Prof. Dr. Christian Hansen

@inproceedings{mielke_gesturing_2025,

title = {Gesturing Towards Efficient Robot Control: Exploring Sensor Placement and Control Modes for Mid-Air Human-Robot Interaction},

author = {T Mielke and F Heinrich and C Hansen},

doi = {10.1109/ICRA55743.2025.11127519},

year  = {2025},

date = {2025-09-02},

urldate = {2025-01-01},

booktitle = {2025 IEEE International Conference on Robotics and Automation (ICRA)},

abstract = {While collaborative robots effectively combine robotic precision with human capabilities, traditional control methods such as button presses or hand guidance can be slow and physically demanding. This has led to an increasing interest in natural user interfaces that integrate hand gesturebased interactions for more intuitive and flexible robot control. Therefore, this paper systematically explores mid-air robot control by comparing position and rate control modes with different state-of-the-art and novel sensor placements. A user study was conducted to evaluate each combination in terms of accuracy, task duration, perceived workload, and physical exertion. Our results indicate that position control is more efficient than rate control. Traditional desk-mounted sensors can provide a good balance between accuracy and comfort. However, robot-mounted sensors are a viable alternative for short-term, accurate control with less spatial requirements. Legmounted sensors, while comfortable, pose challenges to handeye coordination. Based on these findings, we provide design implications for improving the usability and comfort of midair human-robot interaction. Future research should extend this evaluation to a wider range of tasks and environments.},

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}

@inproceedings{mielke_enhancing_2025,

title = {Enhancing AR-to-Robot Registration Accuracy: A Comparative Study of Marker Detection Algorithms and Registration Parameters},

author = {T Mielke and F Heinrich and C Hansen},

doi = {10.1109/ICRA55743.2025.11128039},

year  = {2025},

date = {2025-09-02},

urldate = {2025-09-02},

booktitle = {2025 IEEE International Conference on Robotics and Automation (ICRA)},

publisher = {IEEE},

abstract = {Augmented Reality (AR) offers potential for enhancing human-robot collaboration by enabling intuitive interaction and real-time feedback. A crucial aspect of AR-robot integration is accurate spatial registration to align virtual content with the physical robotic workspace. This paper systematically investigates the effects of different tracking techniques and registration parameters on AR-to-robot registration accuracy, focusing on paired-point methods. We evaluate four marker detection algorithms - ARToolkit, Vuforia, ArUco, and retroreflective tracking - analyzing the influence of viewing distance, angle, marker size, point distance, distribution, and quantity. Our results show that ARToolkit provides the highest registration accuracy. While larger markers and positioning registration point centroids close to target locations consistently improved accuracy, other factors such as point distance and quantity were highly dependent on the tracking techniques used. Additionally, we propose an effective refinement method using point cloud registration, significantly improving accuracy by integrating data from points recorded between registration locations. These findings offer practical guidelines for enhancing AR-robot registration, with future work needed to assess the transferability to other AR devices and robots.},

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@inproceedings{Joeres.2025,

title = {The necessity of parallel needle placement for tumor ablation using irreversible electroporation: a myth?},

author = {F Joeres and T Paetz and C Hansen and A Schenk},

url = {https://link.springer.com/article/10.1007/s11548-025-03373-6},

doi = {https://doi.org/10.1007/s11548-025-03373-6},

year  = {2025},

date = {2025-05-29},

urldate = {2025-05-29},

booktitle = {CARS 2025—Computer Assisted Radiology and Surgery Proceedings of the 39th International Congress and Exhibition Berlin, Germany, June 17–20, 2025

},

pages = {90–91},

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pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{mielke_virtual_2025,

title = {Virtual Studies, Real Results? Assessing the Impact of Virtualization on Human-Robot Interaction},

author = {T Mielke and M Allgaier and D Schott and C Hansen and F Heinrich},

url = {https://dl.acm.org/doi/10.1145/3706599.3719724},

doi = {10.1145/3706599.3719724},

isbn = {979-8-4007-1395-8},

year  = {2025},

date = {2025-04-01},

urldate = {2025-04-01},

booktitle = {Proceedings of the Extended Abstracts of the CHI Conference on Human Factors in Computing Systems},

pages = {1–8},

publisher = {ACM},

address = {Yokohama Japan},

abstract = {Extended Reality (XR) shows potential for human-centered evaluation of real-world scenarios and could improve efficiency and safety in robotic research. However, the validity of XR Human-Robot Interaction (HRI) studies remains underexplored. This paper investigates the transferability of HRI studies across virtualization levels for three tasks. Our results indicate XR study validity is task-specific, with task virtualization as a key influencing factor. Partially virtualized settings with virtual tasks and a real robot, as well as fully virtualized setups with a simulated robot, yielded results comparable to real setups for pick-and-place and robotic ultrasound. However, for precision-dependent peg-in-hole, differences were observed between real and virtualized conditions regarding completion time, perceived workload, and ease. Demonstrating the task dependency of XR transferability and comparing virtualization levels, our work takes an important step in assessing XR study validity. Future work should isolate factors affecting transferability and assess relative validity in the absence of absolute validity.},

