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Basics and applications of rapid prototyping medical models Sushant Negi, Suresh Dhiman and Rajesh Kumar Sharma Department of Mechanical Engineering, National Institute of Technology (NIT) Hamirpur, Hamirpur, India Abstract Purpose – This study aims to provide an overview of rapid prototyping (RP) and shows the potential of this technology in the field of medicine as reported in various journals and proceedings. This review article also reports three case studies from open literature where RP and associated technology have been successfully implemented in the medical field. Design/methodology/approach – Key publications from the past two decades have been reviewed. Findings – This study concludes that use of RP-built medical model facilitates the three-dimensional visualization of anatomical part, improves the quality of preoperative planning and assists in the selection of optimal surgical approach and prosthetic implants. Additionally, this technology makes the previously manual operations much faster, accurate and cheaper. The outcome based on literature review and three case studies strongly suggests that RP technology might become part of a standard protocol in the medical sector in the near future. Originality/value – The article is beneficial to study the influence of RP and associated technology in the field of medicine. Keywords Technology, Rapid prototyping, Model, CAD, Computer tomography (CT), Fabrication Paper type General review

1. Introduction

in which suitable RP system uses CAD data to develop the physical model. Nowadays, variety of materials (instead of normal RP material) and some medical-grade materials are available, which can be used to fabricate RP models on the basis of their use in different medical applications. This article covers most commonly available, current RP techniques and their medical applications. The techniques which have mainly been used for fabricating medical models are stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM), three-dimensional printing (3DP) and laminated object manufacturing (LOM). This review article deals with only these RP techniques with their applications and also reports three case studies from literature where RP and associated technology have been successfully used for medical applications.

Rapid prototyping (RP), a layer-by-layer material deposition technique, started during the early 1980s, has significantly improved the ability to fabricate physical models with precise geometries using computer-aided designs (CADs) or data from medical imaging technologies (Melchels et al., 2010). RP is beneficial in the field of medicine, as this technology has the ability to fabricate complex-shaped anatomical parts directly from scanned data such as computerized tomography (CT) images. These models provide a better illustration of the human anatomy, and are used for precise presurgical planning and for assistance in the intensive planning of surgical procedures and also for helping surgeons and medical students to rehearse different surgical procedures realistically (Kai et al., 1998; Liu et al., 2006). RP models can also be used for designing customized implants, prosthesis and function as a communication tool between surgeons and patients (Dhakshyani et al., 2011). RP process can be divided into two phases: virtual (modeling and simulating) and physical (model fabrication) (da Rosa et al., 2004). Before the fabrication of physical models, first comes the virtual phase in which a CAD is prepared by using medical imaging technologies such as CT, magnetic resonance imaging (MRI) and laser digitizing (Ahn et al., 2006; Wang et al., 2010; Willis et al., 2007). The fabrication of the physical model is the second phase, a process

2. RP techniques There are currently a number of RP techniques in the market based on special sintering, layering or deposition methods. Each technique has its own limitations and applications in constructing prototype models. Established RP techniques which are commercially available are summarized in Table I and precisely discussed below. 2.1 Stereolithography The term stereolithography (SLA) was first introduced in 1986 by Charles W. Hull, who defined it as a method based on photo-polymerization of liquid monomer resin for fabricating solid parts. An SLA device typically consists of a vat filled with liquid resin (acrylic or epoxy resin), a movable elevator platform inside the vat, an ultraviolet laser and a

The current issue and full text archive of this journal is available at www.emeraldinsight.com/1355-2546.htm

Rapid Prototyping Journal 20/3 (2014) 256 –267 © Emerald Group Publishing Limited [ISSN 1355-2546] [DOI 10.1108/RPJ-07-2012-0065]

Received: 12 July 2012 Revised: 14 September 2012 Accepted: 11 December 2012

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Table I Features of commercially available RP techniques RP technique (commercially available since)

Process

SLA (1987) SLS (1991) FDM (1991) 3DP (1998) LOM (1990)

Photo-curing Sintering of powders Melt extrusion Ink-jet printing Paper lamination

Layer thickness (␮m)

Accuracy (␮m)

50 76 50-762 177 76-203

⫾ 100 ⫾ 51 ⫾ 127 ⫾ 127 ⫾ 127

Maximum part dimensions (mm3) 500 330 254 355 813

⫻ ⫻ ⫻ ⫻ ⫻

500 380 254 457 559

⫻ ⫻ ⫻ ⫻ ⫻

584 425 254 355 508

Scan speed (mm/s)

Cost (£1000)

N/A 0.001-0.008 380 0.005-0.007 508 (cutting speed)

150-390 250-365 100 Bureau service only 120-235

Source: Pham and Gault (1998); Mousah (2011)

sintered one, and this layer building process is repeated until the whole part is complete (Hur et al., 2001; Pham and Gault, 1998; Yan and Gu, 1997; Yang et al., 2002). The advantage of this technique is the ability to use variety of thermoplastic powders, easy postprocessing and no requirement of support structure. Disadvantages of this method include high costs and the abrasive surface of sintered models (Petzold et al., 1999). SLS is capable of using a wide range of materials for model production including polycarbonate, polyvinyl chloride, acrylonirile butadine styrene (ABS), nylon, resin, polyster, polypropane, polyurethane and investment casting wax. Moreover, this technique is well suited for manufacturing of dental implants (Traini et al., 2008), scaffolds (Leong et al., 2003) and medical devices (Bertol et al., 2010).

platform, as shown in Figure 1. In SLA, the surface layer of resin is cured selectively by the laser beam following the path defined in the slicing model. After creating one layer, the movable platform is lowered into the vat, and then the laser beam tracing process is repeated. This process continues layer by layer until the part fabrication is completed. The advantages of SLA include smooth surface finish and high part building accuracy, whereas disadvantages of this process include time-consuming postprocessing and use of expansive and toxic material (Chockalingam et al., 2008; Guangshen et al., 2009; Wang et al., 1996; Yan and Gu, 1997; Zhou et al., 2000). SLA is well suited for craniomaxillofacial surgery (congenital, system-bound growth disorders and facial craniosynostoses) (Bill et al., 1995; Petzold et al., 1999). This technology (SLA) also has a strong prospective for biomedical applications, such as to manufacture anatomically shaped implants, tailor-made biomedical devices (hearing aids), and has proven to facilitate and speed-up the surgical procedures, especially in implant placements and complex surgeries (Melchels et al., 2010).

