Research interests: Data mining, machine learning, software engineering, finite element modelling of soft tissue biomechanics, FEM contact modelling, point cloud registration
Current research: Large scale analysis of clinical image data.
About me: I did an MSc in computer science majoring in computational science with ETH Zurich that I finished in 2008. In 2010, I received my second MSc in medical image computing from UCL. I have been a research assistant and part-time PhD student with CMIC since 2011.
What I like about my job: My current project offers a wide variety of tasks, requiring skills from some quite different areas engineering. This has allowed me to broaden my horizon and especially learn new skills in machine learning.
Publications (1st Author):
1. Johnsen SF, Thompson S, Clarkson MJ, Modat M, Song Y, Totz J, Gurusamy K, Davidson B, Taylor ZA, Hawkes DJ, Ourselin S (2015): "Database-based estimation of liver deformation under pneumoperitoneum for surgical image-guidance and simulation"; MICCAI 2015, Lecture Notes in Computer Science; DOI: 10.1007/978-3-319-24571-3_54
2. Johnsen, SF, Taylor, ZA, Han, L, Hu, Y, Clarkson, MJ, Hawkes, DJ, Ourselin, S (2015): "Detection and modelling of contacts in explicit finite-element simulation of soft tissue biomechanics"; Int J Comput Assist Radiol Surg; DOI: 10.1007/s11548-014-1142-5
3. Johnsen SF, Taylor ZA, Clarkson MJ, Hipwell J, Modat M, Eiben B, Han L, Hu Y, Mertzanidou T, Hawkes DJ, Ourselin S (2014): "NiftySim: A GPU-based nonlinear finite element package for simulation of soft tissue biomechanics"; Int J Comput Assist Radiol Surg; DOI: 10.1007/s11548-014-1118-5
4. Johnsen S, Taylor Z, Thompson S; Davidson B, Hu M, Clarkson M, Hawkes S, Ourselin S (2012): "Explicit Contact Modelling for Surgical Computer Guidance and Simulation". SPIE Medical Imaging, Feb. 2012
5. Johnsen S, Taylor Z, Thompson S, Davidson B, Hu M, Hawkes D, Ourselin S (2011): "Explicit FEM Tissue Simulation for Surgical Image-Guidance". Living Imaging; 2011
1. Yi Song, Johannes Totz, Steve Thompson, Stian Johnsen, Dean Barratt, Crispin Schneider, Kurinchi Gurusamy, Brian Davidson, Sébastien Ourselin, David Hawkes, Matthew J. Clarkson (2015): "Locally rigid, vessel-based registration for laparoscopic liver surgery"; International Journal of Computer Assisted Radiology and Surgery; DOI: 10.1007/s11548-015-1236-8
2. Clarkson MJ, Zombori G, Thompson S, Totz J, Song Y, Espak M, Johnsen S, Hawkes D, Ourselin S (2014): "The NifTK Software Platform for Image Guided Interventions". International Journal of Computer Assisted Radiology and Surgery; accepted.
3. Mertzanidou T, Hipwell J, Johnsen S, Han L, Eiben B, Taylor Z, Ourselin S, Huisman H, Mann R, Bick U, Karssemeijer N, Hawkes D (2014) "MRI to X-ray mammography intensity-based registration with simultaneous optimisation of pose and biomechanical transformation parameters". Med Image Anal , 18 (4) 674 - 683.