Computer-based Planning Research Articles

Implantation accuracy of custom-made glenoid implants for treating severe glenoid bone deficiencies with reverse shoulder arthroplasty

BackgroundCustom-made three dimensional–printed glenoid implants for reverse shoulder arthroplasty are a modern treatment option for severe glenoid bone deficiencies. The potential advantages of not only achieving primary stability but also being able to realize the preoperative plan in terms of implantation accuracy at the same time have not yet been sufficiently investigated. The purpose of this study was to quantify the implantation precision of custom-made glenoid implants. MethodsTwelve consecutive patients with severe glenoid bone defects were treated between May 2019 and August 2020 using a custom-made glenoid implant (ProMade) (LimaCorporate, San Daniele, Italy) with reverse shoulder arthroplasty at a single hospital. All patients were eligible for inclusion and could be enrolled in this institutional review board–approved study. The immediate postoperative computer tomography–evaluated position of the glenoid implant was compared with the preoperative computer-based plan, on which the manufacturing process was based. As a result of this comparison, deviation measurements in six degrees of freedom (inclination, version, mediolateral offset, anteroposterior offset, superoinferior offset, and roll rotation) emerged. ResultsThe absolute average (mean value ± standard deviation) implantation deviation related to the plan was 1.6° ± 5.4° for version, 1.9° ± 4.1° for inclination, 0.3 mm ± 3.3 mm for mediolateral offset, 0.1 mm ± 1.9 mm for anteroposterior offset, 0.0 mm ± 2.4 mm for superoinferior offset, and 1.0° ± 6.3° for roll rotation. The augment volume averaged 9.0 cm³ ± 2.6 cm³. All custom-made glenoid implants were implanted with a subjectively sufficient primary stability. ConclusionThis study gives an indication that custom-made three dimensional–printed glenoid implants can be implanted with statistically high accuracy. To evaluate the clinical benefit and radiographic stability, a longer follow-up investigation is needed.

Accurate Liver Border Identification Model in CT Scan Images

The liver is an important organ in human body with certain variations in its edges, color, shape and pixel intensity distribution. These uncertainties may be because of various liver pathologies, hereditary or both. Along with it, liver has close proximity to its nearby organs. Hence, identifying liver in scanned images is a challenging step in image processing. This task becomes more imprecise when liver diseases are present at the edges. The liver segmentation is prerequisite for liver volumetry, computer-based surgery planning, liver surgery modelling, surgery training, 3D view generation, etc. The proposed hybrid segmentation method overcomes the problems and identifies liver boundary in Computed-Tomography (CT) scan images accurately. In this paper, the first step is to study statistics of pixel intensity distribution within liver image, and novel methodology is designed to obtain thresholds. Then, threshold-based segmentation is applied which separates the liver from abdominal CT scan images. In the second step, liver edge is corrected using improved chain code and Bresenham pixel interconnection methods. This provides a precise liver image. The initial points are located inside the liver region without user interventions. These initial points evolve outwardly using Fast Marching Method (FMM), identifying the liver boundary accurately in CT abdominal scan images.

Increasing teacher treatment fidelity to cover, copy, compare through consultation and computer-based implementation planning

ABSTRACT Available data indicate educators struggle to implement interventions consistently across time, which negatively impacts student outcomes. Implementation strategies have been developed to improve treatment fidelity, but many require time and staffing demands that can be unfeasible in practice. The primary purpose of this study was to extend the literature on one such strategy, implementation planning, by evaluating the effectiveness of computer-based implementation planning (CBIP) to improve teachers’ treatment fidelity to cover, copy, compare (CCC). Teachers were asked to implement CCC with nominated students having difficulty with mathematics fluency. All teachers demonstrated low-to-moderate adherence and moderate-to-high quality during initial implementation. Following the completion of CBIP, teachers consistently demonstrated substantially improved levels of adherence and moderately improved quality. Teachers rated CBIP to be socially valid. Implications and future directions related to the present findings are discussed.

