3D-Printing of Arteriovenous Malformations for Radiosurgical Treatment: Pushing Anatomy Understanding to Real Boundaries

open9noRadiosurgery of arteriovenous malformations (AVMs) is a challenging procedure. Accuracy of target volume contouring is one major issue to achieve AVM obliteration while avoiding disastrous complications due to suboptimal treatment. We describe a technique to improve the understanding of the complex AVM angioarchitecture by 3D prototyping of individual lesions. Arteriovenous malformations of ten patients were prototyped by 3D printing using 3D rotational angiography (3DRA) as a template. A target volume was obtained using the 3DRA; a second volume was obtained, without awareness of the first volume, using 3DRA and the 3D-printed model. The two volumes were superimposed and the conjoint and disjoint volumes were measured. We also calculated the time needed to perform contouring and assessed the confidence of the surgeons in the definition of the target volumes using a six-point scale. The time required for the contouring of the target lesion was shorter when the surgeons used the 3D-printed model of the AVM (p=0.001). The average volume contoured without the 3D model was 5.6 ± 3 mL whereas it was 5.2 ± 2.9 mL with the 3D-printed model (p=0.003). The 3D prototypes proved to be spatially reliable. Surgeons were absolutely confident or very confident in all cases that the volume contoured using the 3D-printed model was plausible and corresponded to the real boundaries of the lesion. The total cost for each case was 50 euros whereas the cost of the 3D printer was 1600 euros. 3D prototyping of AVMs is a simple, affordable, and spatially reliable procedure that can be beneficial for radiosurgery treatment planning. According to our preliminary data, individual prototyping of the brain circulation provides an intuitive comprehension of the 3D anatomy of the lesion that can be rapidly and reliably translated into the target volume.openCONTI, Alfredo; PONTORIERO, ANTONIO; IATI', GIUSEPPE; MARINO, DANIELE; LA TORRE, Domenico; VINCI, Sergio Lucio; GERMANO', Antonino Francesco; PERGOLIZZI, Stefano; TOMASELLO, FrancescoCONTI, Alfredo; PONTORIERO, ANTONIO; IATI', GIUSEPPE; MARINO, DANIELE; LA TORRE, Domenico; VINCI, Sergio Lucio; GERMANO', Antonino Francesco; PERGOLIZZI, Stefano; TOMASELLO, Francesc

From Concept to Market: Surgical Robot Development

Surgical robotics and supporting technologies have really become a prime example of modern applied information technology infiltrating our everyday lives. The development of these systems spans across four decades, and only the last few years brought the market value and saw the rising customer base imagined already by the early developers. This chapter guides through the historical development of the most important systems, and provide references and lessons learnt for current engineers facing similar challenges. A special emphasis is put on system validation, assessment and clearance, as the most commonly cited barrier hindering the wider deployment of a system

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Control techniques for mechatronic assisted surgery