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}

@inproceedings{schwenderling_teach_2025,

title = {Teach Me Where to Look: Dual-task Attention Training in Augmented Reality},

author = {L Schwenderling and M Schotte and F Joeres and F Heinrich and L Hanke and F Huettl and T Huber and C Hansen},

url = {https://dl.acm.org/doi/10.1145/3706599.3720198},

doi = {10.1145/3706599.3720198},

isbn = {979-8-4007-1395-8},

year  = {2025},

date = {2025-04-01},

urldate = {2025-04-01},

booktitle = {Proceedings of the Extended Abstracts of the CHI Conference on Human Factors in Computing Systems},

pages = {1–8},

publisher = {ACM},

address = {Yokohama Japan},

abstract = {Regular eye contact is essential in medicine to recognize signs of pain. However, it is difficult to remember this during training as attention is tied up in learning. While augmented reality (AR) has shown promising results for medical education, there is no training for attention allocation yet. Therefore, three auditory and three visual attention guidance tools in AR are evaluated for their use in medical dual-task training settings. In expert reviews with six participants in human-computer interaction and medical didactics, advantages, disadvantages, and refinements for the cues were developed. For visual cues, an overt but less occluding cue was preferred for constant visibility of the primary task. A more diegetic cue design was proposed for the auditory cues to use a patient simulation as a reminder of the regular face glance. In general, several cues were found to be suitable for gaze guidance training, requiring only minor changes for improvement.},

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}

@inproceedings{heinrich_you_2025,

title = {Do You See What I See? Evaluating Relative Depth Judgments Between Real and Virtual Projections},

author = {F Heinrich and D Schott and L Schwenderling and C Hansen},

url = {https://doi.org/10.1145/3706599.3720157},

doi = {10.1145/3706599.3720157},

isbn = {979-8-4007-1395-8},

year  = {2025},

date = {2025-04-01},

urldate = {2025-04-01},

booktitle = {Proceedings of the Extended Abstracts of the CHI Conference on Human Factors in Computing Systems},

pages = {1–8},

publisher = {Association for Computing Machinery},

address = {New York, NY, USA},

series = {CHI EA '25},

abstract = {Projector-based augmented reality (AR) is promising in different domains with less issues in discomfort or shortage of space. However, due to limitations like high costs and cumbersome calibration, this AR modality remains underused. To address this problem, a stereoscopic projector-based AR simulation was implemented for a cost-effective video see-through AR headset. To evaluate the validity of this simulation, a relative depth judgment experiment was conducted to compare this method with a physical projection system. Consistent results suggest that a known interaction effect between visualization and disparity mode could be successfully reproduced using both the physical projection and the virtual simulation. In addition, first findings indicate that there are no significant differences between these projection modalities. The results indicate that other perception-related effects observed for projector-based AR may also be applicable to virtual projection simulations and that future findings determined using only these simulations may also be applicable to real projections.},

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@inproceedings{herbrich_prototype_2025,

title = {Prototype development of a cross-reality digital twin ecosystem: the web, open source and open data},

author = {W Herbrich and P Zittlau and F Joeres and C Hansen},

url = {https://ieeexplore.ieee.org/abstract/document/10972895},

doi = {10.1109/VRW66409.2025.00100},

year  = {2025},

date = {2025-03-01},

urldate = {2025-03-01},

booktitle = {2025 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)},

pages = {459–462},

abstract = {This work contributes to a broader initiative aimed at transforming a former industrial port area into a dynamic Knowledge Transfer Space (KTS). To support this transformation, we explore the development of a cross-reality (CR) digital twin of the port area, which integrates user interfaces with varying degrees of virtuality. We evaluate different web technologies, focusing on the balance between accessibility, immersion, scalability, and performance. By comparing client-side rendering with pixel streaming approaches, we aim to identify suitable solutions for prototyping a CR digital twin ecosystem. The development of a prototype is ongoing, based on a client-side rendering approach. The outcomes contribute to developing an open and transferable CR digital twin applicable to similar urban projects in other cities.},

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}

@inproceedings{allgaier_impact_2025,

title = {Impact of Input and Output Devices on a Virtual Ultrasound Training},

author = {M Allgaier and E Dangszat and F Huettl and L Hanke and T Huber and B Preim and C Hansen},

url = {https://ieeexplore.ieee.org/document/10972939/},

doi = {10.1109/VRW66409.2025.00191},

isbn = {979-8-3315-1484-6},

year  = {2025},

date = {2025-03-01},

urldate = {2025-03-01},

booktitle = {2025 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)},

pages = {937–941},

publisher = {IEEE},

address = {Saint Malo, France},

abstract = {Performing ultrasound requires mental skills that have to be trained hands on. Virtual simulations can be employed to provide novice surgeons with a safe training environment prior to performing ultrasound on the patient. For both input and output there is a wide range of devices that are used in existing ultrasound simulations. Because the devices have their limitations and benefits regarding realism, costs, and access, we compared three technical setups: desktop with mouse interaction, desktop with a haptic device, and virtual reality with a haptic device. In a user study with 19 participants we investigated the usability and assessed qualitative user feedback in a semi-structured interview. Significant differences regarding usability and training time were found between both versions with the haptic device and the desktop with mouse version. Based on the feedback, using a haptic device seems to be more relevant than the two output devices in this training case.},