A single-use, size-specific, nylon arthroplasty guide: a preliminary study for hip resurfacing.

In arthroplasty surgery, positioning of the components must be accurate and reproducible to avoid complications. Conventional guides are often used to align a component, but they require surgical skill and experience, and are prone to error. To this end, a single-use, size-specific, nylon guide (single-use nylon guide) has been developed for the purpose of increasing the accuracy without adding extra cost to the operation. The effectiveness of this type of guide was evaluated in using a synthetic bone study. A total of 66 synthetic femurs with the same osteoarthritic morphology were prepared. 3 surgeons participated in the experiments, and each surgeon created a drill hole for the femoral component by using the single-use nylon guide or a commercially-available, conventional, metal, neck-based guide (conventional guide). Anteversion, inclination, and insertion point acquired by the guide were compared between the guides, between surgeons, and to the computer-based plan. Anteversion acquired by the single-use nylon guide (6.7° [4.9-11.5°]) was significantly closer to the plan (14.6°) than that acquired by the conventional guide (4.3° [2.4-8.6°]) (p = 0.03). The insertion point was also significantly closer to the plan for the single-use nylon guide (3.8 mm ± 1.6 mm) than the conventional guide (5.7 mm ± 2.4 mm) (p < 0.001). No significant difference was found for the inclination (p = 0.76). A single-use, size-specific nylon guide was effective in acquiring a higher accuracy and precision in anteversion and insertion point than a conventional guide in this synthetic bone, hip resurfacing arthroplasty study. The use of single-use guides in other orthopaedic procedures should be explored.

Obtaining the distribution of quiescent periods directly from the power spectral densities of Sea waves

There is a growing practical interest in the ability to increase the sea states at which marine operations can be safely undertaken by exploiting the quiescent periods that are well known to exist under a wide range of sea conditions. While the actual prediction of quiescent periods at sea for the control of operations is a deterministic process, the long term planning of future maritime tasks that rely on these quiescent periods is a statistical process involving the anticipated quiescence properties of the forecasted sea conditions in the geographical region of interest. It is in principle possible to obtain such data in tabular form either large scale simulation or from field data. However, such simulations are computationally intensive and libraries of appropriate field data are not common. Thus, it is clearly attractive to develop techniques that exploit standard wave spectral models for describing the quiescence statistics directly from such spectra. The present study focuses upon such techniques and is a first step towards the production of a computationally low-cost quiescence prediction tool and compares its efficacy against simulations. Two significant properties emerge for a large class of wave spectral models that encompasses the ubiquitous Neumann and Pierson Moskowitz or Bretschneider forms. Firstly, the auto-correlation function of the wave profile that are required to produce the quiescence property can be obtained analytically in terms of standard special functions. This considerably reduces the computational cost making desktop computer-based planning tools a reality. Secondly, for each class of these parametric spectra, the probability of a given number of consecutive wave heights (normalised to the significant wave heights) less than some critical value is in fact independent of absolute wave height. Thus, for a broad class of practically interesting wave spectra all that is required to obtain the statistical distribution of the quiescent periods is simple rescaling.

Traditional face-bow transfer versus three-dimensional virtual reconstruction in orthognathic surgery

Face-bow transfer is an essential step in articulator-based orthognathic surgery planning. However, it can be a source of inaccuracy. Virtual computer-based planning avoids this error through the use of direct patient-related three-dimensional imaging data. The aim of this prospective observational study was to determine the error of face-bow transfer three-dimensionally and correlate it to the different types of malocclusion. Orthognathic surgery performed on 38 patients (10 male, 28 female; mean (standard deviation) age 24.7 (6.9) years) was planned twice: first articulator-based with plaster models and second computer-based with surgery planning software. Both models were digitized and compared regarding the angle between the Frankfort horizontal plane and the occlusal plane. In most cases, the angle in the sagittal dimension was higher in the articulator-based model than in the computer-based model. The angle in the transverse dimension was as often under- as over-represented. The type of malocclusion, i.e. skeletal class, vertical relationship, and degree of asymmetry, had no significant impact on the amount of error. In conclusion, this study indicates that computer-based planning should be considered as an advantageous alternative in orthognathic surgery planning.

