What began with brittle parts made within hours for prototyping purposes, only, has evolved into a family of rapid digital technologies used to produce durable, long-lasting parts for finished products within hours and in some cases, minutes, and to capture, build and work with digital 3D geometry.

It's been more than 20 years since 3D Systems, Rock Hill, S.C., rocked the manufacturing world with the first-ever stereolithography rapid prototyping system by 3D Systems, Rock Hill, S.C. Today, rapid prototyping is part of a broader category known as rapid manufacturing. These technologies are being used as problem-solving tools for medical-device research and development as well as for their design and manufacturing of medical devices. Digitally fabricated objects are no longer made to serve only as prototypes. Increasingly, the objects are finished products, manufactured by skipping the intermediate steps of traditional fabrication and tooling. Device designers are now getting medical into the act.

CT scans (computerized tomography), MRIs (magnetic resonance imaging), and DICOM (digital imaging and communications in medicine) image sets can be turned into models of organs, bones, and tumors thanks to the efforts of several software developers. For instance, Mimics 3D image processing and editing software by Materialise, Leuven, Belgium, (materialise.com), 3D reconstruction software by Javelin 3D, Park City, Utah, javelin3d.com, and advanced image freeware by Osirix, (osirixfoundation.com) take stacks of radiology data and build layered models by automatically tracing the outlines of the images and reconstructing them into 3D models. Furthermore, these patient-data files can be used for medical models and direct digital metal fabrication of custom implants made of titanium and cobalt-chrome alloys.

Other examples of rapid digital technologies for medical applications:

• Mako Surgical, Ft. Lauderdale, Fla., (makosurgical.com) produces the Makoplasty robotic tactile feedback guidance system for precision resection of joint tissue for minimally invasive implant placement, based on the patient's radiology data.

• ConforMIS, Burlington, Mass., (conformis.com) produces custom-made joint implants and positioning guides based on the patient's radiology data.

• Sirona Dental, Long Island City, N.Y., (sirona.com) makes the Cerec system that digitally scans dental anatomy, and produces a ceramic replacement crown using CAD/CAM technology.

• Align Technology, Santa Clara, Calif., (aligntech.com) makes the Invisalign invisible orthodontic brace system, and utilizes rapid technologies in its production processes.

• SensAble, Woburn, Mass., (SensAble.com) makes the Dental Lab System, an integrated suite that lets a dentist to digitally scan dental anatomy to design and build crowns and bridges. The technician sculpts and designs the wax casting master in a digital environment with the Phantom input stylus, providing virtual reality force feedback.

• 3D Systems, Rock Hill, S.C., (3Dsystems.com) recently launched the V-Flash for direct digital manufacturing of custom hearing aid shells in an FDA-approved material.

• Biomet Corporation, Warsaw, Ind., (biomet.com) uses rapid technologies to make customized implants from datasets derived from CT scans. The company's Signature positioning guides for knee replacement surgery are single-use custom guides that are built from the patient's radiology data and produced with Fused Disposition Modeling by Stratsys, Eden Prairie, Minn., (stratasys.com) to help ensure accurate fit and function of the orthopedic implant.

• EOS GmbH, Munich, Germany, (eos.info/) and Arcam, Mölndal, Sweden (arcam.com) are direct manufacturing orthopedic implants suitable for human use from e-beam and laser energy-fused advanced engineering materials such as cobalt-chrome and titanium. EOS GmbH is marketing implants for human use in Europe.

• The Medical University of South Carolina, Charleston, is developing tissue-engineering methods using rapid technologies. There, under the direction of Dr. Vladimir Mironov, ink-jet printing technology is used to build constructs of hydrogels and living tissue with the goal of one day growing replacement tissues and organs.

• The Johns Hopkins Hospital, Baltimore, use rapid technologies to scan, capture, visualize, and model data. Rapid technologies are used to scan facial features and rebuild them with anaplastology.