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@inproceedings{schreiter_exploring_2025,

title = {Exploring Interaction Concepts for the Manipulation of a Collaborative Robot: A Comparative Study},

author = {J Schreiter and T Mielke and M Georgiades and M Pech and C Hansen and F Heinrich},

year  = {2025},

date = {2025-01-01},

urldate = {2025-01-01},

booktitle = {Proceedings of the 2025 ACM/IEEE International Conference on Human-Robot Interaction},

pages = {55–64},

publisher = {IEEE Press},

address = {Melbourne, Australia},

series = {HRI '25},

abstract = {Robotic systems have the potential to enhance a wide range of domains, such as medical workflows, by automating individual steps of complex processes. However, human-robot interaction (HRI) is of critical importance, as effective collaboration between humans and robots is essential even in highly automated environments. Recent research has predominantly focused on the development of interaction methods rather than systematically comparing existing approaches. Therefore, we conducted a user study (n=20) to compare different HRI concepts for end effector manipulation combined with clutching mechanisms for manipulation activation in an alignment task using the example of robotic ultrasound (US). Manipulation methods included hand-guiding, teleoperation, and touchless interaction, while clutching mechanisms were realized through hand, voice, and foot interaction. The results indicate advantages of hand-guiding for manipulation. While no significant differences were observed between clutching mechanisms, strong evidence suggests comparable performance across these modalities. Notably, significant interaction effects on perceived workload reveal that the optimal clutching mechanism depends on the selected manipulation technique. This work underscores the critical importance of selecting appropriate HRI concepts and understanding the dependencies of manipulation techniques with clutching mechanisms. While our study included the usage of a robotic US, the insights gained are broadly transferable across various domains involving robotic manipulation tasks in human-robot collaboration.},

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}

@inproceedings{bashkanov_augmenting_2025,

title = {Augmenting Prostate MRI Dataset with Synthetic Volumetric Images from Zone-Conditioned Diffusion Generative Model},

author = {O Bashkanov and M Rak and L Engelage and C Hansen},

editor = {A Mukhopadhyay and Ilkay Oksuz and Sandy Engelhardt and Dorit Mehrof and Yixuan Yuan},

doi = {10.1007/978-3-031-72744-3_16},

isbn = {978-3-031-72744-3},

year  = {2025},

date = {2025-01-01},

urldate = {2025-01-01},

booktitle = {Deep Generative Models},

pages = {160–168},

publisher = {Springer Nature Switzerland},

address = {Cham},

abstract = {The need for artificial intelligence (AI)-driven computer-assist ed diagnosis (CAD) tools drives up the demand for large high-quality datasets in medical imaging. However, collecting the necessary amount of data is often impractical due to patient privacy concerns or restricted time for medical annotation. Recent advances in generative models in medical imaging with a focus on diffusion-based techniques could provide realistic-looking synthetic samples as a supplement for real data. In this work, we study whether synthetic volumetric MRIs generated by the diffusion model can be used to train downstream models, e.g., semantic segmentation. We can create an arbitrarily large dataset with ground truth by conditioning the diffusion model with a segmentation mask. Thus, the additional synthetic data can be used to control the dataset diversity. Experiments revealed that downstream tasks profit from additional synthetic data. However, the effect will eventually diminish when sufficient real samples are available. We showcase the strength of the synthetic data and provide practical recommendations for using the generated data in zonal prostate segmentation.},

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}

@inproceedings{batz2025enhancing,

title = {Enhancing Public Awareness of Air Quality: Evaluating Communication Strategies and Design Prototypes Using a Design-Based Implementation Research Approach},

author = {V Batz and V B Liedtke and P Lameski and V Trajkovik and S Hußlein and C Hansen and M A Herzog},

url = {https://link.springer.com/chapter/10.1007/978-3-031-93221-2_1},

year  = {2025},

date = {2025-01-01},

urldate = {2025-01-01},

booktitle = {International Conference on Human-Computer Interaction},

pages = {3–25},

organization = {Springer},

abstract = {Despite the health risks associated with air pollution and the availability of data, public awareness of air quality remains limited. This paper examines communication strategies to enhance awareness in Germany and North Macedonia. Using the Design-Based Implementation Research approach, literature reviews, stakeholder interviews and surveys were conducted with 307 participants to identify knowledge gaps and effective methods.



Three citizen workshops led to the development and evaluation of five design prototypes, including an interactive installation (“Pollution Booth”), a VR application (“Visible Particulate Matter”), and a gamified learning experience (“End Game”). These prototypes addressed information accessibility, data representation, and environmentally conscious behavior. The results show that region-specific communication, interactive designs, and passive information methods in public spaces significantly improve the perception and understanding of air pollution data. Gamified approaches, such as the “End Game” prototype, were particularly effective in educating children about air pollution.



