MARKET PLACE
 |
The challenge
Medical devices are produced in large numbers and it is critically important that they always work. A device with an internal component slightly offline in manufacture may pass a functional or visual test, but could jam later at a hazardous time. Picking one faulty product out of a line of thousands can be hard if, for example, the components are all made from similar plastic compounds or if delicate internal components are just slightly out of line. To make the quality control task more demanding, the position of each internal component needs to be accurately measured in all three dimensions on a conveyor belt moving past at speed. Recent three-dimensional (3D) X-ray technology can do this to an accuracy of approximately the width of a human hair, say its developers. The technology is suitable for medical devices where measuring the position of a component is important, even when products are constructed from dense materials or metals such as aluminium foil, which eliminates the use of alternative technologies such as optical, microwave and radio frequency.
The technique
Conventional X-ray imaging produces only a two-dimensional “shadow-like” image that can be difficult to interpret. Objects appear to be superimposed one over another, with no indication of their relative depth and none of the visual cues people normally use to understand the real world. Recent developments in X-ray technology offer 3D images; reportedly low-cost, precise X-ray sources; line-scan X-ray detectors; and image processing analysis, control, communication and decision-based software that was developed for use in the security industry to identify bombs, organic material and other terrorist threats.
 |
Figure 1: Dual arrays scanner line-scan detectors. |
A 3D image is achieved by simultaneously acquiring two views of the product being inspected from slightly different angles as it moves past on a conveyor. The resulting images are analysed and comparison of the two views allows the components to be measured. A series of views are taken “slice-by-slice” as the conveyor moves through the line-scan detectors (Figure 1). A PC processes the information to produce a single 3D data set that describes the object and its contents in real time. Because the system (comprising the source, the product being X-rayed and the two sets of detector) has a fixed geometry, it is a relatively simple exercise to calibrate the data; to provide accurate, repeatable 3D information; and to feed this into a quality control system.
The software provides automatic selection of image processing functions and optimises any desired aspects of an X-ray image. This capability fits naturally with the high resolutions now available from the latest X-ray sources. New features include the ability to resolve the boundaries between close-fitting components, even when they are manufactured from similar or different components. Thus, if a part or component is misshaped, misaligned or merely missing, 3D X-ray technology gives manufacturers the opportunity to detect it, even under difficult circumstances. This technology can help relieve concerns of product recall and liability.
 |
Figure 2: Lancets in a row.
|
Applications
Potential medical device applications include the alignment of components inside, for example, an asthma inhaler or any other medical device where the components are “hidden” such as inside other components or a container. The technology is also suitable for checking needle straightness in lancets (Figure 2) and syringes, where, because of their small size and concealed positions, checking needle straightness is an important concern.
For more information contact Nick Fox, Managing Director, 3DX-Ray Ltd, Pera Innovation Park, Nottingham Road, Melton Mowbray LE13 0PB, UK, tel. +44 1664 503 600, e-mail: info@3dx-ray.co.uk, www.3dx-ray.co.uk.
