Quantitatively assessing the level of readiness of medical technology improves its chance of successfully transfer from research to industry but remains a challenge. As many innovative medical devices are associated with or incorporate software, this article presents a methodology for evaluating the software maturity of a "Software-driven Medical Technology" (SdMT) during the research phase. A technological maturity model is developed by methodologically extracting relevant terms from the ISO/IEC 62304 standard, the main industry standard for medical device software, and results in a list of required software engineering artifacts. This list and the relative weight of the artifacts are used to establish a software maturity score for SdMT and the corresponding assessment questionnaire. The consistency of the model is demonstrated by analyzing the obtained score system relatively with the standard. The maturity score of a SdMT can be assessed during the research phase and depends on the number and importance of the artifacts already present at the time of evaluation.Clinical relevance— The proposed quantitative maturity score can help the medical technology innovation actors (clinicians, researchers and industrials) to better identify, improve and fasten the readiness of technology for clinical investigation and technology transfer.

Multi-camera systems were recently introduced into laparoscopy to increase the narrow field of view of the surgeon. The video streams are stitched together to create a panorama that is easier for the surgeon to comprehend. Multi-camera prototypes for laparoscopy use quite basic algorithms and have only been evaluated on simple laparoscopic scenarios. The more recent state-of-the-art algorithms, mainly designed for the smartphone industry, have not yet been evaluated in laparoscopic conditions. We developed a simulated environment to generate a dataset of multi-view images displaying a wide range of laparoscopic situations, which is adaptable to any multi-camera system. We evaluated classical and state-of-the-art image stitching techniques used in non-medical applications on this dataset, including one unsupervised deep learning approach. We show that classical techniques that use global homography fail to provide a clinically satisfactory rendering and that even the most recent techniques, despite providing high quality panorama images in non-medical situations, may suffer from poor alignment or severe distortions in simulated laparoscopic scenarios. We highlight the main advantages and flaws of each algorithm within a laparoscopic context, identify the main remaining challenges that are specific to laparoscopy, and propose methods to improve these approaches. We provide public access to the simulated environment and dataset.

Introduction. - Simulation-based training has proven to be a promising option allowing for initial and continuous training while limiting the impact of the learning curve on the patient. The Biopsym simulator was developed as a complete teaching environment for the prostate biopsy procedure. This paper presents the results of an external validation of this simulator, involving urology residents recruited during a regional teaching seminar. Methods. - Residents from 4 academic urology departments of the French Auvergne Rhone-Alpes region, who did not take part in the previous simulator validation studies, were enrolled. After a short presentation and standardized initiation session, residents carried out a simulated systematic 12-core biopsy procedure and were asked to fill in a questionnaire collecting their expectations and evaluation of the Biopsym simulator. The number of biopsies reaching each targeted sector, the total score provided by the simulator and the duration of the procedure were recorded. Results. - Twenty-three residents were recruited. The overall added value (/100) for learning was rated at a median of 100 (interquartile range 83-100), overall realism of the biopsy procedure at 80 (65-89). The median percentage of biopsies reaching the targeted sector was 66.7% (62-75). The median score provided by the simulator was 50% (37-60). For both, the difference between residents with or without prior biopsy experience was not statistically significant. The median duration of the simulated biopsy procedure was 4:58 (minutes: seconds) (3:49-6:00). Resident with prior experience required less time to complete the biopsy procedure 3:53 (3:39-4:56) vs. 5:10 (4:59-7:10), P= 0.01. Conclusion. - This external validation study confirms a high acceptance of the simulator by the target audience. To our knowledge, the Biopsym simulator is the only prostate biopsy simulator that demonstrated such validity as evaluated by clinicians, outside the center involved in its early development. (C) 2021 Elsevier Masson SAS. All rights reserved.

