Quality assurance of computed and digital radiography systems

Abstract

Computed radiography (CR) and digital radiography (DR) are replacing traditional film screen radiography as hospitals move towards digital imaging and picture archiving and communication systems (PACS). Both IPEM and KCARE have recently published quality assurance and acceptance testing guidelines for DR. In this paper, the performance of a range of CR and DR systems is compared. Six different manufacturers are included. Particular attention is paid to the performance of the systems under automatic exposure control (AEC). The patient is simulated using a range of thicknesses of tissue equivalent material. Image quality assessment was based on detector assessment protocols and includes pixel value measures as well as subjective assessment using Leeds Test Objects. The protocols for detector assessment cover a broad range of tests and in general detectors (whether DR or CR) performed satisfactorily. The chief limitation in performing these tests was that not all systems provided ready access to pixel values. Subjective tests include the use of the Leeds TO20. As part of this work, suggested reference values are provided to calculate the TO20 image quality factor. One consequence of moving from film screen to digital technologies is that the dynamic range of digital detectors is much wider, and increased exposures are no longer evident from changes in image quality. As such, AEC is a key parameter for CR and DR. Dose was measured using a standard phantom as a basic means of comparing systems. In order to assess the AEC performance, exit doses were also measured while varying phantom thickness. Signal-to-noise ratios (SNRs) were calculated on a number of systems where pixel values were available. SNR was affected by the selection of acquisition protocol. Comparisons between different technologies and collation of data will help refine acceptance thresholds and contribute to optimising dose and image quality.

The effects of image acquisition control of digital X-ray system on radiodensity quantification

“…This study was done to evaluate the effects of different IAC modes on ASW eRD quantification of restoration materials under different exposure conditions. Studies have shown that there are no significant differences in image quality of the various sensor systems currently available 15-18. For the current study, we have used a CMOS based digital radiography system.…”

Vergleich der Bildqualität zweier unterschiedlicher mobiler 3-dimensionaler Röntgen-C-Bögen mit einem konventionellen CT bei der Darstellung relevanter Strukturen am knöchernen Becken

“…Hierzu wurden subjektive wie auch objektive Bewertungskriterien verwendet. Unter anderem durch die vermehrte Anwendung digitaler Röntgengeräte wurde die Strahlendosis für den Patienten in der Vergangenheit bereits reduziert und die Bildqualität gleichzeitig verbessert [24,25]. Diese Tatsache zeigt auch, dass eine höhere Strahlendosis nicht immer eine bessere Bildqualität bedeuten muss.…”

Radiographers’ experiences of the management of quality assurance programmes in public hospitals, South Africa

“…Recommendations from the International Commission on Radiation Protection (ICRP) formed the basis for national and international standards of radiological protection and were accepted by the South African Department of Health Directorate Radiation Control (SADOH DRC) in 2001. 7 Although QA programmes were implemented in 2001 and declared essential, monitoring of the performance of QC tests only became compulsory in SA in 2009. 3 Accredited vendor companies are responsible for ensuring that the QC tests are performed at the prescribed intervals as per regulation of the Directorate Radiation Control (DRC).…”