Thirty-two requirements for effective educational strategies were identified, including simplified data visualization, reduced content, and personalized information. The findings highlight the importance of local and personalized approaches, as well as methods for collective knowledge sharing, in promoting awareness and environmentally friendly behavior. Future work should further explore the long-term engagement and sustainable impact of such communication strategies.},

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}

@inproceedings{joeres_concept_2024,

title = {Concept development of a cross-reality ecosystem for urban knowledge transfer spaces},

author = {F Joeres and P Zittlau and W Herbrich and F Heinrich and G Rose and C Hansen},

url = {https://ieeexplore.ieee.org/abstract/document/10765174},

doi = {10.1109/ISMAR-Adjunct64951.2024.00043},

year  = {2024},

date = {2024-10-01},

urldate = {2024-10-01},

booktitle = {2024 IEEE International Symposium on Mixed and Augmented Reality Adjunct (ISMAR-Adjunct)},

pages = {166–169},

abstract = {This paper presents the development of a cross-reality (CR) ecosystem designed for an urban knowledge transfer space (KTS) in a post-industrial urban environment. The project is part of a larger initiative aimed at transforming a former industrial river port into a dynamic KTS, facilitating interactions between scientific, commercial, residential, and cultural stakeholders. Our research explores the potential of multimodal mixed reality (XR) technologies to enhance engagement with the content and stakeholders of the KTS. Through a three-phase process, we identified key stakeholders and their target audiences, selected appropriate XR technologies, and developed initial use cases that integrate web applications, mobile augmented reality (AR), and XR head-mounted displays. The preliminary findings indicate that these technologies can effectively cater to diverse user groups, providing different levels of virtuality and interaction. However, challenges remain, particularly in stakeholder engagement and the evolving nature of the KTS initiative. Ongoing work includes the development of a Web-XR-based prototype, which will be iteratively refined to better meet user needs and adapt to future technological advancements. This research contributes to the understanding of how CR technologies can be employed in urban transformation processes, offering insights into the design of flexible and scalable CR ecosystems.},

note = {ISSN: 2771-1110},

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tppubtype = {inproceedings}

}

@inproceedings{schott_ar-based_2024,

title = {An AR-Based Multi-User Learning Environment for Anatomy Seminars},

author = {D Schott and M Kunz and J Mandel and L Schwenderling and R Braun-Dullaeus and C Hansen},

url = {https://ieeexplore.ieee.org/document/10536568/},

doi = {10.1109/VRW62533.2024.00271},

isbn = {979-8-3503-7449-0},

year  = {2024},

date = {2024-03-01},

urldate = {2024-03-01},

booktitle = {2024 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)},

pages = {949–950},

publisher = {IEEE},

address = {Orlando, FL, USA},

abstract = {Understanding the intricate and rapid changes in shape during em-bryonic formation is vital for medical students. Using the example of embryonic human heart development, we introduce an AR-based multi-user approach to enhance understanding and foster a participatory learning environment. Through a user-centered approach, we created a prototype accommodating two player roles and enabling multi-modal inputs to encourage dynamic group discussions. We in-vited four anatomy experts to evaluate three system configurations in an interdisciplinary workshop to assess the feasibility of integration into anatomy seminars. The gathered data and feedback indicate the potential of our collaborative concept for integration into the medical curriculum.},

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}

@inproceedings{schwenderling_novel_2024,

title = {A Novel Framework for Hand Visualization in Web-Based Collaborative XR},

author = {L Schwenderling and W Herbrich and F Joeres and C Hansen},

url = {https://ieeexplore.ieee.org/document/10536317/},

doi = {10.1109/VRW62533.2024.00010},

isbn = {979-8-3503-7449-0},

year  = {2024},

date = {2024-03-01},

urldate = {2024-03-01},

booktitle = {2024 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)},

pages = {18–23},

publisher = {IEEE},

address = {Orlando, FL, USA},

abstract = {Many extended reality (XR) applications are platform-specific, making accessibility and cross-platform collaboration difficult. Web-based collaborative XR can enhance adoption of XR technologies, using the browser as a platform-independent interface. However, challenges arise from the browser environment, such as performance limitations. To this end, we present a WebXR-based framework for hand interaction in cross-platform collaboration in XR. A network structure and methods for collaborative and individual object manipulation complement the integrated hand tracking. Three different fidelity levels to represent the hands of remote users were implemented to accommodate different performance capabilities. Concepts ranged from virtual hands to discrete poses with abstract objects. A sample application was implemented with a puzzle task. Two users collaborated in the browsers of the Microsoft HoloLens 2 and the Meta Quest 2. Qualitative and quantitative data on user performance (n=9), and frame rate recordings (n=1) were collected. All users were able to solve the puzzle together quickly and intu-itively. The Quest environment was preferred, as there were more performance issues with the HoloLens. Hand interaction was well-received and proved to be sufficient as the only form of communication. Simpler representations of the hands lead to a higher frame rate, whereby the effects were device-dependent. The impact on task performance was low. Hand interaction enables an intuitive exchange of objects and basic communication in cross-platform collaboration via browsers. Depending on the XR environment, however, device-specific performance limitations must be taken into account by modulating the amount of data and rendering effort.},

