Unsupervised domain adaptation for vertebrae detection and identification in 3D CT volumes using a domain sanity loss

A variety of medical computer vision applications analyze 2D slices of computed tomography (CT) scans, whereas axial slices from the body trunk region are usually identified based on their relative position to the spine. A limitation of such systems is that either the correct slices must be extracted manually or labels of the vertebrae are required for each CT scan to develop an automated extraction system. In this paper, we propose an unsupervised domain adaptation (UDA) approach for vertebrae detection and identification based on a novel Domain Sanity Loss (DSL) function. With UDA the model’s knowledge learned on a publicly available (source) data set can be transferred to the target domain without using target labels, where the target domain is defined by the specific setup (CT modality, study protocols, applied pre- and processing) at the point of use (e.g., a specific clinic with its specific CT study protocols). With our approach, a model is trained on the source and target data set in parallel. The model optimizes a supervised loss for labeled samples from the source domain and the DSL loss function based on domain-specific “sanity checks” for samples from the unlabeled target domain. Without using labels from the target domain, we are able to identify vertebra centroids with an accuracy of 72.8%. By adding only ten target labels during training the accuracy increases to 89.2%, which is on par with the current state-of-the-art for full supervised learning, while using about 20 times less labels. Thus, our model can be used to extract 2D slices from 3D CT scans on arbitrary data sets fully automatically without requiring an extensive labeling effort, contributing to the clinical adoption of medical imaging by hospitals

Performance of the New FlashCam-based Camera in the 28\,m Telescope of H.E.S.S

In October 2019, the central 28 m telescope of the H.E.S.S. experiment has been upgraded with a new camera. The camera is based on the FlashCam design which has been developed in view of a possible future implementation in the Medium-Sized Telescopes of the Cherenkov Telescope Array (CTA), with emphasis on cost and performance optimization and on reliability. The fully digital design of the trigger and readout system makes it possible to operate the camera at high event rates and to precisely adjust and understand the trigger system. The novel design of the front-end electronics achieves a dynamic range of over 3,000 photoelectrons with only one electronics readout circuit per pixel. Here we report on the performance parameters of the camera obtained during the first year of operation in the field, including operational stability and optimization of calibration algorithms.Comment: Proceedings of the 37th International Cosmic Ray Conference (ICRC 2021

Remote Experimentation Mashup

eLogbook is a new Web 2.0 social software framework developed in the Swiss Federal Institute of Technology in Lausanne (EPFL, Switzerland) to provide collaborative Web services in an open academic environment for higher education. Several cross platform Web-based technologies compose the internal architecture of this tool which is intended to online learning communities and community of practices with high social interaction demand. In this paper, we describe the necessary requirements to integrate external Web-based applications for remote experimentation into eLogbook. The integration of a virtual and remote control laboratory from the National University for Distance Education (UNED, Spain) is presented as a case of study

Collecting Experience Data from Remotely Hosted Learning Applications

The ability to integrate multiple learning applications from different organizations allows sharing resources and reducing costs in the deployment of learning systems. In this sense, Learning Tools Interoperability (LTI) is the main current leading technology for integrating learning applications with platforms like Learning Management Systems (LMS). On the other hand, the integration of learning applications also benefits from data collection, which allows learning systems to implement Learning Analytics (LA) processes. Tin Can API is a specification for learning technology that makes this possible. Both learning technologies, LTI and Tin Can API, are supported by nowadays LMS, either natively or through plugins. However, there is no seamless integration between these two technologies in order to provide learning systems with experience data from remotely hosted learning applications. Our proposal defines a learning system architecture ready to apply advanced LA techniques on experience data collected from remotely hosted learning applications through a seamless integration between LTI and Tin Can API. In order to validate our proposal, we have implemented a LRS proxy plug-in in Moodle that stores learning records in a SCORM Cloud LRS service, and a basic online lab based on Easy JavaScript Simulation (EjsS). Moreover, we have tested our implementation using resources located in three European universities

Dosimetry of selective retina therapy using optical coherence tomography: first results from the CENTAURUS study