Modular design of versatile surgical mini-robots

Abstract Surgical robots have been introduced in the field of Computer Assisted Surgery (CAS) to assist the surgeon by providing an accurate link between the computer-based plan and the exact (a) positioning or (b) dynamic path control of an instrument on the operating site respectively. Whereas initial systems mostly have been based on an active supervisory control scheme of industrial robots with large universal workspaces, later on specialized miniaturized kinematics have been proposed, with restricted workspaces adapted to specific applications in order to ease handling and provide inherent safety properties. However, this specialization resulted in even narrower fields of application, low quantities and higher costs. Modularization seems to be a key factor to combine the benefits of both approaches. In this paper two modular robotic solutions, validated in the context of their purpose, are analysed regarding their modular design. Based on this, the potential of modularity for instrument guiding tasks in surgery is discussed.

A Framework for Assessing and Characterizing Cellular Production Structures

An increased volatility of market demands and customized products force companies to continuously monitor the right configuration of their production to ensure production at competitive costs. One crucial success factor for companies is the right configuration of their production structure. Driven by the evolution of computer-based planning methods, up to several thousand possible production structures can be examined and evaluated automatically. This article presents a framework for assessing and characterizing production structures to enable production supervisors for fast and profound decisions by providing adequate decision support. The framework, consisting of the parts performance and structural indicators and visualization, is applied using a real industrial case.

Computerized Planning of Prostate Cryosurgery and Shape Considerations.

The current study aims to explore possible relationships between various prostate shapes and the difficulty in creating a computer-based plan for cryosurgery. This research effort is a part of an ongoing study to develop computational means in order to improve cryosurgery training and education. This study uses a computerized planner—a key building block of a recently developed prototype for cryosurgery training. The quality of planning is measured by the overall defect volume, a proprietary concept which refers to undercooled areas internal to the target region and overcooled areas external to it. Results of this study numerically confirm that the overall defect volume decreases with an increasing number of cryoprobes, regardless of the geometry of the prostate. However, the number of cryoprobes required to achieve the smallest possible defect may be unrealistically high (<30). Results of this study also demonstrate that the optimal cryoprobe layout is associated with a smaller defect for symmetric prostate geometries and, independently, for prostate models that better resemble a sphere. Furthermore, a smaller defect is typically achieved when the urethra passes through the center of the prostate model. This study proposes to create a cryoprobe convex hull for the purpose of initial planning, which is a subdomain similar in shape to the prostate but at a reduced size. Parametric studies indicate that a cryoprobe convex hull contracted by 7 to 9 mm in all directions from the prostate capsule serves as a quasi-optimal initial condition for planning, that is, a preselected number of cryoprobes placed in the cryoprobe convex hull yields favorable results for optimization. The cryoprobe convex hull could accelerate computer-based planning, while also being adopted as a concept for traditional cryosurgery training, when computerized means are absent.

Airway and Esthetics – State of the Art Chin Surgery for OSA

Genioglossus advancement is a sound and well established surgical procedure for the management of obstructive sleep apnea (OSA). It may be used in isolation or combined with other surgical techniques with the goal of opening the posterior airway space. Using virtual surgical planning (VSP), this technique provides a functional benefit by advancing the genioglossus muscle, while also providing an esthetic benefit to ideal chin position. The VSP-assisted technique presented offers confidence in capturing the geniotubercle with preoperative computer-based planning. Fabrication of an occlusal-borne cutting guide provides an increase in surgical precision. This technique allows for ideal treatment of the dentofacial deformity in the OSA population.

