At least 37 records · Page 2Linked to original sources
PubMed1995

Patient setup optimization for external conformal radiotherapy.

The aim of conformal radiotherapy is to deliver precisely a specific dose of radiation to a planning target volume, concurrently radiating as little healthy tissue and organs as possible. This can be accomplished only with the accurate positioning of the patient with respect to the radiotherapy system. In this paper, we describe a system to achieve a higher overall accuracy in the delivery of a prostatic radiation boost for treatment of carcinoma of the prostate. The system is based on the use of ultrasound images for measuring the actual position of the patient's prostate just before the radiation. Since these images are registered with pretreatment computed tomography or magnetic resonance imaging, the position and orientation of the planning target volume are computed with respect to the radiotherapy system and can be corrected as needed. This system is under clinical evaluation.

Computer Simulation↗
PubMed1995

Computer-assisted bronchoscopy: aims and research perspectives.

The introduction of spiral computed tomography (CT) of the thoracic cavity has allowed the development of new visualization tools. These tools provide a three-dimensional (3-D) endoluminal reconstruction of the tracheobronchial tree, as it would be viewed through a fibroscopic instrument. However, 3-D reconstruction techniques cannot replace conventional fibroscopy, which remains indispensable for obtaining histological samples. Furthermore, when CT-detected mediastinal or parenchymal lesions are not seen during fiberoptic bronchoscopy, guiding transbronchial needle biopsy is a major challenge. Computer-guided transbronchial biopsy involves the fusion of image data from both CT slices and bronchoscopic video sequences. This fusion is described in this paper in two parts. First, we present a segmentation process, using mathematical morphology operators, in order to analyze the video sequence and localize the bronchoscopic camera within the tracheobronchial tree. Second, we present tools used to match this localization knowledge with CT data. Finally, we produce images that create a bronchoscopic augmented reality, using elements extracted from the CT examination.

Biopsy, Needle↗
PubMed1995

Mathematical determination of the tibial insertion of the patellar tendon using computed tomography images.

Misalignment of the extensor apparatus is an essential factor in impairment of the patellar-femoral joint. This may be partly or entirely responsible for patellar dislocation or lateral patellar-femoral arthrosis. One surgical method to correct the pathology is medial transposition of the patellar ligament on the tibial tuberosity (anteriorly or posteriorly, distally or ventrally). These interventions correct misalignment of the extensor apparatus relative to statistical norms. We propose a mathematical method based on the use of computed tomography (CT) images to determine the ideal tibial insertion for the patellar tendon. This method is based on biomechanical modeling and the use of equipressure criteria. It is the first step in allowing the use of mathematics to model correctly tibial insertion of the patellar ligament, an entirely new development. This is important because it will allow surgeons greater accuracy in distal correction of extensor apparatus misalignments.

Biomechanical Phenomena↗
PubMed1995

Building a hybrid patient's model for augmented reality in surgery: a registration problem.

In the field of Augmented Reality in Surgery, building a hybrid patient's model, i.e. merging all the data and systems available for a given application, is a difficult but crucial technical problem. The purpose is to merge all the data that constitute the patient model with the reality of the surgery, i.e. the surgical tools and feedback devices. In this paper, we first develop this concept, we show that this construction comes to a problem of registration between various sensor data, and we detail a general framework of registration. The state of the art in this domain is presented. Finally, we show results that we have obtained using a method which is based on the use of anatomical reference surfaces. We show that in many clinical cases, registration is only possible through the use of internal patient structures.

Algorithms↗
PubMed1995

Computer generated visual assistance during retroperitoneoscopy.

In this paper we present a system of computer assisted surgery, the function of which is to enhance the real time feedback between the patient's body, the surgical tools and the surgeon. We show using such a system during some surgical operations--in our case, retroperitoneoscopy. After giving the requirements for such a system, we describe the components currently used in our experiments. We detail the different problems and our current solutions; photographs of an experiment carried out on a cadaver and of classical operations are shown in this paper.

Computer Simulation↗
PubMed1995

Interpretation of multimodal medical images using connectionist and variational methods.

Our medical objective is to match multimodal 3D medical images into a coherent model of the patient, from which diagnosis can be assessed and therapeutics guided. 3D image segmentation is absolutely necessary to reach this objective. We investigate two complementary approaches for segmenting 3D medical images. First we present some definitions, basic properties and recent theoretical results about formal neural networks, and show that these results can be applied to brain tumour segmentation. A variational approach (called the 'snake spline' method) is then detailed. We finally show how segmented 3D images can be used for multimodal image matching.

Algorithms↗
PubMed1995

[Image information systems].