OBJECTIVES: To evaluate the ability of students to reproduce the skills acquired on a prostate biopsy simulator in a real-life situation. DESIGN: A prospective randomized controlled study was conducted. Medical students with no experience of prostate biopsy were randomized between arm A "conventional training" and arm B "simulator-enhanced training. "The training was performed for both groups on the simulator. The students in arm B were provided with visual and numerical feedback. The transfer of skills was assessed by recording the position of the 12 biopsies performed by each student on an unembalmed human cadaver using a 3D ultrasound mapping device. SETTING: The study was conducted in an academic urology department and the cadaver experiments in the adjoining anatomy laboratory. RESULTS: Twenty-four students were included, and 22 completed the study. The median score obtained on the simulator at the end of the training was 57% (53-61) for arm A and 66% (59-71) for arm B. The median score obtained on the cadaver by students trained with the simulator was 75% (60-80), statistically superior to the score obtained by students trained conventionally of 45% (30-60), p < 0.0001. Themedian score obtained by all students when performing biopsies in a real-life situation was 63% (50-80) versus 60% (56-70) for their last training on the simulator. CONCLUSION: These results support the transfer of skills acquired on the simulator, and the superiority of a training curriculum integrating simulation, and performance feedback. (C) 2020 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Objectives: The Biopsym simulator, a virtual-reality simulator for prostate biopsies, was designed to offer enhanced teaching of the biopsy procedure. The objectives of the present article are to describe the new version of the simulator and report the results of a new validation study. Material and methods: A prospective validation study was conducted between January and March 2017. The new version of the simulator, with improved physical realism, ultrasound image deformation, and a new scoring system, was evaluated by novice and confirmed users. Results: Twenty-one users evaluated the simulator, including ten novices and 11 confirmed users. The overall realism of the biopsy procedure was rated at 7.7/10 (IQR 5.7-9). The differences between the rates given by confirmed users and novices were not statistically significant. The median overall score obtained for the performance of 12 systematic ultrasound-guided biopsies was 43% (IQR 33-55). The median score obtained by confirmed users was 54% (IQR 46-62), and the median score obtained by novices was 31% (IQR 20-35). The difference between the scores was statistically significant (p = 0.005). Conclusions: This study allowed us to gather evidence towards the validation, and particularly towards the construct validation of the new version of the Biopsym simulator.

The aim of this paper is to describe a 3D-2D ultrasound feature-based registration method for navigated prostate biopsy and its first results obtained on patient data. A system combining a low-cost tracking system and a 3D-2D registration algorithm was designed. The proposed 3D-2D registration method combines geometric and image-based distances. After extracting features from ultrasound images, 3D and 2D features within a defined distance are matched using an intensity-based function. The results are encouraging and show acceptable errors with simulated transforms applied on ultrasound volumes from real patients.

Le simulateur biopsym (Fig. 1) est un environnement d’apprentissage de la biopsie prostatique permettant la formation initiale ou le perfectionnement du geste (biopsies randomisées, biopsies ciblées, fusion cognitive échographie-IRM). Les étapes de validation initiales ont permis de valider l’apparence, le contenu, la fiabilité et le construit. L’objectif de cette étude était de valider le transfert des compétences acquises sur le simulateur. Vingt-deux étudiants (externes) ont été inclus de manière prospective et randomisés en 2 groupes : apprentissage classique (groupe 1) versus apprentissage avancé avec retour sur performance (groupe 2). Les étudiants ont ensuite tous été formés sur le simulateur à la réalisation d’une série de 12 biopsies prostatiques randomisées, le groupe 2 disposant en plus d’un retour sur ses performances. La validation du transfert a été réalisée sur sujet anatomique en enregistrant la position des biopsies à l’aide de la plateforme koelis (Fig. 2). Un score a alors été calculé selon la répartition des biopsies par rapport à une grille divisant la prostate en 12 secteurs. Les scores médians (Q1–Q3) obtenus par l’ensemble de la cohorte sur simulateur (fin évaluation), puis sur sujet anatomique étaient de 57 % (51–68) et 63 % (50–75), respectivement. Les scores obtenus lors de la première et dernière série de 12 biopsies sur simulateur étaient respectivement de 45 % (29–59) et 60 % (52–66) pour le groupe 1 et 52 % (49–52) et 57 % (56–72) pour le groupe 2. Les étudiants du groupe 2 ont obtenu sur sujet anatomique un score médian de 67 % (58–83), significativement supérieur au score médian de 50 % (38–67) des étudiants du groupe 1 (p = 0,04) (Fig. 3). À l’heure où la HAS recommande de ne jamais réaliser un geste pour la première fois sur le patient, le simulateur de biopsies prostatiques biopsym a montré sa capacité à former des étudiants qui sont ensuite capables de reproduire leur performance en situation réelle.

