The Accuracy and Effectiveness of Automatic Pedicle Screw Trajectory Planning Based on CT Values: An in Vitro Osteoporosis Model Study.

BackgroundPedicle screw placement in patients with osteoporosis is a serious clinical challenge. The bone mineral density (BMD) of the screw trajectory has been positively correlated with the screw pull-out force, while the CT value has been linearly correlated with the BMD. The purpose of this study was to establish an in vitro osteoporosis model and verify the accuracy and effectiveness of automated pedicle screw planning software based on CT values in this model.MethodsTen vertebrae (L1-L5) of normal adult pigs were randomly divided into a decalcification group and a control group. In the decalcification group, the vertebral bodies were decalcified with Ethylenediaminetetraacetic acid (EDTA) to construct an in vitro osteoporosis model. In the decalcification group, automatic planning (AP) and conventional manual planning (MP) were used to plan the pedicle screw trajectory on the left and right sides of the pedicle, respectively, and MP was used on both sides of the control group. CT values of trajectories obtained by the two methods were measured and compared. Then, 3D-printed guide plates were designed to assist pedicle screw placement. A biomechanical instrument was used to measure the pull-out force of the trajectory obtained by the two methods.ResultsAfter decalcification, the T' value of the vertebral body decreased from -0.03 ± 1.03 to -3.03 ± 0.29 (P <0.05). In the decalcification group, the MP trajectory CT value was 2167.28 ± 65.62 Hu, the AP trajectory CT value was 2723.96 ± 165.83 Hu, and the MP trajectory CT value in the control group was 2242.94 ± 25.80 Hu (P<0.05). In the decalcified vertebrae, the screw pull-out force of the MP group was 48.6% lower than that of the control group (P <0.05). The pull-out force of the AP trajectory was 44.7% higher than that of the MP trajectory (P <0.05) and reached 97.4% of the MP trajectory in the control group (P >0.05).ConclusionAutomatic planning of the pedicle screw trajectory based on the CT value can obtain a higher screw pull-out force, which is a valuable new method of pedicle screw placement in osteoporotic vertebral bodies.

An Automatic Planning-Based Attack Path Discovery Approach from IT to OT Networks

With the convergence of IT and OT networks, more opportunities can be found to destroy physical processes by cyberattacks. Discovering attack paths plays a vital role in describing possible sequences of exploitation. Automated planning that is an important branch of artificial intelligence (AI) is introduced into the attack graph modeling. However, while adopting the modeling method for large-scale IT and OT networks, it is difficult to meet urgent demands, such as scattered data management, scalability, and automation. To that end, an automatic planning-based attack path discovery approach is proposed in this paper. At first, information of the attacking knowledge and network topology is formally represented in a standardized planning domain definition language (PDDL), integrated into a graph data model. Subsequently, device reachability graph partitioning algorithm is introduced to obtain subgraphs that are small enough and of limited size, which facilitates the discovery of attack paths through the AI planner as soon as possible. In order to further cope with scalability problems, a multithreading manner is used to execute the attack path enumeration for each subgraph. Finally, an automatic workflow with the assistance of a graph database is provided for constructing the PDDL problem file for each subgraph and traversal query in an interactive way. A case study is presented to demonstrate effectiveness of attack path discovery and efficiency with the increase in number of devices.

Formal Event-B Modeling of the MICONIC Application

Automatic planning has a de facto standard language called PDDL for describing planning problems. The dynamic analysis tools associated with this language do not allow sufficient verification and validation of PDDL descriptions. Indeed, these tools, namely planners and validators, allow a posteriori error detection. In this paper, we recommend a formal approach coupling the two languages Event-B and PDDL. Event-B supports a formal development process based on the refinement technique with mathematical proofs. Thus, we propose a refinement strategy for obtaining reliable PDDL descriptions from an ultimate Event-B model that is correct by construction. The correctness is guaranteed via the verification and validation tools supported by Event-B. We have chosen the MICONIC application managing modern elevators to illustrate our approach while recognizing that the MICONIC application is already modeled in PDDL without formal proof of its correctness.

The Safety and Effectiveness of Automatic Pedicle Screw Trajectory Planning Based on CT Values: An in Vitro Osteoporosis Model Study.

BackgroundPedicle screw placement in patients with osteoporosis is a serious clinical challenge. The bone mineral density (BMD) of the screw trajectory has been positively correlated with the screw pull-out force, while the CT value has been linearly correlated with the BMD. The purpose of this study was to establish an in vitro osteoporosis model and verify the safety and effectiveness of automated pedicle screw planning software based on CT values in this model.MethodsTen vertebrae (L1-L5) of normal adult pigs were randomly divided into a decalcification group and a control group. In the decalcification group, the vertebral bodies were decalcified with Ethylenediaminetetraacetic acid (EDTA) to construct an in vitro osteoporosis model. In the decalcification group, automatic planning (AP) and manual planning (MP) were used to plan the pedicle screw trajectory on the left and right sides of the pedicle, respectively, and MP was used on both sides of the control group. CT values of trajectories obtained by the two methods were measured and compared. Then, 3D-printed guide plates were designed to assist pedicle screw placement. A biomechanical instrument was used to measure the pull-out force of the trajectory obtained by the two methods.ResultsAfter decalcification, the T' value of the vertebral body decreased from -0.03 ± 1.03 to -3.03 ± 0.29 (P <0.05). In the decalcification group, the MP trajectory CT value was 2167.28 ± 65.62 Hu, the AP trajectory CT value was 2723.96 ± 165.83 Hu, and the MP trajectory CT value in the control group was 2242.94 ± 25.80 Hu (P<0.05). In the decalcified vertebrae, the screw pull-out force of the MP group was 48.6% lower than that of the control group (P <0.05). The pull-out force of the AP trajectory was 44.7% higher than that of the MP trajectory (P <0.05) and reached 97.4% of the MP trajectory in the control group (P >0.05).ConclusionAutomatic planning of the pedicle screw trajectory based on the CT value can obtain a higher screw pull-out force, which is a valuable new method of pedicle screw placement in osteoporotic vertebral bodies.

Polyvariable conditionally dependent predicates in the knowledge representation model of autonomous mobile intelligent agents

Показано, что известные модели представления и обработки знаний не позволяют построить интеллектуальный решатель задач автономных мобильных интеллектуальных агентов, способных выполнять сложные задания в априори неописанных нестабильных условиях проблемной среды. Для решения данной актуальной проблемы в статье предлагаются типовые конструкции модели представления знаний безотносительно к конкретной предметной области, строящиеся на основе полипеременных условно-зависимых предикатов. Приведена структура данного вида предикатов и определены условия, при выполнении которых, в результате означивания входящих в них различного сорта переменных, получаются истинные высказывания, характеризующие необходимые условия для достижения стоящих подцелей и целей поведения в текущей ситуации нестабильной проблемной среды. Разработаны различные по назначению типовые элементы модели представления знаний автономных интеллектуальных агентов, позволяющие формировать на их основе различные по сложности программы целенаправленной деятельности связанные с выполнением сформулированного им задания. Отмечено, что дальнейшее развитие полученных в настоящей работе результатов связано с формализацией мыслительных актов и разработкой инструментальных средств обработки знаний для построения алгоритмов автоматического планирования целенаправленного поведения автономных мобильных интеллектуальных агентов в нестабильных недоопределенных условиях функционирования. It is shown that the known models of knowledge representation and processing do not allow constructing an intelligent problem solver for autonomous mobile intelligent agents capable of performing complex tasks in a priori undescribed unstable conditions of a problematic environment. To solve this topical problem, the article proposes standard constructions of a knowledge representation model, without reference to a specific subject area, based on polyvariable conditionally dependent predicates. The structure of this type of predicates is given and the conditions are determined under which, as a result of the valuation of variables included in them, true statements are obtained that characterize the necessary conditions for achieving behavioral sub goals and goals in the current situation of an unstable problematic environment. The standard and different in purpose elements of knowledge representation model for autonomous intelligent agents have been developed, which make it possible to form programs of purposeful activity of different complexity associated with the implementation of the formulated task. It is noted that further development of the results obtained in this work is associated with the formalization of mental acts and the development of knowledge processing tools for constructing automatic planning algorithms of the purposeful behavior of autonomous mobile intelligent agents in unstable underdetermined conditions.

Study on the improved internal feedback system of Rapidplan model

Objective: To study whether an interactive improved internal feedback system with the model can be established, we aimed to compare the plans generated by two automatic planning models generated under the same conditions.Methods: 70 cases of pelvic patients were selected. Intensity modulated radiation therapy (IMRT) plans (P0) generated by clinical model (M0) were imported into Rapidplan model, in order to establish dose volume histogram (DVH) predicted model through automatic planning model in clinical used, and the new Rapidplan model (M1) was generated by training and structure matching settings. 70 new IMRT plans (P1) were generated by M1, and new Rapidplan model (M2) was training by P1. By the same way, 70 IMRT plans (Plan2) were generated by M2. Dosimetric differences between P1 and P2 were compared and analysised.Results: From the inside of the model, the values of R22 and X22 in P2 were higher than those in P1, and the CD values of bladder, right femoral head and rectum in P1 were higher than those of corresponding organs in P2. The SR value of bladder and the SR and DA values of left femoral head and right femoral head in P1 were lower than those of P2. In terms of planning, the D2, D98 and HI in P1 were better than those in P2 (P<0.01), the bladder V10 and left femoral head V40 in P2 were lower than those in P1 by 0.08% and 0.15%, respectively (P<0.05), the others in P2 were higher than those in P1 (P<0.05) except the bladder V20, Dmean, rectum V10, V20, V30, right femoral head V10 and V40; and the MUs of P2 was lower than that of P1 for 132.2 (P<0.05).Conclusion: The stability of M2 is stronger than that of M1. Therefore, it can be considered that the interactive improved internal feedback system within the model of "plan-model-plan-model" is feasible and meaningful.

Automatic planning of paediatric craniofacial deformities: new virtual facial-symmetry operative detection

Background: The correction of craniofacial deformities is an ongoing challenge in maxillofacial surgery. However, conventional measurement methods for treatment planning are not appropriate for craniofacial surgery. Computer-assisted approaches can improve surgical outcomes. A new, non-invasive, patient-specific automatic method, proposed here, has been tested for assisting the surgeon in preoperative planning. Case Presentation: In the case reported, the described method allows effective surgery planning that led to a significant decrease in asymmetries in the orbital region. Conclusion: The multidisciplinary collaborative approach is a central element for the construction of effective personalized procedures and for the conception of new surgical approaches. The here proposed technology offers a good level of feasibility and has an achievable potential for breakthroughs in the improvement of facial deformities surgical treatment, thus representing an overwhelmingly useful tool in a clinical setting.