Anatomic models are important in medical education and pre-operative planning as they help students or doctors prepare for real scenarios in a risk-free way. Several experimental anatomic models were made with additive manufacturing techniques to improve geometric, radiological, or mechanical realism. However, reproducing the mechanical behavior of soft tissues remains a challenge. To solve this problem, multi-material structuring of soft and hard materials was proposed in this study, and a three-dimensional (3D) printer was built to make such structuring possible. The printer relies on extrusion to deposit certain thermoplastic and silicone rubber materials. Various objects were successfully printed for testing the feasibility of geometric features such as thin walls, infill structuring, overhangs, and multi-material interfaces. Finally, a small medical image-based ribcage model was printed as a proof of concept for anatomic model printing. The features enabled by this printer offer a promising outlook on mimicking the mechanical properties of various soft tissues.

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Silicone rubbers are relatively new in additive manufacturing, with only a few commercial printing services and reports on custom-built printers available. Publications and standards on calibration and accuracy assessment are especially lacking. In this study, the printhead calibration process of a custom-built silicone printer is explained, and a set of test objects is proposed and evaluated. The printer in use is based on an open-source filament printer, capable of multi-material printing with silicone rubbers and thermoplastic polymers. Three different high-viscosity single-component liquid silicone rubbers and one polylactic acid thermoplastic filament were used as printing materials. First, the calibration process of the silicone printhead was conducted, and the dependency of the dosing accuracy on silicone viscosity, nozzle diameter and extrusion speed was evaluated. Second, various test specimens were proposed and printed to characterize the accuracy and geometric limitations of this printer. These test parts contained features such as thin walls, slender towers, small holes and slots, unsupported overhangs and bridges. It was concluded that silicone viscosity strongly affects geometric inaccuracies. Design recommendations were deducted from the results, advising for wall thicknesses above 1 mm, slenderness ratios below 2, bridging lengths below 2 mm and unsupported overhang angles below 30°.

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A laparoszkópos technika napjainkra a sebészeti gyakorlatban széles körben elterjedt hazánkban is, azonban hatékony és etikus oktatása komplex szimulációs eszköztárat igényel. Ezek az oktatóeszközök fizikailag megvalósított boksztré-nerek vagy számítógépes szimulátorok, esetleg ezek kombinációjaként jelennek meg a piacon. Közleményünkben támpontot kívánunk adni a laparoszkópos oktatóeszközök kiválasztásához a kereskedelmi forgalomban kapható szimulátorok áttekintésével és főbb tulajdonságaik, funkcióik szisztematikus összefoglalásával. Az egyes rendszerek jellemzése mellett értékeljük a laparoszkópos oktatásra vonatkozó szakirodalmat, és kitérünk a megfigyelhető fejleszté-si trendekre. A közlemény kitér a boksztrénerek és a számítógépes virtuális valóság szimulátorok közötti különbségekre, illetve betekintést nyújt a robotsebészeti és a teljes műtéti folyamatot célzó szimulátorok világába. Orv Hetil. 2017; 158(40): 1570-1576. Kulcsszavak: laparoszkópos oktatás, boksztréner, MIS-szimulátor, robotsebészeti szimulátor Tools for laparoscopic skill development -available trainers and simulatorsThe laparoscopic minimally invasive surgical technique is widely employed on a global scale. However, the efficient and ethical teaching of this technique requires equipment for surgical simulation. These educational devices are present on the market in the form of box trainers and virtual reality simulators, or some combination of those. In this article, we present a systematic overview of commercially available surgical simulators describing the most important features of each product. Our overview elaborates on box trainers and virtual reality simulators, and also touches on surgical robotics simulators, together with operating room workflow simulators, for the sake of completeness. Apart from presenting educational tools, we evaluated the literature of laparoscopic surgical education and simulation, to provide a complete picture of the unfolding trends in this field. A laparoszkópos sebészet napjainkra széles körben elterjedt a klinikai gyakorlatban, így a laparoszkópos sebésze-ti készségek megfelelő oktatása és felmérése fontos kér-déskörré vált [1]. A minimálisan invazív sebészethez (MIS) szükséges koordinációs készségek nagymértékben eltérnek a nyitott műtéteknél szükségesektől. A kétdi-menziós rendszereknél a kamerával történő navigációnál a síkképernyő miatt lecsökken a mélységérzékelés, és a

Anatomic models have an important role in the medical domain. However, soft tissue mechanical properties’ representation is limited in mass-produced and 3D-printed models. In this study, a multi-material 3D printer was used to print a human liver model featuring tuned mechanical and radiological properties, with the goal of comparing the printed model with its printing material and real liver tissue. The main target was mechanical realism, while radiological similarity was a secondary objective. Materials and internal structure were selected such that the printed model would resemble liver tissue in terms of tensile properties. The model was printed at 33% scaling and 40% gyroid infill with a soft silicone rubber, and silicone oil as a filler fluid. After printing, the liver model underwent CT scanning. Since the shape of the liver is incompatible with tensile testing, tensile testing specimens were also printed. Three replicates were printed with the same internal structure as the liver model and three more out of silicone rubber with 100% rectilinear infill to allow a comparison. All specimens were tested in a four-step cyclic loading test protocol to compare elastic moduli and dissipated energy ratios. The fluid-filled and full-silicone specimens had initial elastic moduli of 0.26 MPa and 0.37 MPa, respectively, and featured dissipated energy ratios of 0.140, 0.167, 0.183, and 0.118, 0.093, 0.081, respectively, in the second, third, and fourth loading cycles. The liver model showed 225 ± 30 Hounsfield units (HU) in CT, which is closer to real human liver (70 ± 30 HU) than the printing silicone (340 ± 50 HU). Results suggest that the liver model became more realistic in terms of mechanical and radiological properties with the proposed printing approach as opposed to printing only with silicone rubber. Thus, it has been demonstrated that this printing method enables new customization opportunities in the field of anatomic models.