Camillo Bandera

Accuracy of virtual reality and stereolithographic models in maxillo-facial surgical planning.

Computed tomography is a medical instrument that can be useful not only for diagnostic purposes, but also for surgical planning, thanks to the fact that it offers volumetric information which can be translated in three dimensional models. These models can be visualized, but also exported to Rapid Prototyping (RP) systems, that can produce these structures thanks to the rapidity and versatility of the technologies involved. The literature reports various cases of stereolithographic models used in orthopedic, neurological, and maxillo-facial surgery. In these contexts, the availability of a copy of the real anatomy allows not only planning, but also the practical execution of surgical operations, within the limitations of the materials. Nevertheless, the Rapid Prototyping model also presents some disadvantages that can be reduced if practical simulation is accompanied by virtual simulation, performed on a digital model. The purpose of this work is to examine and present the use of Virtual Reality (VR) and Rapid Prototyping for surgical planning in Maxillo-Facial surgery.

Analysis of existing methods for 3D modelling of femurs starting from two orthogonal images and development of a script for a commercial software package

BACKGROUND At present the interest in medical field about the generation of three-dimensional digital models of anatomical structures increases due to the widespread diffusion of CAS--computer assisted surgery--systems. Most of them are based on CT--computer tomography--or MR--magnetic resonance--data volumes but sometimes this information is not available; there are only few X-ray, ultrasound or fluoroscopic images. METHODS This paper describes the study and the development of a script for a commercial software package (3ds Max) able to reconfigure the template model of a femur starting from two orthogonal images representing the specific patients anatomy. RESULTS The script was used in several tests as summarized in this paper and the results appear to be interesting and acceptable, even for the medical experts that evaluated them. CONCLUSIONS The script developed in this work allows the generation of the 3D model of a femur in a very simple way (the user interface has been developed obeying to the main usability guidelines) and using a widespread commercial package. The quality of the results can be compared to the quality of more expensive and specialized systems.

Value analysis as a decision support tool in cruise ship design

In the cruise ship industry product development and production activities are really complex and must follow strict rules imposed by naval registries. Designers are frequently required to choose among several alternative solutions (e.g., materials, components, layouts, etc.). Because of time constraints, as a matter of fact, design decisions are made fast and in a reactive way, according to the particular case, without considering decisions made in the past and without using specific decision support tools. The final choice is often left to a single designers experience, whose selection criteria are unknown and not formalised. As a consequence there is no shared knowledge justifying the reason why a design solution has been chosen and whether it is the best one. We developed and implemented in Fincantieri S.p.A. – a leading company in the cruise ship industry – an original decision support tool, based on value analysis, designers can use to document and formalise their choices. Value analysis is a well known structured method to increase product value and/or cut costs, thus supporting the selection of the most valuable solution by means of objective parameters. We demonstrate that the proposed tool can also facilitate reuse of the available knowledge base on decisional criteria, increase interactions between people (design staff, buyers, shipyard personnel, etc.) involved in different stages of different value analysis projects, and reduce decision time.

The role of product feature relations in a knowledge based methodology to manage design modifications for product measurability

During product development, the verification process should already be considered at the design phase to ensure that the characteristics of the product are measured effectively and reliably. Moreover, the verification process may prove more effective if the inspector is aware of the specific designers intents. The development of the new ISO GPS (Geometrical Product Specifications) standards is mainly founded on these considerations. In accordance with the ISO GPS concepts, previous work developed a knowledge based system named Design GuideLines (DGLs). This system provides the designer with the knowledge concerning the manufacturing and verification procedures/tools and better links the manufacturing and verification processes to the designers activities/needs. Further research then exploited the DGLs to discover the relations among product features determined by a particular manufacturing process. This work again uses the DGLs to prove that further relations among product features may also be determined by the verification process. This knowledge helps designers in understanding the consequences of the modifications applied to the product features required to improve the measurability of the product. Moreover, inspectors can better manage the verification procedure knowing these relations among the product features.

