Continuous Quality Improvement for Digital Radiography
Continuous quality improvement is a process to ensure that every employee plays a role in ensuring a quality product, and it includes two major elements, quality assurance (QA) and quality control (QC). While QA primarily deals with the administrative aspects of patient care and quality outcomes, QC addresses the more technical aspects of equipment performance. Both QA and QC play major roles in dose optimization that is a radiation protection principle to keep the dose as low as reasonably achievable (ALARA) without affecting the diagnostic quality of the image. QC is a common activity of technologists, medical physicists, and radiologists working in a medical imaging department, and it involves at least three essential tasks: that of acceptance testing, routine performance, and error correction. Furthermore acceptance criteria or tolerance limits for the recommended digital radiography QC tests, in which both qualitative and quantitative criteria may be used to assess image quality are provided.
A quality image is one that makes accurate diagnosis possible. This is known as “diagnostic quality.” The quality of any image can be described in terms of spatial resolution, contrast resolution, noise, detective quantum efficiency (DQE), and artifacts. QA and QC activities demand an understanding of the processes and errors in digital radiography. A process map which is a flowchart of the steps involved in performing a DR exam can be created as a way to understand the interrelationships between activities within the imaging operation. There are at least 16 steps that begin with the arrival of the patient in the imaging department to the step (step 16) where the images are released to the picture archiving and communication system (PACS). The process map draws attention to errors in the association of demographic and exam information, errors that can be avoided by periodic testing, errors in performing the examination, and errors in the delivery of the images. Additionally, reject analysis is an essential element of QC activities, and it is a time-honored method for assessing and improving quality of imaging operations.
Examples of several QC tests that employ qualitative criteria for acceptance limits have been described briefly and include tests for dark noise, computed radiography imaging plate test for uniformity and spatial accuracy, and erasure thoroughness. Furthermore, ongoing QC is an essential element and process of any digital imaging department, and as such the American Association of Physicists in Medicine (AAPM) has provided guidance details of such activities such as reject image analysis, exposure analysis, and artifact identification. The AAPM, the American College of Radiology (ACR), and the Society for Imaging Informatics in Medicine (SIIM) identify and describe at least five individuals who should play a significant role in QA/QA programs including the physician, a qualified medical physicist (QMP), registered radiologist assistant, radiologic technologist, and the imaging informatics professional.
Digital mammography is now an acceptable modality in most imaging departments, and the ACR provides recommendations for full-field digital mammography quality control in which they provide a list of 13 QC tests specifically for the technologist and 17 QC tests to be carried out specifically by the qualified medical physicist.
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