Nicholas E Protonotarios

Dr. Nicholas E Protonotarios

Mathematics Research Center, Academy of Athens, Athens, Attikí, Greece
orcid

Research Focus & Metrics

Academic Career Length

11Years (2016-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
28 January 2024 in Computers in Biology and Medicine
Verified
Journal Article
Open access
SMSotirios Messinis
Sotirios Messinis
NTNikos Temenos
Nikos Temenos
Nicholas E ProtonotariosNicholas E Protonotarios
Nicholas E Protonotarios
IRIoannis Rallis
Ioannis Rallis
Dimitris K KalogerasDimitris K Kalogeras
Dimitris K Kalogeras
NDNikolaos Doulamis
Nikolaos Doulamis
Over the past five years, interest in the literature regarding the security of the Internet of Medical Things (IoMT) has increased. Due to the enhanced interconnectedness of IoMT devices, their susceptibility to cyber-attacks has proportionally escalated. Motivated by the promising potential of AI-related technologies to improve certain cybersecurity measures, we present a comprehensive review of this emerging field. In this review, we attempt to bridge the corresponding literature gap regarding modern cybersecurity technologies that deploy AI techniques to improve their performance and compensate for security and privacy vulnerabilities. In this direction, we have systematically gathered and classified the extensive research on this topic. Our findings highlight the fact that the integration of machine learning (ML) and deep learning (DL) techniques improves both the performance of cybersecurity measures and their speed, reliability, and effectiveness. This may be proven to be useful for improving the security and privacy of IoMT devices. Furthermore, by considering the numerous advantages of AI technologies as opposed to their core cybersecurity counterparts, including blockchain, anomaly detection, homomorphic encryption, differential privacy, federated learning, and so on, we provide a structured overview of the current scientific trends. We conclude with considerations for future research, emphasizing the promising potential of AI-driven cybersecurity in the IoMT landscape, especially in patient data protection and in data-driven healthcare.

18 February 2022 in Biomedical Physics & Engineering Express
Verified
Journal Article
Closed access
Nicholas E ProtonotariosNicholas E Protonotarios
Nicholas E Protonotarios
IKIason Katsamenis
Iason Katsamenis
SSStavros Sykiotis
Stavros Sykiotis
NDNikolaos Dikaios
Nikolaos Dikaios
George KastisGeorge Kastis
George Kastis
ADAnastasios Doulamis
Anastasios Doulamis
Over the past few years, positron emission tomography/computed tomography (PET/CT) imaging for computer-aided diagnosis has received increasing attention. Supervised deep learning architectures are usually employed for the detection of abnormalities, with anatomical localization, especially in the case of CT scans. However, the main limitations of the supervised learning paradigm include (i) large amounts of data required for model training, and (ii) the assumption of fixed network weights upon training completion, implying that the performance of the model cannot be further improved after training. In order to overcome these limitations, we apply a few-shot learning (FSL) scheme. Contrary to traditional deep learning practices, in FSL the model is provided with less data during training. The model then utilizes end-user feedback after training to constantly improve its performance. We integrate FSL in a U-Net architecture for lung cancer lesion segmentation on PET/CT scans, allowing for dynamic model weight fine-tuning and resulting in an online supervised learning scheme. Constant online readjustments of the model weights according to the users’ feedback, increase the detection and classification accuracy, especially in cases where low detection performance is encountered. Our proposed method is validated on the Lung-PET-CT-DX TCIA database. PET/CT scans from 87 patients were included in the dataset and were acquired 60 minutes after intravenous 18 F-FDG injection. Experimental results indicate the superiority of our approach compared to other state-of-the-art methods.

28 November 2018 in Journal of The Royal Society Interface
Verified
Journal Article
Closed access
PDF file
Nicholas E ProtonotariosNicholas E Protonotarios
Nicholas E Protonotarios
AFAthanassios S. Fokas
Athanassios S. Fokas
KKKostas Kostarelos
Kostas Kostarelos
George KastisGeorge Kastis
George Kastis
We present the attenuated spline reconstruction technique (aSRT) which provides an innovative algorithm for single photon emission computed tomography (SPECT) image reconstruction. aSRT is based on an analytic formula of the inverse attenuated Radon transform. It involves the computation of the Hilbert transforms of the linear attenuation function and of two sinusoidal functions of the so-called attenuated sinogram . These computations are achieved by employing the attenuation information provided by computed tomography (CT) scans and by utilizing custom-made cubic spline interpolation. The purpose of this work is: (i) to present the mathematics of aSRT, (ii) to reconstruct simulated and real SPECT/CT data using aSRT and (iii) to evaluate aSRT by comparing it to filtered backprojection (FBP) and to ordered subsets expectation minimization (OSEM) reconstruction algorithms. Simulation studies were performed by using an image quality phantom and an appropriate attenuation map. Reconstructed images were generated for 45, 90 and 180 views over 360 degrees with 20 realizations and involved Poisson noise of three different levels (NL), namely 100% (NL1), 50% (NL2) and 10% (NL3) of the total counts, respectively. Moreover, real attenuated SPECT sinograms were reconstructed from a real study of a Jaszczak phantom, as well as from a real clinical myocardial SPECT/CT study. Comparisons between aSRT, FBP and OSEM reconstructions were performed using contrast, bias and image roughness. The results suggest that aSRT can efficiently produce accurate attenuation-corrected reconstructions for simulated and real phantoms, as well as for clinical data. In particular, in the case of the clinical myocardial study, aSRT produced reconstructions with higher cold contrast than both FBP and OSEM. aSRT, by incorporating the attenuation correction within itself, may provide an improved alternative to FBP. This is particularly promising for ‘cold’ regions as those occurring in myocardial ischaemia.

