Publications

2011
X. Chen, K. Tuncali, A. H. Slocum, and C. J. Walsh, “Design of an instrument guide for MRI-guided percutaneous interventions,” in ASME Design of Medical Devices Conference, Minneapolis, Minnesota, USA, 2011. PDF
C. J. Walsh, A. H. Slocum, and R. Gupta, “Preliminary Evaluation of Robotic Needle Distal Tip Repositioning,” in Proc. SPIE 7901, Energy-based Treatment of Tissue and Assessment VI, 2011, pp. 790108. Publisher's VersionAbstract

Advances in medical imaging now provide detailed images of solid tumors inside the body and miniaturized energy delivery systems enable tumor destruction through local heating powered by a thin electrode. We have developed a robot for accurately repositioning the distal tip of a medical instrument such an ablation probe to adjacent points within tissue. The position accuracy in ballistics gelatin was evaluated in a 2D experimental setup with a digital SLR camera that was fixed to a rig that also contained the gelatin. The robot was mounted to the rig in such a way that the stylet was deployed in a plane parallel the camera's lens. A grid paper attached to the back of the box containing the gelatin provided a stationary reference point for each of the pictures taken and also served as a coordinate system for making measurements. The measurement repeatability error was found by taking a stylet tip position measurement five times for two different pictures and found to be 0.26 mm. For a stylet with a radius of curvature of 31.5 mm and a diameter of 0.838 mm, the targeting accuracy was found to be 2.5 ± 1.4 mm at points that were approximately 38 mm lateral from the cannula axis.

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C. J. Walsh, et al., “Smaller and Deeper Lesions Increase the Number of Acquired Scan Series in CT-guided Lung Biopsy,” Journal of Thoracic Imaging, vol. 26, no. 3, pp. 196-203, 2011. PDF
2010
C. J. Walsh, J. M. N. Martin, K. G. Vosburgh, N. C. Hanumara, A. H. Slocum, and R. Gupta, “Electromagnetic Guidance of a Patient-mounted Telerobot,” in Computer Assisted Radiology and Surgery, 2010. PDF
C. J. Walsh, J. C. Franklin, A. H. Slocum, and R. Gupta, “Characterization of Pre-curved Needles for use in Distal Tip Manipulation Mechanisms,” in Proceedings of the 2010 Design of Medical Devices Conference, Minneapolis, MN, USA, 2010. PDF
G. Rothenhofer, C. J. Walsh, and A. H. Slocum, “Transmission Ratio Based Analysis and Robust Design of Mechanisms,” Precision Engineering, vol. 34, no. 4, pp. 790-797, 2010. Publisher's VersionAbstract

This paper proposes an analytical approach to the robust design of mechanisms, to achieve motion and accuracy requirements given a desired transmission ratio and allowable geometrical variations. The focus is on four-bar and slider-crank mechanisms, which are common elements for the transmission of rotary motion, especially over distances, which are too big for the use of conventional elements such as gears, and motion along a predefined guide-curve, which often is a straight line. For many power transmission applications, a constant relation between the motions of an input and corresponding output element is required. For a four-bar linkage, a value of 1 is the only possible constant transmission ratio—achieved when the mechanism has a parallelogram configuration. In the case of a slider-crank linkage a constant transmission ratio can be achieved with a properly designed circular guide-curve, which makes the slider-crank essentially equivalent to a four-bar. In practice, however, as a result of variations in link lengths due to manufacturing tolerances and load-induced or thermal deformations, the transmission ratio for a parallelogram four-bar linkage will deviate substantially from its ideal theoretical value of 1. Even small changes in link lengths due to deformations or joint backlash can cause unacceptable instantaneous transmission ratio variations. The concepts presented are not limited to the design of four-bars and slider-cranks but can also be applied universally in the design of other mechanisms.

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C. J. Walsh, et al., “Women with Anorexia Nervosa: Finite Element and Trabecular Structure Analysis by Using Flat-Panel Volume CT,” Radiology, vol. 257, no. 1, pp. 167-174, 2010. PDF
2009
A. Seitel, et al., “Development and Evaluation of a New Image-Based User Interface for Robot-Assisted Needle Placements with the Robopsy System,” in Proc. SPIE, Lake Buena Vista, FL, 2009, vol. 7261, pp. 72610X-72610X-9. Publisher's VersionAbstract

The main challenges of Computed Tomography (CT)-guided organ puncture are the mental registration of the medical imaging data with the patient anatomy, required when planning a trajectory, and the subsequent precise insertion of a needle along it. An interventional telerobotic system, such as Robopsy, enables precise needle insertion, however, in order to minimize procedure time and number of CT scans, this system should be driven by an interface that is directly integrated with the medical imaging data. In this study we have developed and evaluated such an interface that provides the user with a point-and-click functionality for specifying the desired trajectory, segmenting the needle and automatically calculating the insertion parameters (angles and depth). In order to highlight the advantages of such an interface, we compared robotic-assisted targeting using the old interface (non-image-based) where the path planning was performed on the CT console and transferred manually to the interface with the targeting procedure using the new interface (image-based). We found that the mean procedure time (n=5) was 22±5 min (non-image-based) and 19±1 min (image-based) with a mean number of CT scans of 6±1 (non-image-based) and 5±1 (image-based). Although the targeting experiments were performed in gelatin with homogenous properties our results indicate that an image-based interface can reduce procedure time as well as number of CT scans for percutaneous needle biopsies.