Computer-Assisted 3-Dimensional Reconstructions of Scaphoid Fractures and Nonunions With and Without the Use of Patient-Specific Guides: Early Clinical Outcomes and Postoperative Assessments of Reconstruction Accuracy

To present results regarding the accuracy of the reduction of surgically reconstructed scaphoid nonunions or fractures using 3-dimensional computer-based planning with and without patient-specific guides. Computer-based surgical planning was performed with computed tomography (CT) data on 22 patients comparing models of the pathological and the opposite uninjured scaphoid in 3 dimensions. For group 1 (9 patients), patient-specific guides were designed and manufactured using additive manufacturing technology. During surgery, the guides were used to define the orientation of the reduced fragments. The scaphoids in group 2 (13 patients) were reduced with the conventional freehand technique. All scaphoids in both groups were fixed with a headless compression screw or K-wires, and all bone defects (except one) were filled with autologous bone grafts or vascularized grafts. Postoperative CT scans were acquired 2 or more months after the operations to monitor consolidation and compare the final result with the preoperative plan. The clinical results and accuracy of the reconstructions were compared. In group 1, 8 of 9 scaphoids healed after 2 to 6 months, and partial nonunion after 9 months was observed in one patient. In group 2, 11 of 13 scaphoids healed between 2 and 34 months whereas 2 scaphoids did not consolidate. Comparison of the preoperative and postoperative 3-dimensional data revealed an average residual displacement of 7° (4° in flexion-extension, 4° in ulnar-radial deviation, and 3° in pronation-supination) in group 1. In group 2, residual displacement after surgery was 26° (22° in flexion-extension, 12° in ulnar-radial deviation, and 7° in pronation-supination). The difference in the accuracy of reconstruction was significant. Although the scaphoid is small, patient-specific guides can be used to perform scaphoid reconstructions. When the guides were used, the reconstructions were significantly more anatomic compared with those resulting from the freehand technique. Therapeutic III.

Brachytherapy: state‐of‐the‐art radiotherapy in prostate cancer

Brachytherapy: state‐of‐the‐art radiotherapy in prostate cancer

Computer-based surgical planning and custom-made titanium implants for cranial fibrous dysplasia.

The procedure of reconstruction after the removal of cranial fibrous dysplasia (FD) must be precise to achieve good functional and aesthetic results. Intraoperative modeling of implants is difficult and may cause cosmetic disturbances. To present our experience with the treatment of cranial FD using preoperative computer-based surgical planning of tumor removal with reconstruction of the cranium with custom-made titanium implants. Four patients underwent surgical treatment for cranial FD over a 2-year period. All patients were male with a mean age of 25.25 years and had monostotic-type FD. Computed tomography (CT) with 0.5-mm slices was obtained preoperatively. Computer-based planning of the tumor removal was performed, and a template was created by the computer to determine the margins of tumor removal. After this procedure, the preoperative computer-based construction of the titanium implant was performed. The patients underwent surgical treatment, and the tumor was removed with the use of this template. Then, the titanium implant was inserted onto the bone defect and fixed with mini-screws. Patients were followed up by periodic CT scans. The histological diagnosis of all patients was FD. No intraoperative or postoperative complications have occurred. Postoperative CT scans showed complete tumor removal and confirmed appropriate cosmetic reconstruction. The mean follow-up period was 15.25 months. Computer-based surgical planning associated with the production of custom-made titanium implants is a highly promising method for the treatment of cranial FD. Better radiological and cosmetic outcomes could be obtained by this technique with interdisciplinary work with medical designers.