Le simulateur Biopsym est un environnement d’apprentissage de la biopsie prostatique permettant la formation initiale ou le perfectionnement du geste (biopsies randomisées, biopsies ciblées, fusion cognitive échographie-IRM). Une première étude de validation avait été réalisée ne permettant pas de valider le construit (discrimination confirmée/novices) du fait d’un manque de réalisme perturbant les experts. L’objectif de cette étude était de valider cette étape à partir d’une nouvelle version plus réaliste du simulateur. La première version du simulateur consistait en un ordinateur relié à un bras à retour d’effort muni d’un stylet manié en guise de sonde d’échographie. Les amplitudes de mouvement dans l’espace (translations latérales) n’étaient pas limitées. Une sonde d’échographie a été créée en impression 3D et connectée au bras, introduite à travers un anus en silicone (Fig. 1). Après un module d’introduction permettant de découvrir le fonctionnement du simulateur et la réalisation d’une check-list pré-procédure, chaque utilisateur a pu réaliser 12 biopsies randomisées sur simulateur et obtenir un score sur 100 % exprimant la qualité de répartition des biopsies au sein du volume prostatique. Les scores obtenus par les novices et les experts ont été comparés. Onze utilisateurs confirmés (urologues seniors ou internes d’urologie fin de cursus) et 10 novices (étudiants en médecine) ont testé la nouvelle version du simulateur. Le score médian obtenu par les novices était de 31 % (20–35), celui des utilisateurs confirmés de 51 % (46–57). Cette différence était statistiquement significative (p = 0,0053, Fig. 2). La durée médiane pour réaliser l’exercice par les utilisateurs confirmés était de 3 minutes et 30 secondes (3 : 11–4 : 12) versus 5 minutes et 25 secondes (4 : 49–6 : 53) pour les novices (p < 0,001). L’évaluation du réalisme global de la procédure de biopsies par les utilisateurs confirmés sur une échelle de 1 à 10 était évaluée à 7/10 (6–9). Cette nouvelle version du simulateur a pu être validée au niveau du construit (capacité à discriminer les utilisateurs confirmés et les novices) grâce à une amélioration de son réalisme. La dernière étape de validation restante consistera à valider le transfert des compétences acquises lors de la réalisation de biopsies en situation réelle.

Prostate volume changes due to edema occurrence during transperineal permanent brachytherapy should be taken under consideration to ensure optimal dose delivery. Available edema models, based on prostate volume observations, face several limitations. Therefore, patient-specific models need to be developed to accurately account for the impact of edema. In this study we present a biomechanical model developed to reproduce edema resolution patterns documented in the literature. Using the biphasic mixture theory and finite element analysis, the proposed model takes into consideration the mechanical properties of the pubic area tissues in the evolution of prostate edema. The model's computed deformations are incorporated in a Monte Carlo simulation to investigate their effect on post-operative dosimetry. The comparison of Day1 and Day30 dosimetry results demonstrates the capability of the proposed model for patient-specific dosimetry improvements, considering the edema dynamics. The proposed model shows excellent ability to reproduce previously described edema resolution patterns and was validated based on previous findings. According to our results, for a prostate volume increase of 10-20% the Day30 urethra D10 dose metric is higher by 4.2%-10.5% compared to the Day1 value. The introduction of the edema dynamics in Day30 dosimetry shows a significant global dose overestimation identified on the conventional static Day30 dosimetry. In conclusion, the proposed edema biomechanical model can improve the treatment planning of transperineal permanent brachytherapy accounting for post-implant dose alterations during the planning procedure.

Classic Random Regression Forests(RRFs) used for multiorgan localization describe the random process of multivariate regression by storing the histograms of offset vectors along each bounding wall direction per leaf node. On the one hand, the RAM and storage requirements of classic RRFs may become exorbitantly high when such a RRF consists of many leaf nodes, but on the other hand, a large number of leaf nodes are required for better localization. We introduce Light Random Regression Forests (LRRFs) which eliminate the need to describe the random process by formulating the localization prediction based on the random variables that describe the random process. Consequently, LRRFs with the same localization capabilities require less RAM and storage space compared to classic RRFs. LRRF comprising 4 trees with 17 decision levels is approximately 9 times faster, takes 10 times less RAM, and uses 30 times less storage space compared to a similar classic RRF.

