Abstract
Digital radiographic imaging systems, such as those using photostimulable storage phosphor, amorphous selenium, amorphous silicon, CCD, and MOSFET technology, can produce adequate image quality over a much broader range of exposure levels than that of screen/film imaging systems. In screen/film imaging, the final image brightness and contrast are indicative of over- and underexposure. In digital imaging, brightness and contrast are often determined entirely by digital postprocessing of the acquired image data. Overexposure and underexposures are not readily recognizable. As a result, patient dose has a tendency to gradually increase over time after a department converts from screen/film-based imaging to digital radiographic imaging. The purpose of this report is to recommend a standard indicator which reflects the radiation exposure that is incident on a detector after every exposure event and that reflects the noise levels present in the image data. The intent is to facilitate the production of consistent, high quality digital radiographic images at acceptable patient doses. This should be based not on image optical density or brightness but on feedback regarding the detector exposure provided and actively monitored by the imaging system. A standard beam calibration condition is recommended that is based on RQA5 but uses filtration materials that are commonly available and simple to use. Recommendations on clinical implementation of the indices to control image quality and patient dose are derived from historical tolerance limits and presented as guidelines.
Highlights
The charge of TG116, as approved by the Science Council of AAPM, was to identify a method of providing feedback, in the form of a standard index, to operators of digital radiographicDRsystems, which reflects the adequacy of the exposure that has reached the detector after every exposure event
Unlike screen-film imaging, image display in digital radiography is independent of image acquisition
In attempts to purchase alloy 1190, the authors were unsuccessful in finding an off-theshelf source; alternatively alloy 1100 is a 99.0% pure Al alloy that is widely available on the market
Summary
The charge of TG116, as approved by the Science Council of AAPM, was to identify a method of providing feedback, in the form of a standard index, to operators of digital radiographicDRsystems, which reflects the adequacy of the exposure that has reached the detector after every exposure event. Inadequate or excessive exposure is manifested as higher or lower image noise levels instead of as light or dark image. Overexposed images may not necessarily be dark, and underexposed images may not appear light. This may be a new and confusing concept for operators of digital radiographic systems who are accustomed to screen-film imaging. Task Group 116 has recommended 0.5 mm copperCuwith 0–4 mm of alloy 1100 aluminumAlas an alternative x-ray beam hardener to obtain the same RQA5 spectrum as specified in IEC 61267:2005.12 IEC 61267 requires the use 99.9% pure aluminum for the RQA5 radiation qualities. In attempts to purchase alloy 1190, the authors were unsuccessful in finding an off-theshelf source; alternatively alloy 1100 is a 99.0% pure Al alloy that is widely available on the market. Registered with 99.9% purity, which is higher than what is considered the highest purity commercial grade Al with 99.45%.32 Alloy 1190 falls into the category of scientific gradealso called ultrapure aluminumand is available only through specialty metals companies for a high price and in small quantities and limited form.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