Purpose : Assessment of the SPECTRALIS CENTAURUS device for real-time feedback-controlled dosimetry (RFD) of selective retina therapy (SRT). Evaluation of optical coherence tomography (OCT) data for future real-time dosimetry applications. Methods : A test pattern (single pulse) for damage threshold determination as well as a specified laser treatment pattern for RFD simulation (ramped up pulse sequence, maximal 30 pulses, 100 Hz) were applied in 3 patients with diabetic retinopathy using the SPECTRALIS CENTAURUS device (HuCE-optoLab, BFH-TI, CH). This device consists of a modified imaging platform (SPECTRALIS HRA+OCT, Heidelberg Engineering, DE) extended with a prototype laser (Meridian Medical; wavelength: 532 nm; peak power: 30 W) for SRT. Laser pulses of 8 µs duration with a maximum pulse energy of 170 µJ were used. OCT M-scan data recorded during treatment was analyzed post-treatment to investigate OCT-RFD. The patterns were evaluated binary for retinal pigment epithelium (RPE) damage based on fluorescence angiography (FA), overtreatment based on color fundus photography (CFP), as well as OCT M-scans fringe washouts (visually / dedicated algorithm). Probit analysis was used to calculate the ED-values (median-effective dose), the therapeutic window (TW = ED50-CFP / ED50-FA), and the safety range (SR = ED16-CFP / ED84-FA) for SRT. Results : Probit analysis for the test pattern shows an RPE damage threshold of 57 µJ (ED50-FA) and a threshold towards overtreatment of 95 µJ (ED50-CFP). Furthermore, a TW of 1.7 and a SR of 1.2 for SRT was found. For all lesions, OCT M-scan feedback (detectable fringe washouts) is guaranteed with 50% probability from 47 µJ on (visual evaluation), respectively 53 µJ (algorithm). At the lower SR limit (ED84-FA = 75 µJ), visually evaluated dosimetry could provide feedback with 98% and the algorithm with 95% probability. At the upper SR limit (ED16-CFP = 92 µJ), both methods could provide feedback with 99% probability. A statistical evaluation of the RFD simulation pattern shows that over all a sensitivity of 83% and a specificity of 93% was achieved for the dosimetry algorithm. Conclusions : OCT-RFD of SRT using the SPECTRALIS CENTAURUS device is feasible in patients with diabetic retinopathy, indicating that controlled retinal treatment is possible. Applying the algorithm in real-time would have reduced the applied energy dose for certain lesions by 30%

High resolution optical coherence tomography reveals details of regeneration after selective retina therapy

Purpose : To investigate the course of retinal regeneration after selective retina therapy (SRT) using high-resolution spectral-domain optical coherence tomography (High-Res-OCT). Methods : Imaging data origin from the CENTAURUS study. SRT was performed in patients with diabetic retinopathy using the SPECTRALIS CENTAURUS device (HuCE-optoLab, BFH-TI, Switzerland). SRT laser lesions were observed over a follow-up period of 6 months using High-Res-OCT (Heidelberg Engineering, Germany). High-Res-OCT enables imaging with increased axial resolution of up to 3 µm due to increased bandwidth of 130 nm (central wavelength: 840 nm) compared to conventional spectral-domain OCT devices (bandwidth: 40 nm, axial resolution 7 µm). Results : Up to 90 laser lesions with different laser pulse energy in the retina of two subjects were analyzed over a follow-up period of six months. Laser lesions, especially those with higher laser pulse energy lead to an initial hyperreflectivity in the outer retinal layers, which disappeared within the first week. After one week, a local proliferation and hyperreflectivity on the level of the retinal pigment epithelium (RPE) was observed, which normalized over the course of six months. At the final visit, no remaining retinal changes after SRT laser were detectable using High-Res-OCT. Conclusions : The increased axial resolution makes High-Res-OCT a great imaging tool for detection of subtle retinal changes after SRT, and for follow-up over time. SRT lesions especially lead to focal proliferation in the level of the RPE with regeneration over time without observation of permanent scar formation or induction of neovascularization

Biologic principles of minced cartilage implantation: a narrative review

Cartilage tissue has a very limited ability to regenerate. Symptomatic cartilage lesions are currently treated by various cartilage repair techniques. Multiple treatment techniques have been proposed in the last 30 years. Nevertheless, no single technique is accepted as a gold standard. Minced cartilage implantation is a newer technique that has garnered increasing attention. This procedure is attractive because it is autologous, can be performed in a single surgery, and is therefore given it is cost-effective. This narrative review provides an overview of the biological potential of current cartilage regenerative repair techniques with a focus on the translational evidence of minced cartilage implantation