Temporal Bone Imaging and Simulation Research Group

​The “Temporal Bone Imaging and Simulation” research group at the Copenhagen Center for Hearing and Balance, Dept. of Otorhinolaryngology-Head & Neck Surgery, Rigshospitalet, investigates clinical imaging and simulation including virtual reality and 3D-printing for training and patient-specific preparation of temporal bone and middle ear surgery with the aim of improving patient safety and patient outcomes.

​Main research areas

The Visible Ear Simulator – a virtual reality temporal bone surgical simulator

Simulation-based training is a pillar of contemporary surgical education because it allows initial surgical skills acquisition in a patient-free environment prior to supervised patient surgery. Virtual reality (VR) simulation of temporal bone surgery allows ample “dry” training with integrated learning supports and automated feedback and assessment.

The work of our group on The Visible Ear Simulator and others internationally have established a solid evidence-base for VR simulation training of novices. However, as we have developed the simulator further with increased realism of the graphics, multiple training cases and advanced procedures such as cochlear implantation even experienced surgeons can benefit from VR temporal bone surgical simulation.

We actively develop the Visible Ear Simulator and it is one of the most advanced VR simulators available – and it is provided as academic freeware and can be downloaded below.

3D-printing of temporal bone models

The developments within 3D-printing and increased availability and low costs of printers and materials makes it feasible to print temporal bone models for training purposes. In collaboration with the Additive Manufacturing group at DTU, we have researched and streamlined the process of 3D-printing temporal bone models on cheap, commercially available extrusion 3D-printers.

We research how 3D-printed models can be used to best support temporal bone surgical skills acquisition and training and how the models can be used in the clinical context for patient-specific use cases.

Cone-beam CT (CBCT) of the temporal bone and image analysis

CBCT is a relatively new clinical imaging modality, which uses a cone-shaped x-ray beam for digital volume tomography of a small anatomical area. This reduces exposure time and radiation dose at the cost of low contrast resolution but providing excellent spatial resolution. CBCT is mostly used for dentomaxillofacial imaging applications but is also well-suited for imaging of other bony structures such as the temporal bone and paranasal sinuses.

We research how CBCT as “in-office” imaging can be used to improve diagnostics and treatment of middle ear and temporal bone disease. This includes new methods and scan protocols as well as automated image processing. We further have a prospective clinical database to systematically gather data on the value of temporal bone CBCT.

Patient-specific modeling for training and surgical planning

A main research theme for our research group is integrating imaging and simulation, in other words, to use clinical CBCT imaging for patient-specific simulation of temporal bone surgery. This requires substantial image processing to enable accurate simulation – whether VR or 3D-printed – of value to the clinician end-user. 

Patient-specific simulation can potentially be used to prepare the surgeon for the patient’s specific anatomy, for planning and rehearsing the surgical approach and intervention, for guidance during the actual surgery, and in the post-operative evaluation and management. Through research onto patient-specific temporal bone simulation we seek to improve patient treatment and patient safety.

About the research group

The ”Temporal Bone Imaging and Simulation” research group is part of the Copenhagen Hearing and Balance Center (CHBC), which combines clinical and research activities within audiology (hearing), otology (ear disease and surgery), and neurotology (balance and neuro-vestibular surgery) to achieve the highest quality of patient care and excellency in research. Clinical and research resources are shared, which allows us to streamline clinical work-up, treatment, and rehabilitation with access to state-of-the-art research equipment. The CHBC is also partnered with the Danish hearing aid and medico-technical industry for joint ventures in basic and applied research on physiological, diagnostic, therapeutic, and technical aspects of hearing and balance.

Our group manages the department’s cone-beam CT scanner (Morita 3D Accuitomo 170) for clinical imaging of the temporal bone and we are actively researching cone-beam CT for use in otology and neurotology. We also develop software and image processing and visualization routines related to temporal bone imaging as well as educational resources including the Visible Ear Simulator.

We are involved in teaching and training on all levels from pre-graduate to postgraduate including continuing professional education. We also supervise medical students for their Bachelor/Master’s thesis and research semester projects. Topics include the core themes of the research group mentioned above but also more generally simulation, medical education and surgical training, otology and neurotology.

The research group’s activities are coordinated by Dr. Andersen.


  • St​​even A. W. Andersen, MD, PhD, senior researcher.
  • Mads Sølvsten Sørensen, MD, DMSc, professor.
  • Kristianna Mey, MD, PhD, postdoc: “Cone-beam computed tomography scans for the distinction of Inner ear anomalies and cochlear implant electrode positions in PS/NSEVA patients”.
  • Andreas Frithioff, MD, PhD, postdoc: “Automated image analysis of cone-beam CT for clinical decision support in cholesteatoma”. ​
  • Peter Trier Mikkelsen, MSc, PhD-student: “Advancing virtual reality temporal bone simulation for patient-specific simulation and mixed reality perioperative guidance”.
  • Anders Nøhr, MD, PhD-student: “Gamification and certification of virtual reality temporal bone surgical simulation”.
  • Bilal Akram, MD, PhD-student: “Clinical cone-beam CT in the diagnosis and surgical treatment of otosclerosis”.
  • Adam Omari, MD, research student: “Patient-specific 3D-printed temporal bones - setting the stage for surgical training and preoperative rehearsal”.
  • Erik Posselt Gunnersen, MD, research student: “Development of e-learning in audiometry interpretation using the Delphi methodology”. 

