Best Practices in Digital Radiography

WHITE PAPER Best Practices in Digital Radiography Daniel N. DeMaio, MEd, R.T.(R)(CT); Tracy Herrmann, PhD, R.T.(R); Lauren B. Noble, EdD, R.T.(R); Denise Orth, MS, R.T.(R)(M); Paulette Peterson, MEd, R.T.(R)(M)(QM); Jason Young, BS, R.T.(R); Teresa G. Odle, BA, ELS Published by the American Society of Radiologic Technologists, 15000 Central Ave. SE, Albuquerque, NM 87123-3909. ©2019 American Society of Radiologic Technologists. All rights reserved. ASRT prohibits reprinting all or part of this document without advance written permission granted by this organization. Send reprint requests to ASRT. WHITE PAPER Best Practices in Digital Radiography Daniel N. DeMaio, MEd, R.T.(R)(CT); Tracy Herrmann, PhD, R.T.(R); Lauren B. Noble, EdD, R.T. (R); Denise Orth, MS, R.T.(R)(M); Paulette Peterson, MEd, R.T.(R)(M)(QM); Jason Young, BS, R.T. (R); Teresa G. Odle, BA, ELS eports on medical imaging use and resulting Digital imaging methods now are common across radiation exposure have increased following a all indications for and forms of radiography, including series of widely publicized incidents of exces- fluoroscopy and mammography. As radiographers have sive patient exposure to low levels of radiation adjusted to the widespread use of digital radiography, Rduring medical imaging examinations or procedures. they have had to refine exposure technique selection Increases in exposure initially were attributed to rising and pay closer attention to radiation protection. Digital utilization of medical imaging as technology has technologies offer many benefits for acquiring and post- improved the ability to diagnose and evaluate a wide processing images. As a result, radiographers must be variety of diseases and conditions. However, the particularly concerned about exposure technique and increased attention also likely can be attributed to the possibility of using more radiation than necessary. growing concern over risks attributed to medical radia- Radiographers assume extensive responsibility in tion exposure. Concerns and actions of regulatory bod- the radiation safety of patients. The American College ies, clinical societies, and the public continue to intensi- of Radiology (ACR) White Paper on Radiation Dose in fy despite a lack of evidence that exposure to low doses Medicine places the final responsibility for additional of ionizing radiation increases cancer risk. Further action before radiation exposure on radiographers. advances in technology and reimbursement changes Further, the paper states that “technologists are respon- have led to increased use of digital radiography and sible for limiting radiation exposure to patients by standardized techniques for indicating exposure. ensuring that proper procedures and techniques are fol- The benefits of radiography have remained clear lowed.” A 2010 update to ACR panel recommendations over the more than 100 years of diagnostic medical on radiation dose in medicine confirmed the ACR’s imaging’s history. Another fact that has remained clear responsibility for taking specific actions but empha- is the critical role radiographers play in ensuring patient sized that several of its recommendations “encourage radiation safety during medical imaging procedures. radiology practices and departments to take a more pro- Radiographers must adhere to the “as low as reasonably active approach to radiation safety.” achievable” (ALARA) principle by keeping occupation- