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Electromagnetic (EM) tracking allows real-time in-body position measurements and is becoming the standard of clinical care. For examplein the interventional X-ray setting, EM tracked devices have becomea clinical standard within the context of electrophysiology ablation, and show great promise for advanced interventional radiology (IR)procedures. However, EM tracking systems are very sensitive to fielddistortions. In particular, the C-arm gantry in the interventionalX-ray (iXR) suite seems to significantly compromise the tracking capabilities. An EM field generator design that allows seamless integration with the interventional X-ray setup has hence become a market need. In this work, we design a new Philips Window Field Generator (PWFG) for use in the iXR suite. The design allows for non-obstructedimaging, while providing accurate tracking performance. Additionally, a prototype was designed evaluated for correcting the EM field distortions.

Aim: In the past decade ultrasound (US) has become the primary modality for interventional procedures, owing to its low cost, ease of use and real-time soft tissue visualization. The main limitation however, is the visualization of surgical tools due to their artifact prone response. Methods: This paper presents a new method for accurate,robust, inexpensive and real-time 3D tracking of surgical tools. The paper proposes a new sensing technology that utilizes miniature UScrystals that can be easily mounted on a surgical tool. As part ofcurrent clinical workflow, the US imager emits US waves to image thetissue. The sensor then converts this acoustic energy into electrical signals, which the system analyzes to reconstruct the 3D coordinates of the sensor. These coordinates can be used for 3D surgical navigation, similar to current day EM/optical tracking systems. Results: A prototype system with real-time 3D tool tracking and image enhancement was implemented. Extensive phantom experiments with 2mm single-element PZT crystal show robust tracking with a wide range of imaging conditions. The 3D tracking accuracy, tested using a precision robotic stage, was found to be 0.36 ± 0.16 mm in translation throughout the imaging volume. The experiments also show strong robustness to variations in tool position and orientation. Phantom experiments also prove ability to track a tool inside the beating heart. Conclusions: The paper proposes a new tool tracking technology for US-guidedinterventions, with a performance significantly superior to existing tool tracking technologies.

The famous max-flow min-cut theorem states that a source node can send information through a network ( ) to a sink node at a rate determined by the min-cut separating and . Recently, it has been shown that this rate can also be achieved for multicasting to several sinks provided that the intermediate nodes are allowed to re-encode the information they receive. We demonstrate examples of networks where theachievable rates obtained by coding at intermediate nodes are arbitrarily larger than if coding is not allowed. We give deterministic polynomial time algorithms and even faster randomized algorithms fordesigning linear codes for directed acyclic graphs with edges of unit capacity. We extend these algorithms to integer capacities and tocodes that are tolerant to edge failures.