2.3 Fused deposition modeling The FDM machine is an XY plotter device which carries an extrusion head. A plastic filament is fed through a heating element, which heats it to a semi-molten state. The filament is then fed through a nozzle and deposited onto a platform to form each layer. The latest FDM system includes two nozzles, one for the part material and one for the support material, as represented in Figure 3. The FDM process uses a variety of modeling materials and colors, such as medical-grade ABS and investment casting wax for model fabrication. FDM advantages include compact construction of the FDM machine, the possibility to sterilize these models and good geometric accuracy; on the other hand, disadvantages include

2.2 Selective laser sintering The SLS process fabricates parts by fusing powdered materials with a CO2 laser instead of liquid. The powdered material is spread by a roller over the work surface and preheated to a temperature slightly lesser than its melting point, and then a laser beam traces the cross-section on the powder surface to heat up the powder to the sintering temperature so that the powder scanned by the laser gets bonded, as illustrated in Figure 2. After completing one layer, the roller spreads another layer of fresh powder over the

Figure 2 Schematic of SLS process

Figure 1 Schematic of SLA process

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Sushant Negi, Suresh Dhiman and Rajesh Kumar Sharma

Volume 20 · Number 3 · 2014 · 256 –267

Figure 3 Schematic of FDM process

complex craniofacial malformations (osteotomies and vector of distraction). 3DP can be performed more quickly (4 hours for a full skull) and easily, and it is also more cost effective when compared with other RP techniques (Cohen et al., 2009; Hoque, 2011). 2.5 Laminated object manufacturing Helisys introduced the LOM, which creates parts from laminated sheets of paper, plastic or metal by a laser, as shown in Figure 5. This technique only requires a cut of the outline of each layer into a sheet of paper using a laser to match a cross-section of the model. After each outline has been cut, the roll of paper is advanced, then a new layer is glued onto the stack and the same process is repeated until the whole part is fabricated, and then some trimming, hand finishing and curing are required. However, material costs are very low. Plastics, composites, ceramics, metals and various organic and inorganic materials with different chemical and mechanical properties for a variety of applications can be processed. LOM is well suited for complex and large parts. The build speed is very fast, but a high effort is needed for decubing, finishing and sealing the parts (Liu et al., 2006; Noorani, 2006).

slow building speed and lower surface quality than SLA (Lee et al., 2005, 2007; Wykes et al., 1999). FDM is well suited for the fabrication of bone models, as it uses build materials that produce hard, robust models and also can produce complex shape models, surgical guides and templates (Liu et al., 2006). 2.4 3D printing Soildscapes introduced 3DP technology that uses dual-ink printer heads to deposit both thermoplastic part material and a wax support structure. The devices use a milling operation after fabricating each layer to create a very thin and precise layer, as presented in Figure 4. Once a layer is deposited, the piston that supports the powder bed and the part lowers so that the next powder layer can be spread and selectively joined. This layer-by-layer process repeats until the whole part is fabricated (Lee et al., 2007; Liu et al., 2006; Noorani, 2006). 3DP allows the fabrication of complex geometrical shapes, e.g. hanging partitions inside cavities, without artificial support structures. After taking the CT scan, the rendering of the DICOM data and transformation into standard tessellation language (STL) format takes a maximum of a half an hour, and the printing process and infiltration take approximately 4-6 hours (Hoque, 2011). 3DP’s advantages over other techniques include good fabrication speed and low materials cost. Disadvantages include surface finish, moderate strength, hand-free post processing and availability of materials (Liu et al., 2006). 3DP technology is a reliable method for assisting in precise mandibular reconstruction using bone plates and bone grafts, and these models have also been used for planning distraction osteogenesis related to

2.6 Materials In the case of medical applications, the RP models can be fabricated with a variety of materials, and the selection of material depends on the purpose of fabrication. However, some medical applications (surgical tools or medical implants) require models which have the ability to be sterilized or remain compatible with human tissue-like biomaterials. A biomaterial can be classified as any material used to manufacture devices that replace a part or a function of the body in a safe and reliable way. Metallic biomaterials are mainly used in areas of high static or cyclic stress and are well suited for medical implants such as cranial plates and acetabular implants. Ceramic materials are typically solid inert compounds and are used where resistance to wear is of primary importance, such as dental implants and crowns, whereas medical-grade polymers are used in various medical applications where stability, flexibility and controlled porosity are demanded, such as tissue repair, drug delivery devices and medical implants (Brennan, 2010). Some categorized biomaterials for medical use are shown in Table II.

3. RP model fabrication RP machine needs CAD information to fabricate a physical model, so for that purpose RP process can be divided into two phases: virtual and physical. As mentioned earlier, first comes the virtual phase, which consists of using image processing tools that involve data acquisition and image processing, to create a virtual model through dynamic and interactive simulation. The fabrication of the physical model is the second phase (physical). Data acquisition is the process in which high-resolution images of human anatomy are captured by using medical imaging technologies such as CT, MRI and others. After data acquisition, images are processed by suitable software tools, then the output (virtual model) is transferred in the STL file format to the RP system for fabricating a physical part, called a medical model (Starly et al., 2005). The

Figure 4 Schematic of 3D printing process

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Figure 5 Schematic of LOM process

Table II Categorized biomaterials for medical applications Metals

Ceramics

316L stainless steel Alumina Titanium alloys Cobalt chromium alloys Ti6Al4V

Zirconia Carbon

(Milovanovic and Trajanovic, 2007). Most commonly, CT, MRI and laser digitizing techniques are used for this purpose, others are cone beam tomography, X-ray, ultrasound and others (Abbott et al., 1998; Chang et al., 1991; Lambrecht et al., 2009; Liu et al., 2006; Meakin et al., 2004; Schievano et al., 2010). It provides important scanned data of anatomical structure for diagnostic reasons, and same data can be used to obtain geometrical information of the body structures for 3D modeling. Some of the most commonly used medical imaging techniques are described in the following section.

