Search

Motion estimation is an important issue in radiation therapy of moving organs. In particular, motion estimates from 4-D imaging can be used to compute the distribution of an absorbed dose during the therapeutic irradiation. We propose a strategy and criteria incorporating spatiotemporal information to evaluate the accuracy of model-based methods capturing breathing motion from 4-D CT images. This evaluation relies on the identification and tracking of landmarks on the 4-D CT images by medical experts. Three different experts selected more than 500 landmarks within 4-D CT images of lungs for three patients. Landmark tracking was performed at four instants of the expiration phase. Two metrics are proposed to evaluate the tracking performance of motion-estimation models. The first metric cumulates over the four instants the errors on landmark location. The second metric integrates the error over a time interval according to an a priori breathing model for the landmark spatiotemporal trajectory. This latter metric better takes into account the dynamics of the motion. A second aim of this paper is to estimate the impact of considering several phases of the respiratory cycle as compared to using only the extreme phases (end-inspiration and end-expiration). The accuracy of three motion estimation models (two image registration-based methods and a biomechanical method) is compared through the proposed metrics and statistical tools. This paper points out the interest of taking into account more frames for reliably tracking the respiratory motion. Index Terms--Deformable registration, radiotherapy, thorax, validation.

Whilst laparoscopic surgical simulators are becoming increasingly realistic they can not, as yet, fully replicate the experience of live surgery. In particular tissue dissection in one task that is particularly challenging to replicate. Limitation of current attempts to simulate tissue dissection include: poor visual rendering; over simplification of the task and; unrealistic tissue properties. In an effort to generate a more realistic model of tissue dissection in laparoscopic surgery we propose a novel method based on task analysis. Initially we have chosen to model only the basic geometrics of this task rather than a whole laparoscopic procedure. Preliminary work has led to the development of a real time simulator performing organ dissection with a haptic thread at 1000Hz. A virtual cutting tool, manipulated through a haptic device, in combination with 1D and 2D soft-tissue models accurately replicate the process of laparoscopic tissue dissection. [ABSTRACT FROM AUTHOR]

Inguinal hernia repair procedures are often one of the first surgical procedures faced by junior surgeons. The biggest challenge in this procedure for novice trainees is understanding the 3D spatial relations of the complex anatomy of the inguinal region, which is crucial for the effective and careful handling of the present anatomical structures in order to perform a successful and lasting repair. Such relationships are difficult to illustrate and comprehend through standard learning material. This paper presents our work in progress to develop a simulation-based teaching tool allowing junior surgeons to train the Lichtenstein tension-free open inguinal hernia repair technique for direct and indirect hernias, as well as to enforce their understanding of the spatial relations of the involved anatomy. [ABSTRACT FROM AUTHOR]

Inguinal hernia repair procedures are often one of the first surgical procedures faced by junior surgeons. The biggest challenge in this procedure for novice trainees is understanding the 3D spatial relations of the complex anatomy of the inguinal region, which is crucial for the effective and careful handling of the present anatomical structures in order to perform a successful and lasting repair. Such relationships are difficult to illustrate and comprehend through standard learning material. This paper presents our work in progress to develop a simulation-based teaching tool allowing junior surgeons to train the Lichtenstein tension-free open inguinal hernia repair technique for direct and indirect hernias, as well as to enforce their understanding of the spatial relations of the involved anatomy.