Morphogenesis is a general concept in biology including all the processes which generate tissue shapes and cellular organizations in a living organism. Many hybrid formalizations (i.e., with both discrete and continuous parts) have been proposed for modelling morphogenesis in embryonic or adult animals, like gastrulation. We propose first to study the ventral furrow invagination as the initial step of gastrulation, early stage of embryogenesis. We focus on the study of the connection between the apical constriction of the ventral cells and the initiation of the invagination. For that, we have created a 3D biomechanical model of the embryo of the Drosophila melanogaster based on the finite element method. Each cell is modelled by an elastic hexahedron contour and is firmly attached to its neighbouring cells. A uniform initial distribution of elastic and contractile forces is applied to cells along the model. Numerical simulations show that invagination starts at ventral curved extremities of the embryo and then propagates to the ventral medial layer. Then, this observation already made in some experiments can be attributed uniquely to the specific shape of the embryo and we provide mechanical evidence to support it. Results of the simulations of the "pill-shaped" geometry of the Drosophila melanogaster embryo are compared with those of a spherical geometry corresponding to the Xenopus lævis embryo. Eventually, we propose to study the influence of cell proliferation on the end of the process of invagination represented by the closure of the ventral furrow.

3D UltraSound (US) probes are used in clinical applications for their ease of use and ability to obtain intra-operative volumes. In surgical navigation applications a calibration step is needed to localize the probe in a general coordinate system. This paper presents a new hand-eye calibration method using directly the kinematic model of a robot and US volume registration data that does not require any 3D localizers. First results show a targeting error of 2.34 mm on an experimental setup using manual segmentation of five beads in ten US volumes.

The PROSBOT project aims to improve the clinical gesture of prostate biopsy sampling through a pedagogic simulator and a robotic assistance system. The objective of the simulator is to improve the learning curve of systematic and targeted prostate biopsy acquisition through realistic simulations of the gesture and a multitude of pedagogic modules. This paper reports the developed versions of the simulator and their evaluation. The robotic assistance system, called Apollo, is a co-manipulated robotic probe holder that aims at improving the clinical gesture through several functions, amongst which are: a) locking the probe in a target position, b) providing haptic feed-back to reduce gland deformation and c) gravity compensation. Two cadaver studies have shown that the device does not negatively impact or disturb the clinical gestures (transparency), but that gravity compensation improves the ergonomics of the gesture and that the locking function helps considerably at maintaining a stable position during puncture. A clinical study is currently ongoing with the objective to prove that biopsy accuracy can be improved with the robot, both for systematic and targeted sampling. Finally, the Apollo project is in an advanced stage of industrialization and will become commercially available. The possibilities for industrialization of the simulator are currently evaluated through a follow-up study.

Les méthodes actuelles d’apprentissage des biopsies prostatiques ont montré leurs limites, et de nouveaux besoins de formation apparaissent (biopsies ciblées, fusion d’images…). Nous avons mis au point un simulateur de biopsies prostatiques dont nous avons précédemment réalisé la validation, et développé un parcours pédagogique progressif dont nous présentons ici la première évaluation. Le simulateur consiste en un ordinateur portable relié à un dispositif haptique auquel est connecté un modèle de sonde d’échographie endorectale (Fig. 1). Il inclut une base de données cliniques (volumes échographiques 3D) et un environnement pédagogique. Le parcours pédagogique propose après la réalisation d’une évaluation initiale, une série d’exercices séquentiels adaptés aux besoins de l’étudiant. Ceux-ci sont de difficulté croissante (QCM, lecture d’image échographiques, mesure du volume prostatique, biopsies randomisées, biopsies ciblées) et peuvent être réalisés avec ou sans assistance (visualisation en temps réel du trajet de biopsie dans le volume prostatique). Une évaluation finale permet d’enregistrer les résultats de la formation. Au mois de juillet 2013, le parcours pédagogique a été évalué auprès de 4 étudiants en médecine n’ayant jamais assisté à une biopsie prostatique. Nous avons évalué la faisabilité de l’ensemble du parcours (durée, nombre de séances nécessaires) et le caractère pédagogique des exercices. La durée moyenne nécessaire à la réalisation du parcours était de 1h31 [1h22–1h42]. Les résultats de l’évaluation finale ont permis de mettre en évidence une amélioration du score obtenu (64 % vs 54 %) et du nombre de secteurs atteints (11 vs 7) pour 3 étudiants sur 4, et pour tous une amélioration de la durée d’une série de 12 biopsies (346 vs 708 s) (Fig. 2). Les conditions de réalisation du parcours (continu ou interrompu, durée de l’interruption) influençaient le résultat. Cette évaluation offre un retour positif sur une première version du parcours pédagogique qui a permis une amélioration des performances de la majorité des étudiants. Ses conditions de réalisation devront être standardisées pour les évaluations futures à plus grande échelle, et l’évaluation du transfert de compétences sur le patient.