Polymers Ultra-high molecular weight polyethylene Polyurethane

Hydroxyapatite Calcium phosphate

Source: Brennan (2010); Mour (2010); Vail et al. (1999)

3.1.1 Computerized tomography CT is a medical imaging technique that uses computerprocessed X-rays to scan a slice of tissue from multiple directions for generating tomography images of specific areas of the body. The absorption of different tissues is calculated and displayed according to grey-scale values on a screen. The resolution of CT data can be increased by decreasing the slice thickness, producing more slices along the same scanned region, and resolution of approximately 1 mm can be achieved in most practical cases. It is very suitable for hard tissues and bony structures such as cortical and trabecular bones, which are assessed less with MRI technique (Liu et al., 2006). Nowadays, the speed at which CT scans are obtained has increased much more – the new system of CT scanners can create a slice in about a second (Noorani, 2006). The technology known as spiral CT allows for shorter scanning time and small slice intervals with respect to old scanners (Hoque, 2011).

complete process of medical model fabrication is illustrated in Figure 6. 3.1 Data acquisition Data acquisition is a process of capturing the threedimensional (3D) shape of an existing part by using contact and non-contact measuring devices; only non-contact methods (medical imaging technologies) are considered here. Medical imaging technologies are generally used to visualize the configurations of bones, organs and tissues, but they also have the ability to export scanned image data and additional information in commonly known medical file format, such as digital imaging and communications in medicine (DICOM) (Berce et al., 2005; Rengier et al., 2010), and finally make it possible to convert scanned image data from DICOM to STL file format, which is a universally accepted RP file format 259

Basics and applications of rapid prototyping medical models

Rapid Prototyping Journal

Sushant Negi, Suresh Dhiman and Rajesh Kumar Sharma

Volume 20 · Number 3 · 2014 · 256 –267

Figure 6 General process of RP model production for medical applications

3.1.2 Magnetic resonance imaging MRI makes use of the property of nuclear magnetic resonance to image nuclei of atoms inside the body for detecting different tissue characteristics, especially soft tissues. MRI technique does not use X-ray radiation, and it has the ability to provide scans of nearly any planar orientation without surgical intervention. MRI is safe for most patients, but those who have implanted medical devices such as heart pacemakers, cochlear implants may not be able to have an MRI (Noorani, 2006). An MRI scanner uses a strong magnetic field, which causes protons to align parallel or anti-parallel to it and measure the density of a specific nucleus, normally hydrogen nucleus. The speed at which protons lose their magnetic energy is different in different tissues; therefore, it allows detailed representation of the region of interest. MRI provides good contrast between the different soft tissues of the body, which makes it especially useful in imaging the brain, muscles and central nervous system with respect to other medical imaging techniques such as CT or X-rays. MRI slice thickness is limited to 0.5 mm at the highest resolution, and measurement system is volumetric (Hoque, 2011; Liu et al., 2006).

3.2 Image processing Images of the body are taken in thin cross-sectional “slices” which can then be layered by using commercial available software like MIMICS, 3D Doctor and Voxim to create a 3D model of anatomical parts. These software systems performs the necessary segmentation of the anatomy through sophisticated 3D selection and editing tools and provides the interface between scanned data of CT, MRI or technical scanners and RP systems (Noorani, 2006). These software systems allow modification of the images by defining various tissue densities for display, to select the regions of interest from the general information available from the scanner. It enables the surgeons and radiologists to control and select the correct segmentation of CTs or MRIs. After completing the segmentation and visualization, the data are converted to STL format. This format is compatible with most commonly used RP machines (Gibson et al., 2006; Liu et al., 2006; Tukuru et al., 2008). 3.3 Model fabrication This step includes choosing the right RP technique according to the demand of medical application. As we know, every RP system has its strength and weaknesses, and so a suitable RP system or technique needs to be chosen to fulfill various requirements of a medical application like accuracy, surface finish, cost, visual appearance of internal structures, number of desired colors in the model, strength, availability of materials and mechanical properties. Then finally, 3D virtual model in STL file format is transferred to the RP system and building starts. After the fabrication of model, it needs to be evaluated and validated by the team and, in particular, by surgeons, so as to ensure that it is accurate and serves the purpose (Milovanovic and Trajanovic, 2007). Furthermore, depending on the use of the model, it can be sterilized for assistance in an operating theater (Petzold et al., 1999).

3.1.3 Laser digitizing Laser digitizing is a medical imaging technique that uses a laser probe which emits a diode-based laser beam, which forms profiles on the surface of the anatomy being scanned. Each profile is collected as a polyline entity, and the combination of profiles yields a 3D volume (Hoque, 2011). This technique allows acquisition only of external data, such as in dental applications where only external data are required, whereas CT and MRI comprise both internal and external data. By obtaining only external data, it reduces the scanning time, file size and processing time to convert scanned data to CAD data. This method also has the advantage of not emitting any radiation (Liu et al., 2006). 260

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Volume 20 · Number 3 · 2014 · 256 –267

4. Use of RP models in medical applications

a reasonable cost (Balazic and Kopac, 2007). This technology allows the physicians to create accurate implants for their patients rather than the use of standard-sized implants, such as dental implants, hip sockets, knee joints and spinal implants, which could greatly benefit the patients (Milovanovic and Trajanovic, 2007). Using RP, surgical implants have become more precise, surgery time and risk of surgical complication has been significantly reduced and to make customized implants it is an alternative to standard implants (Liu et al., 2006; Noorani, 2006).

RP has been recently introduced in the field of medicine when compared to its long-standing use in various engineering applications, and so numerous researchers have reported the influence of RP technology in various areas of medical field. Some of the areas in which RP technology has been successfully used are discussed below. 4.1 Surgical planning RP has proven to be beneficial to surgical planning, as the these models provide the physician and surgical team a visual aid that can be used to better plan a surgery, to study the bone structure of patient before the surgery, to decrease surgery time and risk during surgery as well as costs, to predict problem cause during operation and to facilitate the diagnostic quality. These RP models can be used to rehearse complex procedures and to better understand the complex anomaly; therefore, these models are especially beneficial in surgeries where there are anatomical abnormalities and deformities (Kai et al., 1998; Liu et al., 2006). Some studies in heart surgery (Sodian et al., 2007), spine surgery (Guarino et al., 2007; Mizutani et al., 2008; Paiva, 2007), craniofacial and maxillofacial surgery (Faber et al., 2006; Maravelakis et al., 2008; Mehra et al., 2011; Peltola et al., 2012; Poukens et al., 2003; Zenha et al., 2011) and hip surgery (Dhakshyani et al., 2012; Monahan and Shimada, 2007) have shown the potential and benefit of RP models in the field of surgery and reported a significant improvement in diagnosis. In addition, surgeons estimated that the use of RP models reduced operating time by a mean of 17.63 per cent (D’urso et al., 1999).

