90 research outputs found

    Interactive Planning of Cryotherapy Using Physically-Based Simulation

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    International audienceCryotherapy is a rapidly growing minimally invasive technique for the treatment of certain tumors. It consists in destroying cancer cells by extreme cold delivered at the tip of a needle-like probe. As the resulting iceball is often smaller than the targeted tumor, a key to the success of cryotherapy is the planning of the position and orientation of the multiple probes required to treat a tumor, while avoiding any damage to the surrounding tissues. In order to provide such a planning tool, a number of challenges need to be addressed such as fast and accurate computation of the freezing process or interactive positioning of the virtual cryoprobes in the pre-operative image volume. To address these challenges, we present an approach which relies on an advanced computational framework, and a gesture-based planning system using contact-less technology to remain compatible with a use in a sterile environment

    GPU-based 3D iceball modeling for fast cryoablation simulation and planning

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    Purpose The elimination of abdominal tumors by percutaneous cryoablation has been shown to be an effective and less invasive alternative to open surgery. Cryoablation destroys malignant cells by freezing them with one or more cryoprobes inserted into the tumor through the skin. Alternating cycles of freezing and thawing produce an enveloping iceball that causes the tumor necrosis. Planning such a procedure is difficult and time-consuming, as it is necessary to plan the number and cryoprobe locations and predict the iceball shape which is also influenced by the presence of heating sources, e.g., major blood vessels and warm saline solution, injected to protect surrounding structures from the cold. Methods This paper describes a method for fast GPU-based iceball modeling based on the simulation of thermal propagation in the tissue. Our algorithm solves the heat equation within a cube around the cryoprobes tips and accounts for the presence of heating sources around the iceball. Results Experimental results of two studies have been obtained: an ex vivo warm gel setup and simulation on five retrospective patient cases of kidney tumors cryoablation with various levels of complexity of the vascular structure and warm saline solution around the tumor tissue. The experiments have been conducted in various conditions of cube size and algorithm implementations. Results show that it is possible to obtain an accurate result within seconds. Conclusion The promising results indicate that our method yields accurate iceball shape predictions in a short time and is suitable for surgical planning

    Surgery Training, Planning and Guidance Using the SOFA Framework

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    International audienceIn recent years, an active development of novel technologies dealing with medical training, planning and guidance has become an increasingly important area of interest in both research and health-care manufacturing. A combination of advanced physical models, realistic human-computer interaction and growing computational power is bringing new solutions in order to help both medical students and experts to achieve a higher degree of accuracy and reliability in surgical interventions. In this paper, we present three different examples of medical physically-based simulations implemented in a common software platform called SOFA. Each example represents a different application: training for cardiac electrophysiology, pre-operative planning of cryosurgery and per-operative guidance for laparoscopy. The goal of this presentation is to evaluate the realism, accuracy and efficiency of the simulations, as well as to demonstrate the potential and flexibility of the SOFA platform

    Renal Tumor Cryoablation Planning. The Efficiency of Simulation on Reconstructed 3D CT Scan

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    Introduction & Objective: Nephron-sparing surgical techniques risks are related to tumor relationships with adjacent anatomic structures. Complexity of the renal anatomy drives the interest to develop tools for 3D reconstruction and surgery simulation. The aim of the article was to assess the simulation on reconstructed 3D CT scan used for planning the cryoablation. Material & Method: A prospective randomized study was performed between Jan. 2007 and July 2009 on 27 patients who underwent retroperitoneoscopic T1a renal tumors cryoablation (RC). All patients were assessed preoperatively by CT scan, also used for 3D volume rendering. In the Gr.A, the patients underwent surgery planning by simulation on 3D CT scan. In the Gr.B., patients underwent standard RC. The two groups were compared in terms of surgical time, bleeding, postoperative drainage, analgesics requirement, hospital stay, time to socio-professional reintegration. Results: Fourteen patients underwent preoperative cryoablation planning (Gr.A) and 13 patients underwent standard CR (Gr.B). All parameters analyzed were shorter in the Gr.A. On multivariate logistic regression, only shortens of the surgical time (138.79±5.51 min. in Gr.A. vs. 140.92±5.54 min in Gr.B.) and bleeding (164.29±60.22 mL in Gr.A. vs. 215.38±100.80 mL in Gr.B.) achieved statistical significance (p<0.05). The number of cryoneedles assessed by simulation had a 92.52% accuracy when compared with those effectively used. Conclusions: Simulation of the cryoablation using reconstructed 3D CT scan improves the surgical results. The application used for simulation was able to accurately assess the number of cryoneedles required for tumor ablation, their direction and approach

    Thermostability of Biological Systems: Fundamentals, Challenges, and Quantification