The treatment response for traumatic head injured patients can be improved by using an autonomous robotic system to perform basic, time-critical emergency neurosurgery, reducing costs and saving lives. In this thesis, a concept for a neurosurgical robotic system is proposed to perform three specific emergency neurosurgical procedures; they are the placement of an intracranial pressure monitor, external ventricular drainage, and the evacuation of chronic subdural haematoma. The control methods for this system are investigated following a curiosity led approach. Individual problems are interpreted in the widest sense and solutions posed that are general in nature. Three main contributions result from this approach: 1) a clinical evidence based review of surgical robotics and a methodology to assist in their evaluation, 2) a new controller for soft-grasping of objects, and 3) new propositions and theorems for chatter suppression sliding mode controllers. These contributions directly assist in the design of the control system of the neurosurgical robot and, more broadly, impact other areas outside the narrow con nes of the target application. A methodology for applied research in surgical robotics is proposed. The methodology sets out a hierarchy of criteria consisting of three tiers, with the most important being the bottom tier and the least being the top tier. It is argued that a robotic system must adhere to these criteria in order to achieve acceptability. Recent commercial systems are reviewed against these criteria, and are found to conform up to at least the bottom and intermediate tiers. However, the lack of conformity to the criteria in the top tier, combined with the inability to conclusively prove increased clinical benefit, particularly symptomatic benefit, is shown to be hampering the potential of surgical robotics in gaining wide establishment. A control scheme for soft-grasping objects is presented. Grasping a soft or fragile object requires the use of minimum contact force to prevent damage or deformation. Without precise knowledge of object parameters, real-time feedback control must be used to regulate the contact force and prevent slip. Moreover, the controller must be designed to have good performance characteristics to rapidly modulate the fingertip contact force in response to a slip event. A fuzzy sliding mode controller combined with a disturbance observer is proposed for contact force control and slip prevention. The robustness of the controller is evaluated through both simulation and experiment. The control scheme was found to be effective and robust to parameter uncertainty. When tested on a real system, however, chattering phenomena, well known to sliding mode research, was induced by the unmodelled suboptimal components of the system (filtering, backlash, and time delays). This reduced the controller performance. The problem of chattering and potential solutions are explored. Real systems using sliding mode controllers, such as the control scheme for soft-grasping, have a tendency to chatter at high frequencies. This is caused by the sliding mode controller interacting with un-modelled parasitic dynamics at the actuator-input and sensor-output of the plant. As a result, new chatter-suppression sliding mode controllers have been developed, which introduce new parameters into the system. However, the effect any particular choice of parameters has on system performance is unclear, and this can make tuning the parameters to meet a set of performance criteria di cult. In this thesis, common chatter-suppression sliding mode control strategies are surveyed and simple design and estimation methods are proposed. The estimation methods predict convergence, chattering amplitude, settling time, and maximum output bounds (overshoot) using harmonic linearizations and invariant ellipsoid sets

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Stereotactic radiosurgery for intracranial metastases from gastrointestinal malignancies: a retrospective analysis

INTRODUCTION: Cancers of the gastrointestinal tract are the second most prevalent malignancy with 289,610 new cases last year and the second most common cause of cancer-related death with 150,000 deaths last year in the United States. Prognosis for patients with these malignancies is poor and worsens significantly once the cancer has metastasized to the brain. We evaluated the outcome of patients following Stereotactic Radiosurgery (SRS) for brain metastases (BM) in individuals with GI cancers to identify safety and effectivity of treatment and we assessed prognostic factors that affect tumor control and survival. OBJECTIVES: By the conclusion of this session, participants should be able to: 1) Identify an effective treatment for brain metastases from GI cancers in terms of increasing survival; 2) Identify which treatment provides the best local and distant control of CNS disease; 3) Discuss the effects of different prognostic factors on local control and survival. METHODS: This is a retrospective analysis of 58 brain metastases from 18 consecutive patients who underwent SRS treatment at BIDMC between 2006 and 2013. 11/18 patients underwent prior microsurgical resection for their metastases and 3/18 patients had undergone Whole Brain Radiation Therapy (WBRT). Overall Survival (OS), Local Control (LC), Distal control (DC), and prognostic factors such as age, number of brain metastases (BM), Karnofsky Performance Status (KPS), Recursive Partition Analysis (RPA) and Disease Specific Graded Prognostic Assessment (Ds-GPA) class were evaluated. RESULTS: The median overall survival (mOS) for the entire cohort was 14 months after the diagnosis of BM. The mOS for patients receiving only SRS, Surgical Resection + SRS, and WBXRT + SRS were 8 months, 18 months, and 13 months respectively. The difference in overall survival between treatment groups was not found to be statistically significant. Increasing number of BM was a factor shown to negatively influence survival. Local control was achieved in 55% of lesions after SRS, and in 75% of lesions that were surgically resected followed by SRS boost to the resection cavity. The difference in local control between SRS alone vs. Surgery + SRS was found to be statistically significant (p = 0.013). CONCLUSION: With a higher overall survival and significantly better local control rates, Surgery followed by SRS boost to the resection cavity should be considered as the treatment of choice in this specific subgroup of cancer patients as this study shows that they benefit from this more aggressive treatment option