New Uses in Medical Applications

ESWL Products Inc.’s (Elk Grove Village, IL) Lithowave lithotripter is a noninvasive device for treating kidney stones. The Lithowave consists of an electrohydraulic spark gap energy source, a fluoroscopic localization system and a multifunctional operating table. The unit performs extracorporeal shock wave lithotripsy, which is a nonsurgical procedure in which shock waves are produced by the machine outside the body and focused on kidney stones inside the body. The shock waves break up kidney stones into smaller pieces, allowing them to pass through the body’s urinary system. To generate a shock wave, the unit uses spark gap technology, which harnesses the energy released during an electrical discharge between two electrodes submerged in water. When the reflected shock wave is positioned on the kidney stone, the repeated impact of the shock waves on the stone, at various energy levels, causes its disintegration. The Lithowave’s design has some distinct features. These include the positioning of both the treatment unit and the targeting fluoroscope on two frames mounted on one shaft and revolving around the same axis. This center-based design offers significant advantages over traditional designs. The system console controls and monitors the system. It allows the operator to control the treatment table, the lithotripsy systems, radiology and imaging. It is usually located in a separate control room or behind an X-ray shielding partition. A touch screen interface and fluoroscopy control panel are part of the control console. Additional controls and indicators are located on the side of the lithotripter enclosure. These switches are divided into three clusters to control main power, treatment unit positioning and a water system. After the stone is localized, the operator adjusts the position of the treatment unit and establishes correct contact between the patient’s skin and the membrane of the treatment unit. This part of the procedure uses the controls located on the control panel on the side of the main enclosure. The rest of the treatment is conducted from the system console. The Lithowave uses aluminum structural framing in its design. By using Bosch Rexroth Corp.’s (Buchanan, MI) aluminum structural framing, the company has been able to build a machine that is structurally stable and aesthetically pleasing, while also decreasing assembly time. The aluminum extrusions were used for the unit’s control cart. Aluminum was also used in the main structure, because weight was also an issue. The control cart is mobile and must be moved behind lead glass when operating the lithotripter. Aluminum structural framing assists assemblers with a simple T-slot design, allowing them to simply insert a T-bolt into a T-slot and tighten. The high-strength, extruded aluminum profiles also have a natural color and anodized surface that resists scratches and corrosion. It never needs painting or maintenance. In addition to the framing’s physical characteristics and benefits, Bosch Rexroth’s FMSsoft AutoCAD-based software reduced engineering and design time by providing product visualization and generating a bill of materials. FMSsoft is a suite of software programs for layout, planning and designing structures made with aluminum structural framing. It simplifies common tasks, improves efficiency and reduces the time needed to design structures. It also provides automatic parts list generation, integrated calculation, a 3D system library and fast- functioning macros. A similar control console using welded steel would take about 2 days to build compared with aluminum structural framing. The aluminum framing can be assembled in only hours. Design flexibility and the option to customize the height and width of components also factored into the company’s decision to use aluminum framing. It costs less, is more versatile, and in the case of the Lithowave, it does an overall good job.