AffectRoute – considering people’s affective responses to environments for enhancing route-planning services

Humans perceive and evaluate environments affectively. Some places are experienced as unsafe, while some others as attractive and interesting. These affective responses to environments influence people’s daily behavior and decision-making in space, e.g., choosing which route to take, or which place to visit. In this article, we report on a methodology of using people’s affective responses to environments for enhancing computer-based route planning. More specifically, we explore a crowdsourcing approach to model and collect people’s affective responses to environments; an Affect-Space-Model and a mobile application are developed to facilitate this crowdsourcing approach; a routing algorithm (named AffectRoute) is then proposed to aggregate and integrate the collected data for automatic route planning. Evaluation with human participants shows that the routes generated by considering people’s affective responses to environments are significantly preferred over the conventional shortest ones, which are employed in car navigation systems and many online route planners. In conclusion, considering people’s affective responses to environments contributes to the improvement of automatic route planning. The proposed method can be integrated into existing route-planning services (e.g., location-based services) to provide users with more satisfying routing results.

Treatment of metastatic thoracolumbar tumors by percutaneous vertebroplasty combined with interstitial implantation of ¹²⁵I seeds

To explore the value of percutaneous vertebroplasty combined with interstitial implantation of ¹²⁵I seeds in the treatment of metastatic thoracolumbar tumors. Based on the CT images before ¹²⁵I seed implantation, a computer-based treatment planning system (TPS) was used to determine the optimal seed distribution. Under CT guidance and local anaesthesia, ¹²⁵I seeds were implanted into 22 osseous metastatic lesions in 18 patients. Based on the CT images after the implantation, quality check was carried out with TPS. DSA (digital subtraction angiography)-guided vertebroplasty was performed under local anaesthesia, and bone cement was injected into the vertebrae through pedicle of vertebral arch. All the 18 patients received percutaneous vertebroplasty combined with interstitial implantation of ¹²⁵I seeds. Every vertebra was injected with 2-6 ml bone cement, average 3.5 ml, and was injected with ¹²⁵I seeds 16-34 pills, average 26 pills. At 2-months follow-up, their numerical rating scale (NRS) pain scores were 7.12 ± 1.48 before and 2.26 ± 1.07 after treatment, with a significant difference (P < 0.05). Percutaneous vertebroplasty combined with interstitial implantation of ¹²⁵I seeds is a minimally invasive procedure with small wound and minor complications, and no need of external radiation therapy. It is effective in the alleviation of pain in metastatic thoracolumbar tumor patients, restrains the tumor growth, and improves the quality of life. It is a promising minimally invasive method in the treatment of metastatic thoracolumbar tumors.

Concepts of flapless surgery for implantation

During the past years a rapid progress was seen in the field of three-dimensional analysis using the digital volume tomography (DVT) and computer-based planning in dental implant patients. The resulting increase in accuracy of visualization of the operation field prior to surgery allowed for a reduction in the invasiveness of the intervention by minimization of the amount of flap elevation. Flapless surgery seems to be a new promising technique, which reduced post operative pain and swelling. In a recent minipig study of our group it was shown that flapless surgery results in a significantly increased expression of epithelial adhesion molecules, like laminin or integrin, in the sulcular epithelium.

MR Imaging of Prostate Cancer in Radiation Oncology: What Radiologists Need to Know

Radiation therapy (RT) is one of the principal treatment modalities for localized or locally advanced prostate cancer. The two major forms of RT for prostate cancer are external-beam RT (EBRT) with a photon or proton beam and brachytherapy. With modern conformal techniques for EBRT (three-dimensional conformal RT, intensity-modulated RT, and image-guided RT) and advanced computer-based planning systems for brachytherapy, the dose can be more precisely delivered to the prostate while reducing unnecessary radiation to normal tissue. The dominant intraprostatic tumor can be targeted with a higher dose, so-called dose painting. Magnetic resonance (MR) imaging plays a pivotal role in pretreatment assessment of prostate cancer. Multiparametric MR imaging, a combination of anatomic and functional MR imaging techniques (diffusion-weighted imaging, dynamic contrast material-enhanced imaging, and MR spectroscopy), significantly improves the accuracy of tumor localization and local staging. For pretreatment planning, anatomic MR imaging provides highly accurate local staging information, particularly about extraprostatic extension and seminal vesicle invasion. The dominant intraprostatic tumor and local recurrence in the prostatectomy bed can be better localized with multiparametric MR imaging for dose painting. MR imaging allows excellent delineation of the contours of the prostate and surrounding structures. It can also be used in early posttreatment evaluation after brachytherapy.

