Quality Acceptance Testing within Digital Projection Imaging

Published on 12/06/2015 by admin

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Last modified 12/06/2015

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Quality Acceptance Testing within Digital Projection Imaging

Objectives

On completion of this chapter, you should be able to:

• Discuss total quality management and its uses in digital projection imaging.

• Describe the daily, weekly, and monthly quality control (QC) activities assigned to a radiologic technologist.

• Explain the importance of establishing a repeat analysis database with digital projection imaging.

• State the common QC activities performed by a service engineer on digital projection imaging equipment.

• Become familiar with problem reporting responsibilities.

• Recognize the quality management (QM) and QC activities to be performed by the radiation physicist.

• Acknowledge personal responsibilities for correctly marking images, maintaining personal repeat rates, and artifact prevention.

Key Terms

Total quality management (TQM)

Preventative maintenance (PM)

Total Quality Management

Maintenance of equipment, image acquisition, and processing standards are quality control issues that fit into the concept of total quality management (TQM) or continuous quality improvement (CQI), as discussed in Chapter 11. The overall efficiency and effectiveness of imaging systems are evaluated beyond the mechanics of producing radiographic images. This chapter introduces the concept of whole system evaluation, considering image acquisition, processing, and evaluation issues as well as examination repeat analysis, communication issues, and system problem identification.

Quality Control Standards

The American College of Radiology requires compliance with standards of practice to assure quality in any imaging system. Three general areas define digital image quality: contrast, resolution, and noise. These areas must be monitored to avoid unnecessary repeat examinations and overexposure to patients and staff. There are a number of system tests that must be performed by service personnel and/or radiologic technologists and radiation physicists. With the increased sophistication of digital radiographic equipment, it is critical that these tests be performed in a consistent and thorough manner.

The American Association of Physicists in Medicine publishes the following documents based on work accomplished by task groups:

• Task Group 116—An Exposure Indicator for Digital Radiography

• Task Group 150—Acceptance Testing and Quality Control of Digital Imaging Units

• Task Group 10—Acceptance Testing and Quality Control of Photostimulable Storage Phosphor Imaging Systems

The following sections are in no way an exhaustive list of activities that should be performed. The manufacturer’s suggested list of systems tests should be performed as indicated in the equipment and service manuals.

Quality Control Schedules and Responsibilities

The radiologic technologist is the first line of defense in preventing, recognizing, and reporting quality control (QC) issues. Quality control is defined as a comprehensive set of activities designed to monitor and maintain a system or piece of equipment. The complicated and delicate nature of digital equipment necessitates frequent and consistent oversight to avoid image errors and unnecessary patient exposure. The following is a suggested schedule for proper digital system maintenance.

Technologist Responsibilities

Daily (Box 12-1)

• General system inspection including the following:

• Sensitometry

• Laser-generated sensitometry strip; film densities measurement

• Inspect images

• Dust particles, scratches, mechanical friction marks

• Network queue check

• Send images to picture archiving and communication system (PACS)

• Cleanliness of cassettes

• Are the cassettes free of dirt and debris on all surfaces? Dirt on the outside or inside of the cassette can result in an artifact in the image. The artifact could be an exposure artifact or processing artifact depending on when it occurs.

• Are barcode labels in good condition and able to be read? Labels in disrepair will compromise the connection of the imaging plate identification to the patient and exam identification information.

• Hinge and latch inspection

• Are hinges and/or latches in good condition? Broken latches or hinges can damage readers and will require a service call to get the reader in working order.

• Erasure of imaging plates

• Have plates been left unexposed for longer than 24 hours? The imaging plates that have not been erased recently have the potential to record exposure such as prolonged light exposure or scatter radiation. The safest procedure is to erase cassettes before use if unsure of the last erasure performed.

• Verification of digital interfaces and network transmission

• Is the reader communicating with the workstation? Are barcode readers working properly? Again, it is critical to maintain the link between the imaging plate and patient information.

• Inspect the laser printer for ink and paper. Make sure the printer is clean and the output bin is free of obstructions. If the printer can be used manually for copies, inspect the printer glass for dirt, fingerprints, etc., and clean according to the manufacturer’s specifications. Artifacts produced by dirt and fingerprints can appear and be interpreted as pathology, possibly resulting in false positive diagnoses.

Box 12-1

Summary of Radiologic Technologist Daily QC Duties

Inspect and clean cassettes

Inspect hinge and latch

Erase imaging plates

Verify digital interfaces and network transmission

Inspect laser printer

Weekly (Box 12-2)

• Clean and inspect receptors

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