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@inproceedings{schott_stand_2024,

title = {Stand Alone or Stay Together: An In-situ Experiment of Mixed-Reality Applications in Embryonic Anatomy Education},

author = {D Schott and M Kunz and F Heinrich and J Mandel and A Albrecht and R Braun-Dullaeus and C Hansen},

url = {https://dl.acm.org/doi/10.1145/3641825.3687706},

doi = {10.1145/3641825.3687706},

isbn = {979-8-4007-0535-9},

year  = {2024},

date = {2024-01-01},

urldate = {2024-01-01},

booktitle = {Proceedings of the 30th ACM Symposium on Virtual Reality Software and Technology},

pages = {1–11},

publisher = {Association for Computing Machinery},

address = {New York, NY, USA},

series = {VRST '24},

abstract = {Where traditional media and methods reach their limits in anatomy education, mixed-reality (MR) environments can provide effective learning support because of their high interactivity and spatial visualization capabilities. However, the underlying design and pedagogical requirements are as diverse as the technologies themselves. This paper examines the effectiveness of individual- and collaborative learning environments for anatomy education, using embryonic heart development as an example. Both applications deliver the same content using identical visualizations and hardware but differ in interactivity and pedagogical approach. The environments were evaluated in a user study with medical students (n = 90) during their examination phase, assessing usability, user experience, social interaction/co-presence, cognitive load, and personal preference. Additionally, we conducted a knowledge test before and after an MR learning session to determine educational effects compared to a conventional anatomy seminar. Results indicate that the individual learning environment was generally preferred. However, no significant difference in learning effectiveness could be shown between the conventional approach and the MR applications. This suggests that both can effectively complement traditional seminars despite their different natures. Our study contributes to understanding how different MR settings could be tailored for anatomical education.},

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@inproceedings{wagnerberger_empowering_2024,

title = {Empowering Patients: Improve Gender-Sensitive Medical Knowledge Through Interactive Edutainment},

author = {D Wagnerberger and D Schott and L Schwenderling and C Hansen and D Schumacher},

url = {https://dl.acm.org/doi/10.1145/3679318.3685500},

doi = {10.1145/3679318.3685500},

isbn = {979-8-4007-0966-1},

year  = {2024},

date = {2024-01-01},

urldate = {2024-01-01},

booktitle = {Proceedings of the 13th Nordic Conference on Human-Computer Interaction},

pages = {1–12},

publisher = {Association for Computing Machinery},

address = {New York, NY, USA},

series = {NordiCHI '24},

abstract = {Disregarding crucial gender-specific differences and potential risks in medicine leads to widespread gender inequalities. This paper introduces interactive edutainment concepts developed through a user-centered design approach to raise awareness of gender medicine. An interactive exhibition course and an accompanying deck of cards provide an engaging and sensitizing experience of medical gender inequalities. Qualitative feedback, self-assessment, and user experience and behavior were evaluated during a public display of the concepts (n=14). The results highlight the potential of our playful approach to raising awareness among the public as well as health-related professionals, paving new ways for communication and empowerment of patients of all genders. We believe these insights have broader applicability across various domains, supporting efforts to address all forms of inequality.},

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@inproceedings{polenz_simulating_2024,

title = {Simulating projective Augmented Reality Visualizations in Virtual Reality: Is VR a feasible Environment for medical AR Evaluations?},

author = {L Polenz and F Joeres and C Hansen and F Heinrich},

url = {https://doi.org/10.1145/3613905.3650843},

doi = {10.1145/3613905.3650843},

isbn = {979-8-4007-0331-7},

year  = {2024},

date = {2024-01-01},

urldate = {2024-01-01},

booktitle = {Extended Abstracts of the CHI Conference on Human Factors in Computing Systems},

pages = {1–8},

publisher = {Association for Computing Machinery},

address = {New York, NY, USA},

series = {CHI EA '24},

abstract = {Augmented Reality (AR) has demonstrated potential in medical applications, such as enhancing surgical navigation. However, evaluating medical AR visualizations entails high costs and effort to provide suitable hardware solutions. This is particularly crucial in projective AR, as these systems require several error-prone calibration and registration steps. This work investigates the suitability of Virtual Reality (VR) as a cost-effective and controlled study environment for evaluating projective AR visualizations. A virtual twin of a real laboratory environment was created, and a user study comparing two needle navigation visualizations was conducted. The study simulated identical experiments in both AR and VR to assess if similar results would emerge. Our findings indicate that both AR and VR experiments exhibited comparable effects in terms of performance and workload of both needle insertion visualizations. This study serves as a preliminary step in demonstrating the feasibility of using VR as an evaluation environment for projective AR visualizations.},