The LiverSurgeryTrainer: training of computer-based planning in liver resection surgery

The training of liver surgeons depends on local conditions such as the specialization of the clinic, the spectrum of cases, and the instructing surgeons. We present the LiverSurgeryTrainer a software application to support the training of prospective surgeons in preoperative decision making. The LiverSurgeryTrainer visualizes radiological images, volumetric information, and interactive 3D models of patients' liver anatomy. In addition, it provides special interaction techniques and tools to perform individual resections on the training data. To assess the correctness of decisions made by the learner, comments and decisions from experienced liver surgeons are provided for each case. To complete the case, additional material concerning the actual surgery (e.g., videos, reports) is presented. The application workflow is derived from a scenario-based design process and is based on an instructional design model. The LiverSurgeryTrainer was evaluated in several steps. A formative usability evaluation identified workflow and user interface flaws that were resolved in further development process. A summative evaluation shows the improvement of the LiverSurgeryTrainer in nearly all analyzed aspects. First results of a learning success evaluation show that learners experience a learning effect. Our training system allows surgeons to train procedures and interaction techniques for computer-based planning of liver interventions. The evaluations showed acceptance and usability.

Development and Implementation of an Adapted Evacuation Planning Methodology in the Framework of Emergency Management and Disaster Response: A Case Study Using TransCAD

The nature of natural disasters is often unpredictable, so it is extremely important that sufficient planning be done to evaluate the preparedness, the system response, and the ability of transportation infrastructures to handle evacuation traffic. This article presents an adapted evacuation planning methodology that essentially incorporates the traditional four-step planning model and dynamic traffic assignment. The authors utilize the transportation network in Western Massachusetts as an example to test the effectiveness of the proposed methodology using two with-notice hurricane evacuation scenarios. The analysis is performed by using the off-the-shelf computer-based planning software package TransCAD to assist the four-step transportation planning process. By altering inputs and using dynamic traffic assignment, TransCAD can be used to predict how the transportation system behaves during an evacuation. Two scenarios are used as the basis of the evacuation modeling. A production-attraction model is presented to replicate the behavior of evacuees. The production-attraction model results are compared with a series of reports, and the model falls within the recommendations of these reports. Several different evacuation speeds are examined for two different study areas. The Results section shows the outputs that can be garnered from the program such as the clearance time, critical locations, V/C ratios, and location-to-location travel times. Finally, recommendations are made on how these results can be used to aid planners. It is worth mentioning that the proposed evacuation modeling methodology can be extended and implemented in other places with minor modifications of network topology and localized travel behavior data.

Bringing Robustness to Patient Flow Management Through Optimized Patient Transports in Hospitals

Intrahospital transports are often required for diagnostic or therapeutic reasons. Depending on the hospital layout, transportation between nursing wards and service units is either provided by ambulances or by trained personnel who accompany patients on foot. In many large German hospitals, the patient transport service is poorly managed and lacks work-flow coordination. This contributes to higher hospital costs (e.g., because a patient is not delivered to the operating room on time) and to patient inconvenience (e.g., because of long waiting times). We designed a computer-based planning system, Opti-TRANS©, that supports all phases of the transportation flow, including travel booking, dispatching transport requests, and monitoring and reporting trips in real time. The methodology, which we developed to solve the underlying optimization problem—a dynamic dial-a-ride problem with hospital-specific constraints, draws on fast heuristic methods to ensure the efficient and timely provision of transports. We illustrate the strong impact of Opti-TRANS on the daily performance of the patient transportation service of a large German hospital. The major benefits of Opti-TRANS include streamlined transportation processes and work flow, significant savings, and improved patient satisfaction. Moreover, it has contributed to increased awareness among hospital staff of the importance of implementing efficient logistics practices.