Abstract Thousands of medical researchers around the world use VTK —the Visualization Toolkit— an open-source, freely available software development toolkit providing advanced 3D interactive visualization, image processing and data analysis algorithms. They either use VTK directly in their in-house research applications or indirectly via one of the multitude of medical image analysis and bioinformatics applications that is built using VTK: Osirix, 3D Slicer, BioImageXD, MedINRIA, SCIRun, ParaView, and others. Furthermore, VTK also provides 3D visualizations for clinical applications such as BrainLAB’s VectorVision surgical guidance system and Zimmer’s prosthesis design and evaluation platform. VTK has been downloaded many hundreds of thousands of times since its initial release in 1993. Considering its broad distribution and prevalent use, it can be argued that VTK has had a greater impact on medical research, and patient care, than any other open-source visualization package. This proposal is in response to the multitude of requests we have been receiving from the VTK medical community. The aims are as follows: 1. Aim 1: Adaptive visualization framework: Produce an integrated framework that supports visualization applications that balance server-side and client-side processing depending on data size, analysis requirements, and the user platform (e.g., phone, tablet, or GPU-enabled desktop). 2. Aim 2: Integrated, interactive applications: Extend VTK to support a diversity of programming paradigms ranging from C++ to JavaScript to Python and associated tools such as Jupyter Notebooks, integrating with emerging technologies such as deep learning technologies. 3. Aim 3: Advanced rendering, including AR/VR: Target shader-based rendering systems and AR/VR libraries that achieve high frame rates with minimal latency for ubiquitous applications that combine low-cost, portable devices such as phones, ultrasound transducers, and other biometric sensors for visually monitoring, guiding, and delivering advanced healthcare. 4. Aim 4: Infrastructure, Outreach, and Validation: Engage the VTK community and the proposed External Advisory Board during the creation and assessment of the proposed work and corresponding modern, digital documentation in the form of videos and interactive web-based content.

Project Narrative The Visualization Toolkit (VTK) is an open source, freely available software library for the interactive display and processing of medical images. It is being used in most major medical imaging research applications, e.g., 3D Slicer and Osirix, and in several commercial medical applications, e.g., BrainLAB’s VectorVision surgical guidance system. VTK development began in 1993 and since then an extensive community of users and developers has grown around it. However, the rapid advancement of cloud computing, GPU hardware, deep learning algorithms, and VR/AR systems require corresponding advances in VTK so that the research and products that depend on VTK continue to deliver leading edge healthcare technologies. With the proposed updates, not only will existing applications continue to provide advanced healthcare, but new, innovative medical applications will also be inspired.