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@inproceedings{allgaier_gamification_2024,

title = {Gamification Concepts for a VR-based Visuospatial Training for Intraoperative Liver Ultrasound},

author = {M Allgaier and F Huettl and L Hanke and T Huber and B Preim and S Saalfeld and C Hansen},

url = {https://doi.org/10.1145/3613905.3650736},

doi = {10.1145/3613905.3650736},

isbn = {979-8-4007-0331-7},

year  = {2024},

date = {2024-01-01},

urldate = {2024-01-01},

booktitle = {Extended Abstracts of the CHI Conference on Human Factors in Computing Systems},

pages = {1–8},

publisher = {Association for Computing Machinery},

address = {New York, NY, USA},

series = {CHI EA '24},

abstract = {Gamification is widely used due to its positive influence on learning by adding emotions and steering behavior. In medical VR training applications, the use of gamification is rare, and when it is implemented, it often lacks thoughtful design decisions and empirical evaluation. Using a VR-based training for intraoperative ultrasound for liver surgery, we analyzed game elements regarding their suitability and examined two in more detail: difficulty levels and a kit, where the user has to assemble a virtual liver using US. In a broad audience study, levels achieved significantly better results regarding enjoyment. Qualitative feedback from medical students directly comparing the elements revealed that they prefer the kit as well as levels for training. Our studies indicate that levels and the more interactive kit improve the learning experience, which could also be taken as a basis for similar VR-based medical training applications.},

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@inproceedings{bashkanov_automatic_2024,

title = {Automatic Patient-level Diagnosis of Prostate Disease with Fused 3D MRI and Tabular Clinical Data},

author = {O Bashkanov and M Rak and L Engelage and C Hansen},

url = {https://proceedings.mlr.press/v227/bashkanov24a.html},

year  = {2024},

date = {2024-01-01},

urldate = {2024-01-01},

booktitle = {Medical Imaging with Deep Learning},

pages = {1225–1238},

publisher = {PMLR},

abstract = {Computer-aided diagnosis systems for automatic prostate cancer diagnosis can provide radiologists with decision support during image reading. However, in this case, patient-relevant information often remains unexploited due to the greater focus on the image recognition side, with various imaging devices and modalities, while omitting other potentially valuable clinical data. Therefore, our work investigates the performance of recent methods for the fusion of rich image data and heterogeneous tabular data. Those data may include patient demographics as well as laboratory data, e.g., prostate-specific antigen (PSA). Experiments on the large dataset (3800 subjects) indicated that when using the fusion method with demographic data in clinically significant prostate cancer (csPCa) detection tasks, the mean area under the receiver operating characteristic curve (ROC AUC) has improved significantly from 0.736 to 0.765. We also observed that the naïve concatenation performs similarly or even better than the textbackslashmboxstate-of-the-art fusion modules. We also achieved better prediction quality in grading prostate disease by including more samples from longitudinal PSA profiles in the tabular feature set. Thus, by including the three last PSA samples per patient, the best-performing model has reached AUC of 0.794 and a quadratic weighted kappa score (QWK) of 0.464, which constitutes a significant improvement compared with the image-only method, with ROC AUC of 0.736 and QWK of 0.342.},

note = {ISSN: 2640-3498},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{schott_is_2023,

title = {Is this the vReal Life? Manipulating Visual Fidelity of Immersive Environments for Medical Task Simulation},

author = {D Schott and F Heinrich and L Stallmeister and J Moritz and B Hensen and C Hansen},

url = {https://ieeexplore.ieee.org/document/10316533/},

doi = {10.1109/ISMAR59233.2023.00134},

isbn = {979-8-3503-2838-7},

year  = {2023},

date = {2023-10-01},

urldate = {2023-10-01},

booktitle = {2023 IEEE International Symposium on Mixed and Augmented Reality (ISMAR)},

pages = {1171–1180},

publisher = {IEEE},

address = {Sydney, Australia},

abstract = {Recent developments and research advances contribute to an ever-increasing trend towards quality levels close to what we experience in reality. In this work, we investigate how different degrees of these quality characteristics affect user performance, qualia of user experience (UX), and sense of presence in an example medical task. To this end, a two-way within-subjects design user study was conducted, in which three different levels of visual fidelity were compared. In addition, two different interaction modalities were considered: (1) the use of conventional VR controllers and (2) natural hand interaction using 3D-printed, spatially-registered replicas of medical devices, to interact with their virtual representations. Consistent results indicate that higher degrees of visual fidelity evoke a higher sense of presence and UX. However, user performance was less affected. Moreover, no differences were detected between both interaction modalities for the examined task. Future work should investigate the discovered interaction effects between quality levels and interaction modalities in more detail and examine whether these results can be reproduced in tasks that require more precision. This work provides insights into the implications to consider when studying interactions in VR and paves the way for investigations into early phases of medical product development and workflow analysis.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{mielke_interactive_2023,

