Abstract
In this paper, we aim at providing results concerning the application of desktop systems for rapid prototyping of medical replicas that involve complex shapes, as, for example, folds of a colon. Medical replicas may assist preoperative planning or tutoring in surgery to better understand the interaction among pathology and organs. Major goals of the paper concern with guiding the digital design workflow of the replicas and understanding their final performance, according to the requirements asked by the medics (shape accuracy, capability of seeing both inner and outer details, and support and possible interfacing with other organs). In particular, after the analysis of these requirements, we apply digital design for colon replicas, adopting two desktop systems. The experimental results confirm that the proposed preprocessing strategy is able to conduct to the manufacturing of colon replicas divided in self-supporting segments, minimizing the supports during printing. This allows also to reach an acceptable level of final quality, according to the request of having a 3D presurgery overview of the problems. These replicas are compared through reverse engineering acquisitions made by a structured-light system, to assess the achieved shape and dimensional accuracy. Final results demonstrate that low-cost desktop systems, coupled with proper strategy of preprocessing, may have shape deviation in the range of ±1 mm, good for physical manipulations during medical diagnosis and explanation.
Highlights
Desktop systems seem to be advisable for medical replicas that can be adopted as tools for managing surgical planning or for better understanding specific patient-related aspects. ey can be able to translate, and with low costs, 2D DICOM (Digital Imaging and COmmunications in Medicine) analysis into a physical replica, helping a proper perception of actual shapes and lengths
A quantitative comparison of the additive manufacturing (AM) replicas with the tessellation obtained from the DICOM has been obtained by some reverse engineering acquisitions. ey are related to the first segment in the upper part of the colon
E digital preprocessing of the DICOM data has been approached according to the requirements of (a) making the replica partially opened, and (b) limiting surface postprocessing due to support removal. e opened area is the rectum one, which has been obtained as a thin-walled segment, with one removable shell. e other segments, instead, are filled in by honeycomb fill-in at 15%
Summary
Regardless of a specific AM process, in a digital design workflow, we can distinguish the following steps [24]:. (i) preprocessing that concerns with 3D model setup as suitable STL file (ii) CAM setup of the slicing and processing that consist in the manufacturing of the component (iii) postprocessing that pertains to the removal of the component from the manufacturing table and the removal of the outer supports and other operations necessary to guarantee final shape and roughness (gluing of separated parts, surface finishing, etc.) Each of these steps has its own workflow that can be specialized according to the specific field of application. CAM setup and processing (CAM) includes slicing that pertains to the selection of the layer direction and the subdivision of the 3D model into a set of sections, called slices, one over the other In this step, the necessity of splitting the replica into parts must to be evaluated. For example, does not work with polylactic acid (PLA)
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