Comparing parametric solid modelling/reconfiguration, global shape modelling and free-form deformation for the generation of 3D digital models of femurs from X-ray images

At present, computer assisted surgery systems help orthopaedic surgeons both plan and perform surgical procedures. To enable these systems to function, it is crucial to have at ones disposal 3D models of anatomical structures, surgical tools and prostheses (if required). This paper analyses and compares three methods for generating 3D digital models of anatomical structures starting from X-ray images: parametric solid modelling/reconfiguration, global shape modelling and free-form deformation. Seven experiences involving the generation of a femur model were conducted by software developers and different skilled users. These experiences are described in detail and compared at different stages and from different points of view.

Customising a Knowledge-Based System for Design Optimisation in Fused Deposition Modelling RP-Technique

In a Design For Manufacturing context, Rapid Prototyping techniques are some way still considered as “new technologies”: the peculiar characteristics of the manufacturing processes are not widely known and may deeply affect the final product functionality. A Knowledge Based System, the Design Guidelines — DGLs, was developed by our Research Group at the University of Udine; it evaluated the products design, in order to verify its feasibility by DMLS (Direct Metal Laser Sintering) Rapid Prototyping technique. During the evaluation process, the DGLs also keep into consideration the aspects relating the verification step, according to the ISO-GPS principles, thus enhancing the completeness of the tool. Aim of this work was to customise the DGLs for design optimisation in FDM (Fused Deposition Modelling), also evidencing the critical aspects and proposing alternative solutions. The contents and structure of the customised version of DGLs are presented in this work.

Validating CSCW strategies and applications for rapid product development in the investment casting process

The aim of this study is to apply and validate a general-purpose working methodology, derived from the analysis of processes which come from two different domains (the field of medicine and the preservation of cultural heritage), in the investment casting process. CSCW methods and tools have proven to be the best ‘gluing tool’ to bond the different activities, and thus heavily exploited during the customization of the general-purpose working methodology. This paper describes a case study performed in an industrial sector and related to the investment casting application field. It was chosen to test methodology and to demonstrate its wide applicability. The case study involved the realization of a centrifugal pump impeller, where the application of this CSCW-based methodology has delivered important results such as the reduction of product development time and the drastic reduction of production costs.

How Rapid Prototyping Process Parameters Could Affect the Product Design Phase: A KBS Approach

Considering the whole product life-cycle, product model is usually defined during the design phase, given a set of requirements and constraints belonging to the same domain. The use of different manufacturing and verification technologies may, however, profoundly affect the characteristics of the product, so that a re-design phase is often necessary. In previous work, a Knowledge Based System named Design GuideLines (DGLs) was developed, aiming to help the designers make the product model compatible with the requirements and constraints of the specific manufacturing and verification domains. During the DGLs development, the possibility emerged to exploit them in order to identify possible relations among product features. This aspect seems very important, further helping the designer to better understand the consequences of the modifications suggested by the DGLs and applied to the product model during the re-design phase. The present work aims to identify these relations among product features. The result of DGLs exploitation has been critically analyzed to highlight the link between manufacturing characteristics and product features, and, further, among features themselves. Unpredictable relations among the product features, given a particular Rapid Prototyping technology as manufacturing technology, have been discovered and exploited.Copyright

Ct-Based Reverse Engineering and Rapid Prototyping: Experiences in Different Application Domains

Current Rapid Prototyping (RP) techniques are becoming available in many different application domains and hence for a growing number of users, even if some features make them still usable by trained personnel only. The same evolution is happening for what concerns Computer Tomography (CT) activities: moving from medical diagnostic issues, now CT is used in industrial environments (quality testing, etc.), in artistic ones (non-destructive acquisition of data from monuments and similar), and, always in the medical field, during the process planning for surgery activities and the development of surgical tools.

Survey on Virtual Prototyping Technologies for Orthopedic Implants and Prosthesis Design

Nowadays, Virtual Prototyping (VP) methods are widely used for product design and development purposes. In particular, VP methods are now used also for the orthopedic products development process, to better understand the functional performance of prostheses or implants within the musculoskeletal system. In fact, developing validated virtual models of joints or of other anatomical structures may reduce design and prototyping costs and compress development cycles. The purpose of this paper is to point out first the state of art of both the VP technologies and the kinds of virtual models used in the medical field, with particular attention to those used for the design and development of orthopedic products. Then, it focuses on a qualitative analysis of some biomechanical simulation software packages (LifeMOD, AnyBody, and OpenSim) as tools for the improvement of the product design and development processes.© 2011 ASME