4.5 Scaffoldings and tissue engineering RP techniques are very much suitable for generating implants with special geometrical characteristics, such as scaffolds for the restoration of tissues, and serve as an alternative to conventional scaffold fabrication methods (Hutmacher et al., 2004). Scaffolds are porous supporting structures, serve as an adhesion substrate for the cells and provide temporary mechanical support and guidance to the growing tissue in damaged or defective bones of the patient (Kim and Mooney, 1998; Yeong et al., 2004). RP techniques like SLS, 3DP and FDM have proved to be suitable for fabricating controlled porous structures through the use of biomaterials and it has significantly contributed in the field of scaffolding and tissue engineering. RP technology has increased the ability to create complex geometries, customized products and provide high accuracy features, as well as enhance the possibilities to control pore size and distribution of pores within the scaffold (Peltola et al., 2008). 4.6 Prosthetics and orthotics RP has proven to be beneficial to the fields of prosthetics and orthotics, as it starts with specific patient anatomy. The patient’s specific alignment characteristics are included in the model, allowing for development of a biomechanically correct geometry that improves the fit, comfort and stability (Noorani, 2006). There are always patients outside the standard range, between sizes or with special requirements caused by disease or genetics. With the aid of RP, it becomes possible to manufacture a custom prosthesis that precisely fits a patient at reasonable cost; e.g. patterns for dental crowns and implant structures can be fabricated using an RP machine (Liu et al., 2006).

4.2 Medical education and training RP models provide a better demonstration of external and internal structures of human anatomy, and they can be made in many colors so these models can be used as teaching aids in research, medical education and in museums for educational and display purposes. RP models can be distributed in kits to schools and museums for a better illustration of anatomy and medical training purposes. Furthermore, these models can be used by medical students or young doctors to better understand the problems or surgical procedures without causing discomfort to the patient (Liu et al., 2006; Mori et al., 2009; Nyaluke et al., 1995).

4.7 Mechanical bone replicas RP can be used for the fabrication of mechanical bone replicas. With the aid of RP, it becomes easy to replicate the material variations and mechanical characteristics within a bone. A composite structure built with a lattice structure of SLA can create two distinct regions that have properties similar to cortical and trabecular bones. These replicas of bones can be used to observe the bone strength under different conditions. Additionally, it can be beneficial to recreate events, and the stresses, fractures and other changes in the bone can be observed, which would definitely help the doctors and researchers (Noorani, 2006; www.rpc.msoe.edu/medical).

4.3 Design and development of medical devices and instrumentation Another application of RP is in fabricating medical devices and instrumentations. RP techniques can be used to design, develop and manufacture medical devices and instruments. It includes dental devices, hearing aids and surgical aid tools (Noort, 2012). 4.4 Customized implant design RP technology is very much able to fabricate customized implants and fixtures due to the inherent strength of this technology to fabricate complex geometry within a very short time. The combination of medical imaging technologies, RP and CAD packages makes it possible to manufacture customized implants and fixtures that precisely fit a patient at

4.8 Forensics RP can be a beneficial tool in criminal investigation, especially in homicide cases, where it is very important to reconstruct the crime scene for investigation. RP models can be kept as 261

Basics and applications of rapid prototyping medical models

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Volume 20 · Number 3 · 2014 · 256 –267

evidence in criminal investigation and will help investigators find answers to some questions. In many cases, the ability to reconstruct scenes and events accurately would help forensic experts to understand and solve the cases more quickly. These models are accurate enough to see the effects of wounds and allow for accurate predictions of the forces, implements and other key events can be determined using these models. Especially, in the case of a surviving victim with a difficultto-access wound, e.g. for the skull, a model can be used for detailed analysis. Using RP models, scenes can be re-created in the court room, and it can help prosecutors to throw some light on what really happened (Liu et al., 2006; www. rpc.msoe.edu/medical).

1

4.9 Anthropology This is an another application where RP technology can be very beneficial to anthropologists because replication of delicate bones, teeth and other artifacts can be made so that molding, measuring and dissecting of the remains can be performed without causing harm to the original finding. Especially in cases where only one or two specimens exist, research can be done on built models without harming the original or rare specimen. The models that are built can also be used to show changes in evolution that have taken place over vast periods (Noorani, 2006; www.rpc.msoe.edu/medical).

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2

3

5

tomography images of deficient and contralateral ears with the help of finer CT scanning (0.63-mm slice thickness); reconstruction of the corresponding 3D models in which the correct geometry and position of the prosthesis were ensured by stacking the CT scan images of the contralateral normal ear in reverse order, and joining them using medical modeling software, MIMICS (Materialise, Belgium); design of the final model of missing ear (prosthesis) was obtained by subtracting the CAD model of the remnant portion of the defective ear from the CAD model of the mirrored contralateral ear using a haptic CAD system (FreeForm, SensAble Technologies, USA); fabrication of prosthesis master using a suitable RP system (FDM), the dimensions of fabricated model was measured as per the standards (standard auricular morphological measurement) and compared with the original CAD model to determine the accuracy (dimensional error) then finally; the fabrication of the final prosthesis using a mould made from the master (FDM model) in which medical-grade silicone rubber of the appropriate color was packed into the mold to fabricate the final ear prosthesis.

The final fabricated prosthesis was also measured as per standards, and percentage difference was calculated with respect to the CAD model and then successfully fitted to the deficient side of the patient using medical-grade adhesive. The prosthesis may change its color or deteriorate over time, and may require replacement in future. This can be facilitated by the availability of the digital model of the prosthesis. The postoperative appearance showed the excellent result in terms of aesthetics. Researchers concluded that the use of RP and associated technology provided a high degree of accuracy in terms of shape, size and position of the prosthesis. It enabled accurate reproduction of customized prosthesis without requiring sculpting skills and was much faster than the conventional (manual) method.

