Quality control of CR imagers has grown easier in recent years, due to the increased sophistication of these hard-copy printing devices. The most routine quality-control taskwhether the imager in question is of the wet or dry varietyis daily monitoring of sensitometry, H and D curves, and densitometry, says Bruce Apgar, applications manager of hard-copy equipment for Agfa Inc in Greenville, SC. In order to maintain optimum performance, Agfa recommends calibrating with each new box of film, a chore the company has sought to simplify with the introduction of an automatic calibration feature (available on the company's line of dry imagers), Apgar reports.

"With automatic film calibration, a calibration strip is printed every time a new box of film is loaded," he explains. "The imager automatically reads that strip and resets itself to deliver optimum performance."

Agfa's newest dry printerthe 4500M, specifically designed for outputting full-field digital mammography images on filmnot only performs automatic film calibration, it also runs a self-administered film test to meet the requirements of the federal Mammography Quality Standards Act, Apgar tells.

"The 4500M's test film consists of a step-wedge, a resolution target, and a geometric test-pattern," he says. "The wedge can be printed out at the user's discretion. Once printed, the wedge output can be read for densities, plotted and maintained for quality control charting.

"We're in the process of introducing new software that will automatically read the step-wedges and display the results on the front panel of the printer. This will eliminate having to manually read the densities in order to plot them and record them."

Apart from calibration, the only other major QC task pertaining to imagers is preventive maintenance undertaken monthly, semiannually, or annually, depending on manufacturer recommendations for the particular product, Apgar indicates.

"For our dry imagers, we advise users to have the equipment inspected at least once a year by our trained service technicians," he says. "We check, adjust, and, if necessary, replace the rollers, the transport system, and other moving parts. We also check the calibration of the onboard densitometer.

"For our wet imagers, we recommend monthly preventive maintenance inspections. The main thing we do here is removal of processor racks so that rollers can be cleaned and the system purged of chemical residue build-up. Then, the old chemicals are replaced with new."

When imagers are arrayed in a network, QC procedures need to be extended to include the device-to-communications infrastructure and connections, says Apgar.

"Our printers are typically DICOM compliant, so once an IP address and an AE title are assigned to one, the possibility of images being routed to the wrong place is extremely remote," he says. "Also, our  printers use a web-based operating systemthat means that when they're installed on a network, users can log on and open up a browser page to easily designate or modify configuration settings."

It is also a good idea to check daily the health of the network itself, making sure that traffic between nodes is flowing smoothly and that no data bottlenecks are developing. This is a task best performed by the user's information services department, Apgar suggests.

Another good idea is to verify at least weekly the consistency of patient information by sampling the data being embedded onto CR images. Inconsistencies in patient information can expose an enterprise to significant medical-legal risks. Inconsistencies, says Apgar, are most likely to show up if data is manually entered by technologists rather than imported direct from either a radiology information system or a hospital information system. b

Rich Smith is a contributing writer for Decisions in Imaging Economics.