The notion of image information system (IIS) is introducted, based on an on-going experience in Grenoble's university hospital. The objectives and of a IIS are clarified, and the basic principles of its architecture are presented.

Computer Communication Networks↗
PubMed1995

[Place of computer-assisted surgery in the evaluation of lymphatics metastases in pelvic cancers. Exploration by retroperitoneoscopy].

Extraperitoneal pelvioscopy is a surgical endoscopy without insufflation which enables exploration of the extraperitoneal space in order to obtain biopsy specimens of adenopathies and tumors. 189 extraperitoneal endoscopy have been performed since 1976. When made through an iliac approach, the Extraperitoneal Endoscopy explores iliac and pelvic lymph nodes. It is an indication when checking the extension of uterine, prostatic and bladder cancers. Recently, a system of computerized assistance has been added to the initial method. Its aim is to guide the movements of the surgical tool when the indication is difficult: overweight patient, small tumors, risky tumoral environment. The basic principle is to show recalculated RMI or CT scan sections of the patient during the intervention, on which appear in real time the positions of the endoscope and that of the target to biopsy. The authors describe the technical ways of the method, the system of tridimensional localisation included in the operating room and the sort of interface given to the surgeon. In the future, the realisation of a simulator of intervention will allow diffusion and teaching of this intervention.

Equipment Design↗
PubMed1993

Conformal external radiotherapy of prostatic carcinoma: requirements and experimental results.

The aim of conformal radiotherapy is to deliver, with high precision, a specific dose (which may be a high dose) to a planning target volume, concurrently with irradiating as little as possible healthy tissue and organs at risk. Radiation therapy may suffer from a number of problems that result in both over- or under-sizing the irradiation fields, making over-rough simplifications of the irradiation ballistics and delivering an insufficient tumoral dose (to spare critical organs and reduce toxicity). One of these problems lies in the accurate positioning of the planning target volume with respect to the irradiation system, thence in the correct execution of the ballistics. In this paper, we describe a system aiming at achieving a higher overall accuracy in the delivery of prostatic boost for carcinoma of the prostate. The system is based on the use of ultrasonic images for measuring the actual position of the prostate just before irradiation. Since these images are registered with pre-operative (CT or MR) images, the position and orientation of the planning target volume is computed with respect to the irradiation system, and can be corrected accordingly. First experiments have been performed on dummies, and the results are discussed.

Humans↗
PubMed1993

Pre- and intra-irradiation multimodal image registration: principles and first experiments.

Accurately repositioning the patient with respect to CT or MR images is essential for high precision radiotherapy. We show that portal images may be automatically registered with 3D pre-session data (typically morphological images like CT or MR images), thus enabling an automatic adjustment of the planned strategy to the actual position of the patient. Based on computer vision techniques, the principles of this new method of multimodal image registration are presented, and the first experiments with a phantom are analysed.

Humans↗
PubMed1993

[Computer-assisted medicosurgical gestures].

Computer assisted medical interventions (CAMI) aim at minimizing the invasive part of some medical or surgical techniques. This general objective is discussed, together with its scientific consequences. The general methodology of CAMI is then laid out, with special emphasis on its three fundamental steps: perception-reasoning-action. Each of these steps is illustrated with feasibility demonstrations in various domains. We then conclude by analysing the part this sort of technique could play in an hospital, together with the colaborations such a project implies.

Diagnosis, Computer-Assisted↗
PubMed1992

Potential use of robots in endoscopic neurosurgery.

A 6-axis stereotactic robot has been designed and linked to a stereotactic frame for routine use. Robot software allows the positioning of a probe holder in order to reach a given target. A calibration step enables the robot to compute the position of the x-ray beam and correct its final position to avoid parallax errors. The co-ordinates of the target are presently taken from anteroposterior and lateral X-rays using a digitizing table. Connection with a digitized angiography system is in progress and will allow direct sampling of numerical data from the x-ray data. Further steps will include connections with a 3D-reconstructed image from MRI and CAT as well as with a resident computerized atlas. Present experience after 14 months of daily practice represents 140 stereotactic procedures which can be extended to any special use, including endoscopic approaches.

Brain Diseases↗
PubMed1990

[Three-dimensional imaging of the carpus].

Since 1987, the authors have developed three-dimensional (3D) imaging of carpus. This reconstruction based on 30 CT scans of the carpus is a new approach to imaging and allows spatial visualisation of the complex shapes of the carpal skeleton from all angles and views. The development of this technique should lead to a better understanding of the intimate physiology of the carpus and should allow the development of a real simulator of the wrist for precise planning of surgical procedures (osteotomy, intracarpal arthrodeses, etc.). It also helps to elucidate complex pathological images which are not always easy to interpret on CT scans.

Carpal Bones↗