5. Case reports In this section, three case reports from open literature have been considered for discussion, which present different specific applications of RP in the field of medicine. Case 1: Customized prosthesis implant Researchers (Subburaj et al., 2007) in the Department of Mechanical Engineering [Indian Institute Of Technology (IIT), Mumbai] and Department of Prosthodontics (Government Dental College and Hospital, Mumbai) considered a patient (male, 19 years) with congenital absence of the right ear for investigation, as presented in Figure 7. The purpose was to use CAD and RP technologies for the rapid development of auricular prosthesis and demonstrated a real-life case study. The anatomic morphology of the prosthesis, matching the morphology of the contralateral ear, was obtained by following these five steps:

Case 2: Preoperative planning Report of two cases (female patients of age 23 and 18 years with cubitus deformity) as shown in Figure 8 are presented by

Figure 7 A patient (male, 19 years) with congenital absence of the right ear

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Figure 8 A patient (female, 18 years) with cubitus varus of left elbow

Figure 9 (a) STL design file for the porous scaffold; (b) PCL scaffold fabricated by SLS

a group of researchers (Mahaisavariya et al., 2006) in which they reported some work on surgical planning of corrective osteotomy for cubitus varus using RP models. First of all, a CT scan was performed on both the deformed and the normal elbow using a Philip spiral CT scanner (Thomoscan, AV), CT scan acquisition was performed with 2-mm slice thickness and reconstruction was performed with 1-mm slice thickness; these scanned data were used to construct a 3D CAD model using medical imaging and digital CAD software (MIMICS and Magics RP; Materialise, NV Belgium), and surgical planning of corrective osteotomy was virtually planned and simulated in the 3D CAD model. The proper location of osteotomy, the amount of wedging bone and the tilting of the plane for osteotomy cut were measured by performing 3D evaluation of the deformed and mirrored normal humerus on screen. After calculating and determining the optimal configuration, the data of deformed and normal humerus were used to fabricate RP models using 3D printing machine (Z Corp Inc.). These RP models were used by surgeons to rehearse the osteotomy before a real surgery. Both patients were successfully operated as per the preoperative planning on the RP models, and showed excellent postoperative results in terms of cosmetic and functional result. This case study clearly shows that RP and associated technology (CT) can facilitate surgeons in preoperative planning for certain complex cases like osteotomy of complex deformity of hip, pelvis and spine, and allows the surgeons to choose proper configuration and the most appropriate location of osteotomy according to individual patient need.

which is seeded with cells or nutrients and provides necessary support and shape to growing tissue (Armillotta and Pelzer, 2008). Researchers (Williams et al., 2005) at the University of Michigan have explored the potential of SLS (an RP technique) to fabricate polycaprolactone (PCL) scaffolds, as presented in Figure 9. PCL is a bioresorbable polymer which has sufficient mechanical properties for bone tissue engineering applications. Furthermore, researchers evaluated the biological properties of these SLS-manufactured scaffolds by seeding with bone morphogenetic protein-7-transduced human fibroblasts and evaluated the growth of generated tissue. They found that SLS-fabricated scaffolds matched the design well, had mechanical strength within the range of trabecular bone and supported the growth of tissue. It is concluded that PCL scaffolds fabricated by SLS have great potential for the replacement of skelton tissue in the field of tissue engineering.

Case 3: Tissue engineering RP has been used as an alternative to conventional scaffold fabrication methods within the tissue engineering field. Tissue engineering is the process of growing the relevant cell(s) in vitro into required 3D organ or tissue (Ciocca et al., 2009; Sachlos and Czernuszka, 2003). This method has been used for the repair of damaged tissue and organs. The main element for cell structure is scaffold, a prefabricated porous structure

6. Conclusions RP is making a significant effect in the field of medicine with a variety of medical applications, and its potential has also been demonstrated in several studies (Dhakshyani et al., 2012; Esses et al., 2011; Mao et al., 2010; Sanghera et al., 2001). A prospective trial (45 patients with craniofacial, maxillofacial 263

Basics and applications of rapid prototyping medical models

Rapid Prototyping Journal

Sushant Negi, Suresh Dhiman and Rajesh Kumar Sharma

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and skull base cervical spinal pathology were selected) with the objective of assessing the utility of 3D models in complex surgery performed by researchers (D’urso et al., 1999) concluded that these models significantly improved the quality of preoperative planning and diagnosis, reduced operative time and risk, enhanced team communication and assisted the patients to better understand their pathology. Another study of 47 complex mandibular reconstruction cases (between 2003 and 2009) concluded that 95.7 per cent of the patients were found to have at least a satisfactory result and the majority (38 out of 47) of patients were in good and very good end result categories (Zenha et al., 2011). Additionally, this technology makes the previously manual operations much faster, accurate and cheaper (Noort, 2012). The outcome based on literature review and three case studies strongly suggests that RP technology might become part of standard protocol in medical sector in the near future. However, presently this technology cannot be used in daily clinical practices due to some issues such as suitable material, time and high cost of the procedure. Therefore, these issues restrict the utilization of RP in complex cases where considerable cost savings and quality benefits are generally expected (Giannatsis and Dedoussis, 2009). Furthermore, this technology can be used as an alternative to conventional fabrication methods within the field of tissue engineering (Leong et al., 2003), customize implants (Noort, 2012; Traini et al., 2008) and medical devices (Bertol et al., 2010). Further research is required to reduce the overall cost (virtual planning and fabrication cost) of RP technology, for the development of suitable biomaterials and for the development of RP systems designed specifically for medical applications.

