RESUMO
BACKGROUND: One of the main sources of error in commercial surgical navigation systems is the tracking of surgical tools. Mainstream systems typically use optical or electromagnetic tracking technologies, which exhibit accuracies of the order of 1 mm. The objective of this study was to introduce a lightweight high-precision passive coordinate measurement arm into an augmented reality-based surgical navigation system to track a rigid endoscope. METHODS: A series of dry laboratory experiments were run to compare the tracking performance of an optical tracking device, a passive coordinate measurement arm and a hybrid set-up. RESULTS: The optical device displayed overlay errors in the range 1.5-3 mm. For the precision measurement arm, 96% of overlay errors were < 1 mm. The hybrid set-up exhibited overlay errors in the range 0.8-1.5 mm. CONCLUSIONS: The reported experiments showed that a high-precision articulated measurement arm could be used as a motion-tracking device for surgical instruments in augmented-reality surgical navigation.
Assuntos
Endoscópios , Endoscopia/métodos , Cirurgia Assistida por Computador/métodos , Algoritmos , Radiação Eletromagnética , Endoscopia/instrumentação , Desenho de Equipamento , Humanos , Imageamento Tridimensional/instrumentação , Movimento (Física) , Óptica e Fotônica , Reprodutibilidade dos Testes , Robótica , Cirurgia Assistida por Computador/instrumentaçãoRESUMO
A finite-element (FE) model of human skin is proposed for future use in an interactive real-time surgical simulation to teach surgeons procedures, such as facial reconstruction using skin-flap repair. For this procedure, skin is cut into flaps that are stretched to cover openings in the face. Thus, the model must recreate the visual, haptic, and force feedback expected by the surgeon. To develop the FE model, a series of in vitro experiments were conducted on samples of human skin, subjected to uniaxial and planar tensile straining. Reduced polynomial hyperelastic (HE) materials were found to fit many of the samples' stress-strain data well. Finally, an explicit dynamic FE mesh was developed based on the fitted HE material models. A total Lagrangian formulation with the half-step central difference method was employed to integrate the dynamic equation of motion of the mesh. The mesh was integrated into two versions of a real-time skin simulator: a single-threaded version running on a computer's main central processing unit and a multithreaded version running on the computer's graphics card. The latter was achieved by exploiting recent advances in programmable graphics technology.
Assuntos
Procedimentos Cirúrgicos Dermatológicos , Modelos Biológicos , Fenômenos Fisiológicos da Pele , Cirurgia Assistida por Computador/métodos , Interface Usuário-Computador , Simulação por Computador , Sistemas Computacionais , Módulo de Elasticidade/fisiologia , Análise de Elementos Finitos , Humanos , Estresse MecânicoRESUMO
In-vitro uniaxial stress tests were conducted on samples of healthy human skin, obtained as a result of plastic surgical procedures. Pairs of test strips were cut from each sample to assess the effects of local orthotropy. Each strip was then subjected to constant strain-rate tensile testing, to observe its stress/strain behaviour. Typical maximal values for Young's modulus were found to be approximately 15.3MPa and 3.48Mpa for Langer-aligned and perpendicular test strips, respectively.
Assuntos
Cirurgia Geral/educação , Pele , Simulação por Computador , Humanos , Técnicas In Vitro , Estresse Mecânico , Reino UnidoRESUMO
Existing simulation software, originally developed for the simulation and planning of inguinal hernia repair, was fused with two haptic feedback devices: the SensAble Technologies Phantom Desktop, and the ACROE/ICA Telluris system. The former allows easy integration on a PC-based platform, though in the long run, the Telluris system is preferred because of its robustness and its ability to design custom-built solutions.