Biomechanical modeling of the facial soft tissue behavior is needed in aesthetic or maxillo-facial surgeries where the simulation of the bone displacements cannot accurately predict the visible outcome on the patient's face. Because these tissues have different nature and elastic properties across the face, depending on their thickness, and their content in fat or muscle, individualizing their mechanical parameters could increase the simulation accuracy. Using a specifically designed aspiration device, the facial soft tissues deformation is measured at four different locations (cheek, cheekbone, forehead, and lower lip) on 16 young subjects. The stiffness is estimated from the deformations generated by a set of negative pressures using an inverse analysis based on a Neo Hookean model. The initial Young's modulus of the cheek, cheekbone, forehead, and lower lip are respectively estimated to be 31.0 kPa ± 4.6, 34.9 kPa ± 6.6, 17.3 kPa ± 4.1, and 33.7 kPa ± 7.3. Significant intra-subject differences in tissue stiffness are highlighted by these estimations. They also show important inter-subject variability for some locations even when mean stiffness values show no statistical difference. This study stresses the importance of using a measurement device capable of evaluating the patient specific tissue stiffness during an intervention.

Realistic medical procedure simulators improve the learning curve of the clinicians if they can reproduce real conditions and use. This paper describes the improvement of a transrectal ultrasound guided prostate biopsy simulator by adding the simulation of real-time prostate movements and deformations. A discrete bio-mechanical model is used to modify a 3D texture of an ultrasound image volume in order to quickly simulate the actual displacements and deformations. This paper describes this model and presents how the mesh deformation is used to induce the UltraSound volume deformation. The validation of the method is based on both a quantitative and a qualitative assessment. Experimental images acquired on a phantom are compared using mutual information metrics to the resulting generated images. This comparison shows that the proposed method offers realistic deformed 3D ultrasound images at interactive time. The method was successfully integrated to improve the transrectal ultrasound simulator.

BACKGROUND AND PURPOSE:A virtual-reality learning environment dedicated to prostate biopsies was designed to overcome the limitations of current classical teaching methods. The aim of this study was to validate reliability, face, content, and construct of the simulator.MATERIALS AND METHODS:The simulator is composed of (a) a laptop computer, (b) a haptic device with a stylus that mimics the ultrasound probe, (c) a clinical case database including three-dimensional (3D) ultrasound volumes and patient data, and (d) a learning environment with a set of progressive exercises including a randomized 12-core biopsy procedure. Both visual (3D biopsy mapping) and numerical (score) feedback are given to the user. The simulator evaluation was conducted in an academic urology department on 7 experts and 14 novices who each performed a virtual biopsy procedure and completed a face and content validity questionnaire.RESULTS:The overall realism of the biopsy procedure was rated at a median of 9/10 by nonexperts (7.1-9.8). Experts rated the usefulness of the simulator for the initial training of urologists at 8.2/10 (7.9-8.3), but reported the range of motion and force feedback as significantly less realistic than novices (P=0.01 and 0.03, respectively). Pearson r correlation coefficient between correctly placed biopsies on the right and left side of the prostate for each user was 0.79 (P<0.001). The 7 experts had a median score of 64% (59%-73%), and the 14 novices a median score of 52% (43%-67%), without reaching statistical significance (P=0.19).CONCLUSION:The newly designed virtual-reality learning environment proved its versatility and its reliability, face, and content were validated. Demonstrating the construct validity will necessitate improvements to the realism and scoring system used.

The biomechanical model presented in this paper offers precise dynamic simulation of the fetal head molding in a reasonable computational time making it suitable for use with haptic training simulators. Nevertheless, it can be improved by considering anisotropic material for the cranial bones. In future work, we plan to use our model with more complex scenarios involving the fetal head such as forceps and vacuum delivery.

The recent availability of navigation systems for mapping and targeting of transrectal ultrasound (TRUSS) guided prostate biopsies revealed new opportunities in training the clinician. This paper describes a simulator for TRUSS guided prostate biopsy that offers similar information, enhanced by a complete learning environment. Various exercises have been developed in accordance with a didactical study identifying the training needs. A dedicated clinical case database fed by a prostate navigation system provides a large patient prostate image database that covers the main situations encountered during clinical practice. A haptic device is used to enable complete biopsy procedures or practice specific tasks. This paper also presents work in progress of the evaluation of such a simulator.