Journal of Oral and Maxillofacial Surgery, Vol. 24 No. 1, pp. 98-103. Brennan, J. (2010), “Production of anatomical models from CT scan data”, Masters Dissertation, De Montfort University, Leicester. Chang, L.W., Chen, H.W. and Ho, J.R. (1991), “Reconstruction of 3D medical images: a nonlinear interpolation technique for reconstruction of 3D medical images”, Graphical Models and Image Processing, Vol. 53 No. 4, pp. 382-391. Chockalingam, K., Jawahara, N., Chandrasekarb, U. and Ramanathana, K.N. (2008), “Establishment of process model for part strength in stereolithography”, Journal of Materials Processing Technology, Vol. 208 No. 1-3, pp. 348-365. Chua, C.K., Leong, K.F. and Lim, C.S. (2003), Rapid Prototyping: Principles and Applications, World Scientific Publishing Company, Toh Tuck Link. Ciocca, L., Crescenzio, F.D., Fantini, M. and Scotti, R. (2009), “CAD/CAM and rapid prototyped scaffold construction for bone regenerative medicine and surgical transfer of virtual planning: a pilot study”, Computerized Medical Imaging and Graphics, Vol. 33 No. 1, pp. 58-62. Cohen, A., Laviv, A., Berman, P., Nashef, R. and Abu, T.J. (2009), “Mandibular reconstruction using stereolithographic 3-dimensional printing modeling technology”, Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, Vol. 108 No. 5, pp. 661-666. da Rosa, E.L., Oleskovicz, C.F. and Aragao, B.N. (2004), “Rapid prototyping in maxillofacial surgery and traumatology: case report”, Brazilian Dental Journal, Vol. 15 No. 3, pp. 243-247. Dhakshyani, R., Nukman, Y. and Abu Osman, A.N. (2012), “Rapid prototyping models for dysplastic hip surgeries in Malaysia”, European Journal of Orthopaedic Surgery and Traumatology, Vol. 22 No. 1, pp. 41-46. Dhakshyani, R., Nukman, Y., Abu Osman, A.N. and Vijay, C. (2011), “Preliminary report: rapid prototyping models for dysplastic hip surgery”, Central European Journal of Medicine, Vol. 6 No. 3, pp. 266-270. D’urso, P.S., Barker, T.M., Earwaker, W.J., Bruce, L.J., Atkinson, R.L., Lanigan, M.W., Arvier, J.F. and Effeney, D.J. (1999), “Stereolithographic biomodelling in craniomaxillofacial surgery: a prospective trial”, Journal of Cranio-Maxillofacial Surgery, Vol. 27 No. 1, pp. 30-37. Esses, S.J., Berman, P., Bloom, A.I. and Sosna, J. (2011), “Clinical applications of physical 3D models derived from MDCT data and created by rapid prototyping”, American Journal of Roentgenology, Vol. 196 No. 6, pp. W683-W688. Faber, J., Berto, P.M. and Quaresma, M. (2006), “Rapid prototyping as a tool for diagnosis and treatment planning for maxillary canine impaction”, American Journal of Orthodontics and Dentofacial Orthopedics, Vol. 129 No. 4, pp. 583-589. Giannatsis, J. and Dedoussis, V. (2009), “Additive fabrication technologies applied to medicine and health care: a review”, International Journal of Advanced Manufacturing Technology, Vol. 40 No. 1-2, pp. 116-127. Gibson, I., Cheung, L.K., Chow, S.P., Cheung, W.L., Beh, S.L., Savalani, M. and Lee, S.H. (2006), “The use of

References Abbott, J.R., Netherway, D.J., Wingate, P.G., Abbott, A.H., David, D.J., Trott, J.A. and Yuen, T. (1998), “Computer generated mandibular model: surgical role”, Australian Dental Journal, Vol. 43 No. 6, pp. 373-378. Ahn, D.G., Lee, J.Y. and Yang, D.Y. (2006), “Rapid prototyping and reverse engineering applccation for orthopedic surgery planning”, Journal of Mechanical Science and Technology, Vol. 20 No. 1, pp. 19-128. Armillotta, A. and Pelzer, R. (2008), “Modeling of porous structures for rapid prototyping of tissue engineering scaffolds”, International Journal of Advanced Manufacturing Technology, Vol. 39 No. 5-6, pp. 501-511. Balazic, M. and Kopac, J. (2007), “Improvements of medical implants based on modern materials and new technologies”, Journal of Achievements in Materials and Manufacturing Engineering, Vol. 25 No. 2, pp. 31-34. Berce, P., Chezan, H. and Balc, N. (2005), “The application of rapid prototyping technologies for manufacturing the custom implants”, Proceedings of the ESAFORM conference in Cluj-Napoca, Romania, 2005, pp. 679-682. Bertol, L.S., Junior, W.K., Silva, F.P. and Kopp, C.A. (2010), “Medical design: direct metal laser sintering of Ti– 6Al– 4V”, Materials and Design, Vol. 31 No. 8, pp. 3982-3988. Bill, J.S., Reuther, J.F., Dittmann, W., Kubler, N., Meier, J.L., Pistner, H. and Wittenberg, G. (1995), “Stereolithography in oral and maxillofacial operation planning”, International 264

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rapid prototyping to assist medical applications”, Rapid Prototyping Journal, Vol. 12 No. 1, pp. 53-58. Guangshen, X., Jing, J., Sheng, L., Ronghua, Q. and Huan, P. (2009), “Research on optimizing build parameters for stereolithography technology”, in Proceedings of 2009 International Conference on Measuring Technology and Mechatronics Automation Conference, ICMTMA 2009, IEEE Computer Society, Los Alamos, CA, pp. 883-886. Guarino, J., Tennyson, S., McCain, G., Bond, L., Shea, K. and King, H. (2007), “Rapid prototyping technology for surgeries of the pediatric spine and pelvis: benefits analysis”, Journal of Pediatric Orthopaedics, Vol. 27 No. 8, pp. 955-960. Hoque, M.E. (2011), Advanced Applications of Rapid Prototyping Technology in Modern Engineering, InTech, Rijeka. Hur, S.M., Choi, K.H., Lee, S.H. and Chang, P.K. (2001), “Determination of fabricating orientation and packing in SLS process”, Journal of Material Processing Technology, Vol. 112 No. 2-3, pp. 236-243. Hutmacher, D.W., Sittinger, M. and Risbud, M.V. (2004), “Scaffold-based tissue engineering rationale for computer-aided design and solid free-form fabrication systems”, Trends in Biotechnology, Vol. 22 No. 7, pp. 354-362. Kai, C.C., Meng, C.S., Ching, L.S., Hoe, E.K. and Fah, L.K. (1998), “Rapid prototyping assisted surgery planning”, International Journal of Advanced Manufacturing Technology, Vol. 14 No. 9, pp. 624-630. Kim, B.S. and Mooney, D.J. (1998), “Development of biocompatible synthetic extracellular matrices for tissue engineering”, Trends in Biotechnology, Vol. 6 No. 5, pp. 224-230. Lambrecht, J.T., Berndt, D.C., Schumacher, R. and Zehnder, M. (2009), “Generation of three-dimensional prototype models based on cone beam computed tomography”, International Journal of Computer Assisted Radiology and Surgery, Vol. 4 No. 2, pp. 175-180. Lee, B.H., Abdullah, J. and Khan, Z.A. (2005), “Optimization of rapid prototyping parameters for production of flexible ABS object”, Journal of Materials Processing Technology, Vol. 169 No. 1, pp. 54-61. Lee, C.S., Kim, S.G., Kim, H.J. and Ahn, S.H. (2007), “Measurement of anisotropic compressive strength of rapid prototyping parts”, Journal of Materials Processing Technology, Vol. 187-188, pp. 627-630. Leong, K.F., Cheah, C.M. and Chua, C.K. (2003), “Solid freeform fabrication of three-dimensional scaffolds for engineering replacement tissues and organs”, Biomaterials, Vol. 24 No. 13, pp. 2363-2378. Liu, Q., Leu, M.C. and Schmitt, S.M. (2006), “Rapid prototyping in dentistry: technology and application”, International Journal of Advanced Manufacturing Technology, Vol. 29 No. 3-4, pp. 317-335. Mahaisavariya, B., Sitthiseripratip, K., Oris, P. and Tongdee, T. (2006), “Rapid prototyping model for surgical planning of corrective osteotomy for cubitus varus: report of two cases”, Injury Extra, Vol. 37 No. 5, pp. 176-180. Mao, K., Wang, Y., Xiao, S., Liu, Z., Zhang, Y., Zhang, X., Wang, Z., Lu, N., Shourong, Z., Xifeng, Z., Geng, C. and Baowei, L. (2010), “Clinical application of computer-