8 August 2024 in Sensors
Verified
Journal Article
Open access
PDF file
SMSotirios Messinis
Sotirios Messinis
Nicholas E ProtonotariosNicholas E Protonotarios
Nicholas E Protonotarios
NDNikolaos Doulamis
Nikolaos Doulamis
Federated learning (FL) has emerged as a pivotal paradigm for training machine learning models across decentralized devices while maintaining data privacy. In the healthcare domain, FL enables collaborative training among diverse medical devices and institutions, enhancing model robustness and generalizability without compromising patient privacy. In this paper, we propose DPS-GAT, a novel approach integrating graph attention networks (GATs) with differentially private client selection and resource allocation strategies in FL. Our methodology addresses the challenges of data heterogeneity and limited communication resources inherent in medical applications. By employing graph neural networks (GNNs), we effectively capture the relational structures among clients, optimizing the selection process and ensuring efficient resource distribution. Differential privacy mechanisms are incorporated, to safeguard sensitive information throughout the training process. Our extensive experiments, based on the Regensburg pediatric appendicitis open dataset, demonstrated the superiority of our approach, in terms of model accuracy, privacy preservation, and resource efficiency, compared to traditional FL methods. The ability of DPS-GAT to maintain a high and stable number of client selections across various rounds and differential privacy budgets has significant practical implications, indicating that FL systems can achieve strong privacy guarantees without compromising client engagement and model performance. This balance is essential for real-world applications where both privacy and performance are paramount. This study suggests a promising direction for more secure and efficient FL medical applications, which could improve patient care through enhanced predictive models and collaborative data utilization.

30 October 2024 in Cancers
Verified
Journal Article
Open access
PDF file
AGAb Majeed Ganai
Ab Majeed Ganai
EVEirinaios I. Vrettos
Eirinaios I. Vrettos
SKStavroula Kyrkou
Stavroula Kyrkou
VZVASILIKI ZOI
VASILIKI ZOI
TPTabasum Khan Pathan
Tabasum Khan Pathan
ATAndreas Tzakos
Andreas Tzakos
Kinase inhibitors are potent therapeutic agents in cancer treatment, but their effectiveness is frequently restricted by the inability to image the tumor microenvironment. To address this constraint, kinase inhibitor–fluorophore conjugates have emerged as promising theranostic agents, allowing for simultaneous cancer diagnosis and treatment. These conjugates are gaining attention for their ability to visualize malignant tissues and concurrently enhance therapeutic interventions. This review explores the design principles governing the development of multimodal inhibitors, highlighting their potential as platforms for kinase tracking and inhibition via bioimaging. The structural aspects of constructing such theranostic agents are critically analyzed. This work could shed light on this intriguing field and provide adequate impetus for developing novel theranostic compounds based on small molecule inhibitors and fluorophores.

26 June 2024
Verified
Conference Paper
Open access
STSteve Taylor
Steve Taylor
Martin Gilje JaatunMartin Gilje Jaatun
Martin Gilje Jaatun
KBKarin Bernsmed
Karin Bernsmed
CAChristos Androutsos
Christos Androutsos
DFDietmar Frey
Dietmar Frey
Konstantinos KatzisKonstantinos Katzis
Konstantinos Katzis
MDCG 2019-16 is intended to assist practitioners in compliance with the Medical Device Regulation and the In-Vitro Device Regulation. This paper presents a gap analysis of MDCG 2019-16, identifying key gaps and proposing a robust set of recommendations to enhance the IoMT regulatory framework. This work has been undertaken by a selection of current (2023-2025) projects, all funded under the Horizon Europe call “Enhancing cybersecurity of connected medical devices”: HORIZON-HLTH-2022-IND-13-01, and this paper summarises observations and recommendations from across these projects. There is considerable consensus across the projects in many recommendation themes, notably; linking cybersecurity with patient safety and privacy; keeping the guidelines current; and usage recipes for the guidelines. The paper also suggests toolkit solutions to address some of the recommendations.