title = {Interactive Registration Methods for Augmented Reality in Robotics: A Comparative Evaluation},

author = {T Mielke and F Joeres and D Schott and C Hansen},

url = {https://ieeexplore.ieee.org/document/10322246/},

doi = {10.1109/ISMAR-Adjunct60411.2023.00109},

isbn = {979-8-3503-2891-2},

year  = {2023},

date = {2023-10-01},

urldate = {2023-10-01},

booktitle = {2023 IEEE International Symposium on Mixed and Augmented Reality Adjunct (ISMAR-Adjunct)},

pages = {501–506},

publisher = {IEEE},

address = {Sydney, Australia},

abstract = {Augmented Reality (AR) visualization has shown potential for supporting intuitive and efficient human-robot interaction in a range of tasks. Since all these tasks are spatially related to the robot, the precise positioning of the AR content is critical to the applicability. However, most research has primarily focused on developing visualizations rather than exploring methods for aligning AR content in the robotic workspace. This paper aims to bridge this gap by implementing and comparing different interactive registration methods, including two point-based and one manual approach. We comparatively evaluated these registration methods in a user study (n=21), measuring registration accuracy, duration, and subjective user feedback. Our results indicate that the point-based methods outperform the manual approach in terms of both accuracy and perceived workload. Furthermore, participants achieved significantly faster performance with a point-based approach using physically defined registration points compared to a point-based approach using markers attached to the robot.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{allgaier_livrsono_2023,

title = {LiVRSono - Virtual Reality Training with Haptics for Intraoperative Ultrasound},

author = {M Allgaier and F Huettl and L Hanke and H Lang and T Huber and B Preim and S Saalfeld and C Hansen},

url = {https://ieeexplore.ieee.org/document/10316488/},

doi = {10.1109/ISMAR59233.2023.00114},

isbn = {979-8-3503-2838-7},

year  = {2023},

date = {2023-10-01},

urldate = {2023-10-01},

booktitle = {2023 IEEE International Symposium on Mixed and Augmented Reality (ISMAR)},

pages = {980–989},

publisher = {IEEE},

address = {Sydney, Australia},

abstract = {One of the biggest challenges in using ultrasound (US) is learning to create a spatial mental model of the interior of the scanned object based on the US image and the probe position. As intraoperative ultrasound (IOUS) cannot be easily trained on patients, we present LiVRSono, an immersive VR application to train this skill. The immersive environment, including an US simulation with patientspecific data as well as haptics to support hand-eye coordination, provides a realistic setting. Four clinically relevant training scenarios were identified based on the described learning goal and the workflow of IOUS for liver. The realism of the setting and the training scenarios were evaluated with eleven physicians, of which six participants are experts in IOUS for liver and five participants are potential users of the training system. The setting, handling of the US probe, and US image were considered realistic enough for the learning goal. Regarding the haptic feedback, a limitation is the restricted workspace of the input device. Three of the four training scenarios were rated as meaningful and effective. A pilot study regarding learning outcome shows positive results, especially with respect to confidence and perceived competence. Besides the drawbacks of the input device, our training system provides a realistic learning environment with meaningful scenarios to train the creation of a mental 3D model when performing IOUS. We also identified important improvements to the training scenarios to further enhance the training experience.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{schott_uuxr-framework_2023,

title = {The UUXR-Framework: A Draft Classification for Using Extended Reality in Usability and User Experience Research},

author = {D Schott and J Moritz and C Hansen and F Joeres},

url = {https://ieeexplore.ieee.org/document/10322234/},

doi = {10.1109/ISMAR-Adjunct60411.2023.00100},

isbn = {979-8-3503-2891-2},

year  = {2023},

date = {2023-10-01},

urldate = {2023-10-01},

booktitle = {2023 IEEE International Symposium on Mixed and Augmented Reality Adjunct (ISMAR-Adjunct)},

pages = {460–465},

publisher = {IEEE},

address = {Sydney, Australia},

abstract = {Conducting human-centered evaluations in extended reality (XR) environments is a growing trend in user research and usability engineering. However, there has been little to no systematic investigation of the emerging methods in this field published to date. The motivation behind our work is to explore and classify strategies and methods for utilizing XR technologies in the context of usability and user experience (UUX) activities. This paper proposes a draft classification framework for the use of XR technologies in UUX activities, combining an informal exploration of relevant literature with established UUX methods. Within this framework, we propose 12 dimensions that we consider potentially relevant for determining whether and how the use of XR technologies can benefit product development and user research. To evaluate the structure and phrasing of our proposed dimensions, we conducted an initial evaluation with UUX professionals (N = 11). We believe that our dimensions form an early-stage foundation for future guidelines aimed at UUX researchers. The framework serves as a tool for assessing different levels of virtualization in UUX work and facilitating knowledge transfer between academia and industry.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{chheang_virtual_2023,

title = {Virtual Resection Planning using Bezier Surface Interactions in Collaborative VR Environments},

