Kari O'rourke 0000-00-00 00:00:00
Total Quality Tool What makes the HPX-1 diagnostic tool unique among modern process monitoring tools is its automated nature. As digital radiography becomes more prominent in the nondestructive testing (NDT) industry, there is a growing concern among companies to monitor the performance and stability of their imaging systems. In some cases, system monitoring is required, but for other companies it is out of the need to protect their investment and be proactive. By using a diagnostic tool, companies may be able to spot a trend toward performance degradation before it becomes a real problem, or before it becomes apparent in their routine or production images. Even before one of the parameters goes out of spec, they would be alerted that it might be almost time for a recalibration or routine service. To keep up with this demand, Carestream Health (Rochester, NY) has designed the HPX-1 diagnostic system that employs a patented phantom and an automated tool to perform a variety of tests on the HPX-1 computed radiography (CR) reader, characterizing and monitoring key imaging performance parameters. Currently, there are a variety of phantoms being used for performance monitoring, but what makes the HPX-1 diagnostic tool unique is its automated nature. It eliminates subjective judgment and tedious analysis for the operator and provides speed, objectivity and accuracy. “As more operators adopt digital radiography (DR), they are naturally concerned with getting the optimal performance from their imaging systems. Many industry prime contractors that require critical inspections also require their contractors to certify and document the performance and stability of their imaging systems,” says Steve Mango, worldwide technical manager at Carestream Health. “Operators need to do this in the most accurate and efficient manner possible, with minimal impact on workflow. While such automated systems exist in the medical field, they have not been available to the NDT industry until now.” The system has an interface that allows the operator to scan an exposed imaging plate and obtain an immediate reading on the health of the system with status lights for each of the system tests. The calculations are then evaluated against a table of projected results and tolerances, and if the results are “good to go,” then a green light is triggered. An amber light is set off when results are approaching the limit, and a red light indicates when the system needs to be recalibrated or serviced. A ready indication lets the operator know that the test is ready to go but has not yet been completed. “The analysis is all automated, so the operator need not to be a scientist and does not need to understand the intricacies of modulation transfer function or detective quantum efficiency. Any operator who can manage a CR system can use this tool,” says Mango. When an image is scanned at a particular pixel pitch, the apertures are imaged at precise locations relative to each other. The software then analyzes the data to locate transitions in pixel values to precisely locate each of the apertures. Using the location of the apertures in the phantom, the tool calculates a variety of parameters relating to geometric accuracy, such as pixel size in both fast and slow scan directions, pixel aspect ratio, scan nonlinearities and pixel placement error. At the ASNT show last fall, the HPX-1 diagnostic tool was met with overwhelming response. According to Mango, show attendees indicated it would inspire confidence in their examination results, improve their workflow, and generally make their jobs easier and more cost efficient. The monitoring system was released this past February. It is ideal for critical applications such as aerospace, petrochemical, power generation, nuclear and wherever certification or documentation of imaging system performance is required or desired. Although the technology is designed specifically for the HPX-1 digital system released last year, the basic philosophy also can be applied to any CR or DR system. SPECIFICATIONS A simple phantom for monitoring digital imaging system performance is employed. The software can precisely locate the position of each aperture. The precise locations of the reference markers (apertures) are used to compute a variety of geometric parameters; in this example, pixel aspect ratios. The system stores all test results for the past year, which can be reviewed individually or collectively, in logs, tables or graphs.
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