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    This review examines the fundamentals and challenges in engineering/understanding the thermostability of biological systems over a wide temperature range (from the cryogenic to hyperthermic regimen). Applications of the bio-thermostability engineering to either destroy unwanted or stabilize useful biologicals for the treatment of diseases in modern medicine are first introduced. Studies on the biological responses to cryogenic and hyperthermic temperatures for the various applications are reviewed to understand the mechanism of thermal (both cryo and hyperthermic) injury and its quantification at the molecular, cellular and tissue/organ levels. Methods for quantifying the thermophysical processes of the various applications are then summarized accounting for the effect of blood perfusion, metabolism, water transport across cell plasma membrane, and phase transition (both equilibrium and non-equilibrium such as ice formation and glass transition) of water. The review concludes with a summary of the status quo and future perspectives in engineering the thermostability of biological systems

    Simulasi Bioheat Transfer Untuk Perencanaan Cryosurgery Pada Kanker Paru-paru

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    ABSTRAK Pada Tugas Akhir ini akan membahas simulasi pemusnahan sel kanker yang terjadi pada organ paru-paru menggunakan proses cryosurgery. Pemusnahan dilakukan dengan cara mengalirkan cairan nitrogen kemudian akan menyebarkan suhu yang sangat dingin. Distribusi suhu dilakukan dengan menggunakan pengembangan skema numerik Godunov dan metode volume hingga. Persamaan temperatur yang digunakan mengaplikasikan perubahan fase yang melibatkan batas bergerak. Persamaan numerik divalidasi dengan solusi eksak, sehingga memberikan hasil yang akurat dan dapat digunakan pada sistem dua dimensi. Pada analisa ini akan lebih detail pada pengembangan simulasi numerik satu dimensi dan dua dimensi untuk simulasi perpindahan panas. Hasil simulasi berupa gambar yang memberikan infomasi profil temperatur dan posisi interface, sehingga dapat terlihat jelas bagaimana proses cryosurgery dapat terjadi. Dengan simulasi ini diharapkan dapat menentukan waktu optimal dari proses cryosurgery itu sendiri, sehingga dapat mengetahui waktu yang dibutuhkan sedemikian hingga memaksimalkan jaringan kanker dan meminimalkan jaringan sehat disekitar akibat dari proses cryosurgery. Sehingga dengan melihat hasil simulasi, dokter dapat meminimalisasi resiko yang diakibatkan pada proses yang berjalan secara nyata. Kata Kunci : cryosurgery, perpindahan panas, metode godunov, metode volume hingga

    Effective treatment of solid tumors via Cryosurgery

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    Ph.DDOCTOR OF PHILOSOPH

    Применение метода конечных элементов в процессе математического моделирования в урологии

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    The article presents data on possibility of the application of the method of finite elements (FEM) in the mathematical modeling of various diseases of the organs of the urogenital system, their diagnostics and treatment. Special attention was paid to the prospects of application of FEM for modelling methods of surgical treatment of diseases of the kidneys and urinary tract.В статье представлены данные о возможностях применения метода конечных элементов (МКЭ) в математическом моделировании различных заболеваний органов мочеполовой системы, их диагностики и лечения. Особое внимание уделено перспективам применения МКЭ для моделирования методов оперативного лечения заболеваний почек и мочевыводящих путей

    Could the heat sink effect of blood flow inside large vessels protect the vessel wall from thermal damage during RF-assisted surgical resection?

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    Purpose: To assess by means of computer simulations whether the heat sink effect inside a large vessel (portal vein) could protect the vessel wall from thermal damage close to an internally cooled electrode during radiofrequency (RF)-assisted resection. Methods: First, in vivo experiments were conducted to validate the computational model by comparing the experimental and computational thermal lesion shapes created around the vessels. Computer simulations were then carried out to study the effect of different factors such as device-tissue contact, vessel position, and vessel-device distance on temperature distributions and thermal lesion shapes near a large vessel, specifically the portal vein. Results: The geometries of thermal lesions around the vessels in thein vivo experiments were in agreement with the computer results. The thermal lesion shape created around the portal vein was significantly modified by the heat sink effect in all the cases considered. Thermal damage to the portal vein wall was inversely related to the vessel-device distance. It was also more pronounced when the device-tissue contact surface was reduced or when the vessel was parallel to the device or perpendicular to its distal end (blade zone), the vessel wall being damaged at distances less than 4.25 mm. Conclusions: The computational findings suggest that the heat sink effect could protect the portal vein wall for distances equal to or greater than 5 mm, regardless of its position and distance with respect to the RF-based device. © 2014 American Association of Physicists in Medicine.This work received financial support from the Spanish "Plan Nacional de I+D+I del Ministerio de Ciencia e Innovacion" Grant No. TEC2011-27133-C02-01 and -02, also from the Universitat Politecnica de Valencia (INNOVA11-01-5502; and PAID-06-11 Ref. 1988). A. Gonzalez-Suarez is the recipient of a Grant VALi+d (ACIF/2011/194) from the Generalitat Valenciana. 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