Past PhD candidates

Andreas Frithioff, MD, PhD: “3D-printed models for training temporal bone surgery”. Defended his PhD thesis in June 2023.

Martin Frendø, MD, PhD: “Virtual Reality simulation-based training of cochlear implant surgery: perspectives of performance, assessment, and transfer”. Defended his PhD thesis in April 2021.

Technical and administrative support

  • Camilla Buck Campen, biomedical laboratory technician
  • Anthea Terslev-Pedersen, medical secretary

Key collaborators

We collaborate with researchers and research groups nationally and internationally and are always open to new collaborations and research exchanges. Some of our current collaborators include:

Depts. of Biomedical Informatics (Dr. Powell, Mr. Hittle) and Otorhinolaryngology (Dr. Wiet), the Ohio State University, Columbus, Ohio, USA, and Dept. of Otorhinolaryngology (Dr. Wiet), Nationwide Children’s Hospital, Columbus, Ohio.

Additive Manufacturing (Dr. Bue Pedersen), Dept. of Civil and Mechanical Engineering, Danish Technical University, Kgs. Lyngby, Denmark.

Copenhagen Academy for Medical Education and Simulation (CAMES) (Prof. Konge), Center for HR & Education, RegionH, Copenhagen, Denmark.

Funding and support

The research group would like to acknowledge the contribution of resources and research funding from the Dept. of Otorhinolaryngology and Rigshospitalet, as well as external funders (the Independent Research Fund Denmark, the Oticon Foundation, Alfred Benzon Foundation – Programme for Clinical Research, Jascha Foundation​, Toyota-Foundation Denmark).

Services and courses

Cone-beam CT of the temporal bone

We primarily perform cone-beam CT of the temporal bone for clinical work images for our otosurgical team and for research projects approved by the regional ethics committee. Clinical patients are invited to contribute their temporal bone imaging data to our prospective research database. We also have protocols in place for CBCT imaging of other head & neck areas such as paranasal sinuses and larynx for clinical and research projects.

Contact: Dr. Andersen or onh-cbct.rigshospitalet@regionh.dk

Patient information folder


We print models of the temporal bone for training and research purposes. Our philosophy is that training should be affordable, easy to implement and widely available. Therefore, we use cheap extrusion 3D-printers such as Ender-3 Pro and Prusa i3 to print the temporal bone models in-house using Lay-brick (a chalk enriched plastic material) or ABS filament. Details for our “Copenhagen Temporal Bone” model is currently under publication. Currently, we only have the capacity to print sufficient models for our own projects and courses but we are happy to share our expertise to help you start printing you own models. We are working on enabling the export of 3D-print files directly from the Visible Ear Simulator.

Temporal bone training courses

The group contributes to teaching temporal bone surgery through simulation at our international “Copenhagen Otology & Neurotology” course, the national Danish temporal bone course for otorhinolaryngology residents, and in collaboration with our international partners for example the “Temporal Bone Beginner Course” at the Swiss Foundation for Innovation and Training in Surgery (SFITS), Geneva, Switzerland.


The Visible Ear Simulator software

The Visible Ear Simulator (VES) is offered as academic freeware for simulation-based training of temporal bone surgery. VES is an advanced virtual reality (VR) simulator for high-quality rendering of several temporal bone models for evidence-based training of temporal bone surgical procedures such as mastoidectomy and cochlear implantation. The simulator features haptic drilling with force feedback and 3D stereo-graphics – see system requirements below. We are continuously developing the platform and upcoming features include automated final-product assessment of performance, import of cone-beam CT imaging for patient-specific simulation, and export of drilled and undrilled models for 3D-printing.

Download (zip)

System requirements (pdf)

The Visible Ear Simulator instructions and dissection guide​ (pdf)

Performance assessment tools

We have developed and collected educational validity evidence for a number of tools for simulation-based assessment of performance in otology and temporal bone surgery. These include the Modified Welling Scale for final-product assessment of anatomical mastoidectomy with posterior tympanotomy (pdf), structured self-assessment of mastoidectomy performance (pdf), the Cochlear Implant Surgery Assessment Tool (CISAT) (pdf), and an assessment tool for technical skills in handheld otoscopy (pdf).

3D-print files

We have prepared 3D-print files for two temporal bone models, which are available as .stl files for download below. We recommend printing in “transparent” ABS or Lay-brick (PLA with added chalk) for the most realistic drilling experience. Details on the optimal print settings and post-print processes are detailed in an upcoming publication. We are working on an export feature within the Visible Ear Simulator for easy export of 3D-print files for training.

Temporal bone models (stl-files):

Educational research methodology

Our research group is experienced with medical educational research methodology from randomized controlled trials, educational needs assessment and Delphi process, systematic reviews, and various statistical methods. This includes linear mixed models for repeated measurement statistics and Generalizability Theory for reliability analysis, and for the latter, we are actively contributing to the G_String Legacy software and GitHub community in collaboration with Ralph Bloch.

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