Diverse stereotactic neuro-navigation systems are used daily in neurosurgery and novel systems are continuously being developed. Prior to clinical implementation of new surgical tools, methods or instruments, in vitro experiments on phantoms should be conducted. A stereotactic neuro-navigation phantom denotes a rigid or deformable structure resembling the cranium with the intracranial area. The use of phantoms is essential for the testing of complete procedures and their workflows, as well as for the final validation of the application accuracy. The aim of this study is to provide a systematic review of stereotactic neuro-navigation phantom designs, to identify their most relevant features, and to identify methodologies for measuring the target point error, the entry point error, and the angular error (α). The literature on phantom designs used for evaluating the accuracy of stereotactic neuro-navigation systems, i.e., robotic navigation systems, stereotactic frames, frameless navigation systems, and aiming devices, was searched. Eligible articles among the articles written in English in the period 2000-2020 were identified through the electronic databases PubMed, IEEE, Web of Science, and Scopus. The majority of phantom designs presented in those articles provide a suitable methodology for measuring the target point error, while there is a lack of objective measurements of the entry point error and angular error. We identified the need for a universal phantom design, which would be compatible with most common imaging techniques (e.g., computed tomography and magnetic resonance imaging) and suitable for simultaneous measurement of the target point, entry point, and angular errors.

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This paper explores the possibility of tool wear classification in stone drilling. Wear model is based on Radial Basis Function Neural Network which links tool wear features extracted from motor drive current signals and acoustic emission signals with two wear levels – sharp and worn drill. Signals were measured during stone drilling under different cutting conditions, and then filtered before tool wear features extraction. Features were obtained from time and frequency domain. They have been analyzed individually and in combinations. The results indicate tool wear monitoring capacity of the proposed model in stone drilling, and its potential for simple and cost-effective integration with CNC machine tools.

In this paper we propose a novel phantom design for measuring application accuracy of neurosurgical robotic systems and stereotactic frames. We develop a novel phantom (T-Phantom) which enables simultaneous localization of translational displacements in entry and target points. The phantom consists of multiple trajectories positioned around a localizer feature simulating approach trajectories in neurosurgical procedures on the intracranial space. Each trajectory consists of two parallel and coaxial hollow cylinders printed in selective laser sintering technology. We apply a stereo vision measuring method for precise measurements of translational displacements in target and entry positions. The paper further provides a systematic comparison of phantom designs originating from stereotactic frames and neurosurgical robotic systems. To the author's knowledge, the developed T-Phantom is the first stereotactic phantom which enables simultaneous measurements both in deviation from target and entry positions and angular deviation from the planned trajectory.

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