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L. Maier-Hein, et al., “Human vs. Robot Operator Error in a Needle-Based Navigation System for Percutaneous Liver Interventions,” in Proc. SPIE, Lake Buena Vista, FL, 2009, vol. 7261, pp. 72610Y-72610Y-12. Publisher's VersionAbstract

Computed tomography (CT) guided percutaneous punctures of the liver for cancer diagnosis and therapy (e.g. tumor biopsy, radiofrequency ablation) are well-established procedures in clinical routine. One of the main challenges related to these interventions is the accurate placement of the needle within the lesion. Several navigation concepts have been introduced to compensate for organ shift and deformation in real-time, yet, the operator error remains an important factor influencing the overall accuracy of the developed systems. The aim of this study was to investigate whether the operator error and, thus, the overall insertion error of an existing navigation system could be further reduced by replacing the user with the medical robot Robopsy. For this purpose, we performed navigated needle insertions in a static abdominal phantom as well as in a respiratory liver motion simulator and compared the human operator error with the targeting error performed by the robot. According to the results, the Robopsy driven needle insertion system is able to more accurately align the needle and insert it along its axis compared to a human operator. Integration of the robot into the current navigation system could thus improve targeting accuracy in clinical use.

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V. Patil, S. J. R. Estépar, undefined, and K. Vosburgh, “Dynamic CT Scanner Environment Effects on a DC Electromagnetic Tracking System,” International Journal of Computer Assisted Radiology & Surgery, vol. 4, no. Suppl 1, pp. S339-S340, 2009. PDF
2008
C. J. Walsh, J. T. Heaton, J. B. Kobler, T. L. Szabo, and S. M. Zeitels, “Imaging of the Calf Vocal Fold with High Frequency Ultrasound,” The Laryngoscope, vol. 118, no. Oct., pp. 1894-1899, 2008. PDF
C. J. Walsh and C. K. Kearney, “Engineering, Science and Medicine: Transforming Healthcare,” Royal College of Surgeons in Ireland Student Medical Journal, vol. 1, no. 1, pp. 56-59, 2008. PDF
C. J. Walsh, N. C. Hanumara, A. H. Slocum, J. - A. Shepard, and R. Gupta, “A Patient-Mounted, Telerobotic Tool for CT-Guided Percutaneous Interventions,” ASME Journal of Medical Devices, vol. 2, no. 1, 2008. PDF
2007
C. J. Walsh, K. Endo, and H. Herr, “Quasi-Passive Leg Exoskeleton for Load Carrying Augmentation,” International Journal of Humanoid Robotics, Special Issue: Active Exoskeletons, vol. 4, no. 3, pp. 487-506, 2007.Abstract

A quasi-passive leg exoskeleton is presented for load-carrying augmentation during walking. The exoskeleton has no actuators, only ankle and hip springs and a knee variable damper. Without a payload, the exoskeleton weighs 11.7kg and requires only 2 Watts of electrical power during loaded walking. For a 36kg payload, we demonstrate that the quasi-passive exoskeleton transfers on average 80% of the load to the ground during the single support phase of walking. By measuring the rate of oxygen consumption on a study participant walking at a self-selected speed, we find that the exoskeleton slightly increases the walking metabolic cost of transport (COT) as compared to a standard loaded backpack (10% increase). However, a similar exoskeleton without joint springs or damping control (zero-impedance exoskeleton) is found to increase COT by 23% compared to the loaded backpack, highlighting the benefits of passive and quasi-passive joint mechanisms in the design of efficient, low-mass leg exoskeletons.

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C. J. Walsh, N. C. Hanumara, R. Gupta, J. - A. Shepard, and A. H. Slocum, “Evaluation of a Patient-Mounted, Remote Needle Guidance and Insertion System for CT-Guided, Percutaneous Lung Biopsies,” in Proceedings of the 2nd Frontiers in Biomedical Devices Conference, Irvine, California, 2007. PDF
N. C. Hanumara, C. J. Walsh, R. Gupta, J. - A. Shepard, and A. H. Slocum, “Human Factors Design for Intuitive Operation of a Low-cost, Image-Guided, Tele-Robotic Biopsy Assistant,” in Proceedings of the IEEE Engineering in Medicine and Biology Conference, Lyon, France, 2007, pp. 1257-1260. PDF
M. P. Ottensmeyer, M. Yip, C. J. Walsh, J. B. Kobler, J. T. Heaton, and S. M. Zeitels, “Intra-operative Laryngoscopic Instrument for Characterizing Vocal Fold Visco-elasticity,” in Proceedings of the 2nd Frontiers in Biomedical Devices Conference, Irvine, California, 2007. PDF
2006
C. J. Walsh, K. Pasch, and H. Herr, “An Autonomous, Underactuated Exoskeleton for Load Carrying Augmentation,” in Proc. Inter. Conf. on IROS, Beijing, China, 2006, pp. 1410-1415. PDF
C. J. Walsh, D. Paluska, K. Pasch, W. Grand, A. Valiente, and H. Herr, “Development of a Lightweight, Under-actuated Exoskeleton to Assist in Load Carrying in Walking,” in Proceedings of the IEEE International Conference on Robotics and Automation, Orlando, Florida, 2006, pp. 3485-3491. PDF
2005
S. R. H. Barrett, R. Gupta, N. C. Hanumara, A. H. Slocum, and C. J. Walsh, “Remote Needle Guidance System for Percutaneous Image Guided Biopsies,” in Proc. American Society of Mechanical Engineers International Design Engineering and Technical Conferences, Long Beach, California, 2005. PDF

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