author = {V Chheang and R Bruggernann and B Preim and C Hansen},

url = {https://ieeexplore.ieee.org/document/10108900},

doi = {10.1109/VRW58643.2023.00041},

year  = {2023},

date = {2023-03-01},

urldate = {2023-03-01},

booktitle = {2023 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (VRW)},

pages = {166–169},

abstract = {The use of virtual reality (VR) has been proposed for collaborative planning or training scenarios to aid surgeons in preparing surgical interventions. In this paper, we explore the usage of cubic Bezier surfaces and their respective interactions in collaborative VR environments to define atypical resection surfaces for planning abdominal organ tumor resections. We conducted a pilot study (n = 10) to evaluate the usability of the Bezier surface interaction compared to a free deformation approach using the example of liver surgery planning. Moreover, we showed the prototype to an expert and conducted an interview to collect clinical feedback. The results show potential benefits of both interaction techniques that could be essential for virtual resection planning and training. The expert highlighted that combining both techniques could speed up the workflow and provide various options for planning.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{gulamhussene_needle_2023,

title = {Needle Tip Tracking During CT-guided Interventions using Fuzzy Segmentation},

author = {G Gulamhussene and A Das and J Spiegel and D Punzet and M Rak and C Hansen},

editor = {T Deserno and H Handels and A Maier and K Maier-Hein and C Palm and T Tolxdorff},

doi = {10.1007/978-3-658-41657-7_62},

isbn = {978-3-658-41657-7},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

booktitle = {Bildverarbeitung für die Medizin 2023},

pages = {285–291},

publisher = {Springer Fachmedien},

address = {Wiesbaden},

abstract = {CT-guided interventions are standard practice for radiologists to treat lesions in various parts of the human body. In this context, accurate tracking of instruments is of paramount importance for the safety of the procedure and helps radiologists avoid unintended damage to adjacent organs. In this work, a novel method for the estimation of 3D needle tip coordinates in a CT volume using only two 2D projections in an interventional setting is proposed. The method applies a deep learning model for the fuzzy segmentation of the region containing the tip on 2D projections and automatically extracts the position of the tip. A simple UNet achieves a Dice score of 0.9906 for the fuzzy segmentation and an average euclidean distance of 2.96 mm for the needle tip regression task.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{gulamhussene_deep_2023,

title = {Deep Learning-based Marker-less Pose Estimation of Interventional Tools using Surrogate Keypoints},

author = {G Gulamhussene and J Spiegel and A Das and M Rak and C Hansen},

editor = {T Deserno and H Handels and A Maier and K Maier-Hein and C Palm and T Tolxdorff},

doi = {10.1007/978-3-658-41657-7_63},

isbn = {978-3-658-41657-7},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

booktitle = {Bildverarbeitung für die Medizin 2023},

pages = {292–298},

publisher = {Springer Fachmedien},

address = {Wiesbaden},

abstract = {Estimating the position of an intervention needle is an important ability in computer-assisted interventions. Currently, such pose estimations rely either on radiation-intensive CT imaging or need additional optical markers which add overhead to the clinical workflow. We propose a novel deep-learning-based technique for pose estimation of interventional tools which relies on detecting visible features on the tool itself without additional markers.We also propose a novel and fast pipeline for creating vast amounts of robustly labeled and markerless ground truth data for training such neural networks. Initial evaluations suggest that with needle base and needle tip localization errors of about 1 and 4 cm, Our approach can yield a search corridor that can be used to find the needle in a low-dose CT image, reducing radiation exposure.},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}

@inproceedings{gulamhussene_using_2023,

title = {Using Training Samples as Transitive Information Bridges in Predicted 4D MRI},

author = {G Gulamhussene and O Bashkanov and J Omari and M Pech and C Hansen and M Rak},

editor = {Z Xue and S Antani and G Zamzmi and F Yang and S Rajaraman and S Huang and M Linguraru and Z Liang},

doi = {10.1007/978-3-031-44917-8_23},

isbn = {978-3-031-44917-8},

year  = {2023},

date = {2023-01-01},

urldate = {2023-01-01},

booktitle = {Medical Image Learning with Limited and Noisy Data},

pages = {237–245},

publisher = {Springer Nature Switzerland},

address = {Cham},

abstract = {The lack of real-time techniques for monitoring respiratory motion impairs the development of guidance systems for image-guided interventions. Recent works show that U-Net based real-time 4D MRI prediction methods are promising, but prone to bad image quality when small training data sets and inputs with multiple MR contrast are used. To overcome this problem, we propose a more efficient use of the spare training data and re-utilize 2D training samples as a secondary input for construction of transitive information bridges between the navigator slice primary input and the data slice prediction. We thus remove the need for a separate 3D breath-hold MRI with different MR contrast as the secondary input. Results show that our novel construction leads to improved prediction quality with very sparse training data, with a significant decrease in root mean squared error (RMSE) from 0.3 to 0.27 (p$$<2.2eˆ-16$$<2.2e-16},

keywords = {},

pubstate = {published},

tppubtype = {inproceedings}

}