designed polystyrene models in complex severe spinal deformities: a pilot study”, European Spine Journal, Vol. 19 No. 5, pp. 797-802. Maravelakis, E., David, K., Antoniadis, A., Manios, A., Bilalis, N. and Papaharilaou, Y. (2008), “Reverse engineering techniques for cranioplasty: a case study”, Journal of Medical Engineering and Technology, Vol. 32 No. 2, pp. 115-121. Meakin, J.R., Shepherd, D.E.T. and Hukins, D.W.L. (2004), “Fused deposition models from CT scans”, British Journal of Radiology, Vol. 77 No. 918, pp. 504-507. Mehra, P., Miner, J., D’Innocenzo, R. and Nadershah, M. (2011), “Use of 3-D stereolithographic models in oral and maxillofacial surgery”, Journal of Oral and Maxillofacial Surgery, Vol. 10 No. 1, pp. 6-13. Melchels, F., Feijen, J. and Grijpma, D.W. (2010), “A review on stereolithography and its applications in biomedical engineering”, Biomaterials, Vol. 31 No. 24, pp. 6121-6120. Milovanovic, J. and Trajanovic, M. (2007), “Medical applications of rapid prototyping”, Mechanical Engineering, Vol. 5 No. 1, pp. 79-85. Mizutani, J., Matsubara, T., Fukuoka, M., Tanaka, N., Iguchi, H., Furuya, A., Okamoto, H., Wada, I. and Otsuka, T. (2008), “Application of full-scale three-dimensional models in patients with rheumatoid cervical spine”, European Spine Journal, Vol. 17 No. 5, pp. 644-649. Monahan, M. and Shimada, K. (2007), “A study of user performance employing a computer-aided navigation system for arthroscopic hip surgery”, International Journal of Computer Assisted Radiology and Surgery, Vol. 2 No. 3-4, pp. 245-252. Mori, K., Yamamoto, T., Oyama, K. and Nakao, Y. (2009), “Modification of three-dimensional prototype temporal bone model for training in skull-base surgery”, Neurosurgery, Vol. 32 No. 2, pp. 233-239. Mour, M., Das, D., Winkler, T., Hoenig, E., Mielke, G., Morlock, M.M. and Schilling, A.F. (2010), “Advances in porous biomaterials for dental and orthopaedic applications”, Materials, Vol. 3 No. 5, pp. 2947-2974. Mousah, A.A. (2011), “Effects of filler content and coupling agents on the mechanical properties and geometrical accuracy of selective laser sintered parts in glass bead-filled polyamide 12 composites”, PhD thesis, Cardiff University, Cardiff. Noorani, R. (2006), Rapid Prototyping: Principles and Applications, John Wiley and Sons, Inc, Hoboken, NJ. Noort, R.V. (2012), “The future of dental devices is digital”, Dental Materials, Vol. 28 No. 1, pp. 3-12. Nyaluke, A.P., An, D., Leep, H.R. and Parsaei, H.R. (1995), “Rapid prototyping: applications in academic institutions and industry”, Computers and Industrial Engineering, Vol. 29 No. 1-4, pp. 345-349. Paiva, W.S. (2007), “Application of the steriolithography technique in complex spine surgery”, Arquivos de Neuro-Psiquiatria, Vol. 65 No. 2B, pp. 443-445. Peltola, M.J., Vallittu, P.K., Vuorinen, V., Aho, A.A.J., Puntala, A. and Aitasalo, K.M.J. (2012), “Novel composite implant in craniofacial bone reconstruction”, European Archives of Oto-Rhino-Laryngology, Vol. 269 No. 2, pp. 623-628. 265

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Peltola, S.M., Grijpma, D.W., Melchels, F.P.W. and Kellomäki, M. (2008), “A review of rapid prototyping techniques for tissue engineering purposes”, Annals of Medicine, Vol. 40 No. 4, pp. 268-280. Petzold, R., Zeilhofer, H.F. and Kalender, W.A. (1999), “Rapid prototyping technology in medicine: basics and applications”, Computerized Medical Imaging and Graphics, Vol. 23 No. 5, pp. 277-284. Pham, D.T. and Gault, R.S. (1998), “A comparison of rapid prototyping technologies”, International Journal of Machine Tools and Manufacture, Vol. 38 No. 10-11, pp. 1257-1287. Poukens, J., Haex, J. and Riediger, D. (2003), “The use of rapid prototyping in the preoperative planning of distraction osteogenesis of the cranio-maxillofacial skeleton”, International Society for Computer Aided Surgery, Vol. 8 No. 3, pp. 146-154. Rengier, F., Mehndiratta, A., Von Tengg-Kobligk, H., Zechmann, C.M., Unterhinninghofen, R., Kauczor, H.H. and Giesel, F.L. (2010), “3D printing based on imaging data: review of medical applications”, International Journal of Computer Assisted Radiology and Surgery, Vol. 5 No. 4, pp. 335-341. Sachlos, E. and Czernuszka, J.T. (2003), “Making tissue engineering scaffolds work. review on the applications of solid freeform fabrication technology to the production of tissue engineering scaffolds”, European cells and materials, Vol. 5 No. 5, pp. 29-40. Sanghera, B., Naique, S., Papaharilaou, Y. and Amis, A. (2001), “Preliminary study of rapid prototype medical models”, Rapid Prototyping Journal, Vol. 7, pp. 275-284. Schievano, S., Sebire, N.J., Robertson, N.J., Taylor, A.M. and Thayyil, S. (2010), “Reconstruction of fetal and infant anatomy using rapid prototyping of post-mortem MR images”, Insights Imaging, Vol. 1 No. 4, pp. 281-286. Silva, D.N., Gerhardt De Oliverias, D., Meurer, E., Meurer, M.I., Lopes Da Silva, J.V. and Santa Barbara, A. (2008), “Dimensional error in selective laser sintering and 3D-printing of models for craniomaxillary anatomy reconstruction”, Journal of Cranio-Maxillofacial Surgery, Vol. 36 No. 8, pp. 443-449. Sodian, R., Weber, S., Markert, M., Rassoulian, D., Kaczmarek, I., Lueth, T.C., Reichart, B. and Daebritz, S. (2007), “Stereolithographic models for surgical planning in congenital heart surgery”, Annals of Thoracic Surgery, Vol. 83 No. 5, pp. 1854-1857. Song, J.L., Li, Y.T., Deng, Q.L. and Hu, D.J. (2007), “Rapid prototyping manufacturing of silica sand patterns based on selective laser sintering”, Journal of Materials Processing Technology, Vol. 187-188, pp. 614-618. Starly, B., Fang, Z., Sun, W., Shokoufandeh, A. and Regli, W. (2005), “Three dimensional reconstruction for medical-CAD modeling”, Computer Aided Design and Applications, Vol. 2 No. 1-4, pp. 431-438. Subburaj, K., Nair, C., Rajesh, S., Meshram, S.M. and Ravi, B. (2007), “Rapid development of auricular prosthesis using CAD and rapid prototyping technologies”, International Journal of Oral and Maxillofacial Surgery, Vol. 36 No. 10, pp. 938-943. Traini, T., Manganob, C., Sammonsc, R.L., Manganod, F., Macchib, A. and Piattelli, A. (2008), “Direct laser metal

sintering as a new approach to fabrication of an isoelastic functionally graded material for manufacture of porous titanium dental implants”, Dental Materials, Vol. 24 No. 11, pp. 1525-1533. Tukuru, N., Gowda, S.K.P., Ahmed, S.M. and Badami, S. (2008), “Rapid prototype technique in medical field”, Research Journal of Pharmacy and Technology, Vol. 1 No. 4, pp. 341-344. Vail, N.K., Swain, L.D., Fox, W.C., Aufdlemorte, T.B., Lee, G. and Barlow, J.W. (1999), “Materials for biomedical applications”, Materials and Design, Vol. 20 No. 2-3, pp. 123-132. Wang, C.S., Wang, W.H.A. and Lin, M.C. (2010), “STL rapid prototyping bio-CAD model for CT medical image segmentation”, Computers in Industry, Vol. 61 No. 3, pp. 187-197. Wang, W.L., Cheah, C.M., Fuh, J.Y.H. and Lu, L. (1996), “Influence of process parameters on stereolithography part shrinkage”, Materials and Design, Vol. 17 No. 4, pp. 205-213. Williams, J.M., Adewunmib, A., Scheka, R.M., Flanagana, C.L., Krebsbacha, P.H., Feinbergd, S.E., Hollistera, S.J. and Das, S. (2005), “Bone tissue engineering using polycaprolactone scaffolds fabricated via selective laser sintering”, Biomaterials, Vol. 26 No. 23, pp. 4817-4827. Willis, A., Speicher, J. and Cooper, D.B. (2007), “Rapid prototyping 3D objects from scanned measurement data”, Image and Vision Computing, Vol. 25 No. 7, pp. 1174-1184. Wykes, C., Buckberry, C., Dale, M., Reeves, M. and Towers, D. (1999), “Functional testing using rapid prototyped components and optical measurement”, Optics and Lasers in Engineering, Vol. 31 No. 6, pp. 411-424. Yan, X. and Gu, P. (1997), “A review of rapid prototyping technology and systems”, Computer-Aided Design, Vol. 28 No. 4, pp. 307-318. Yang, H.J., Hwang, P.J. and Lee, S.H. (2002), “A study on shrinkage compensation of the SLS process by using the Taguchi method”, International Journal of Machine Tools and Manufacture, Vol. 42 No. 11, pp. 1203-1212. Yeong, W.Y., Chua, C.K., Leong, K.F. and Chandrasekaran, M. (2004), “Rapid prototyping in tissue engineering challenges and potential”, Trends in Biotechnology, Vol. 22 No. 12, pp. 643-652. Zenha, H., Azevedo, L., Rios, L., Pinto, A., Barroso, M.L., Cunha, C. and Costa, H. (2011), “The application of 3-D biomodeling technology in complex mandibular reconstruction-experience of 47 clinical cases”, European Journal of Plastic Surgery, Vol. 34 No. 44, pp. 257-265. Zhou, J.G., Herscovici, D. and Chen, C.C. (2000), “Parametric process optimization to improve the accuracy of rapid prototyped stereolithography parts”, International Journal of Machine Tools and Manufacture, Vol. 40 No. 3, pp. 363-379

About the authors Sushant Negi is doing his PhD in Designing under the supervision of Dr Suresh Dhiman and Dr Rajesh Kumar Sharma from National Institute of Technology (NIT), Hamirpur, Himachal Pradesh (HP), India. He holds a 266

Basics and applications of rapid prototyping medical models

Rapid Prototyping Journal

Sushant Negi, Suresh Dhiman and Rajesh Kumar Sharma

Volume 20 · Number 3 · 2014 · 256 –267

Bachelor degree in Mechanical Engineering from Punjab Technical University Jalandhar, India (2009) and a Master’s degree in CAD/CAM from NIT Hamirpur, India (2011). His areas of interests include rapid prototyping, design, and tribology.

experience in the field of manufacturing. He is presently working as an Assistant Professor in the Mechanical Engineering Department at NIT, Hamirpur (HP), India. He has publications in international/national journals and conferences to his credit in the area of optimization of machining parameters, development and characterization of metal-matrix composites and RP. Suresh Dhiman is the corresponding author and can be contacted at: sudhi_ [email protected]

Suresh Dhiman completed a four-year Post Diploma in Mechanical Engineering from the YMCA Institute of Engineering, Faridabad, Haryana (India), in 1986, graduation in Mechanical Engineering from the Institution of Engineers (I), Kolkata, in 1996, post graduation (MTech) in Production Engineering from the Guru Nanak Dev Engineering College, Ludhiana (Punjab), in 2001 and PhD in Mechanical Engineering from NIT, Kurukshetra, Haryana, India, in 2008. He possesses ten years of industrial

Rajesh Kumar Sharma is an Associate Professor in the Department of Mechanical Engineering at NIT, Hamirpur (HP), India. He completed his doctoral work from IIT Delhi in 2008. His areas of interest include noise control, design and tribology.

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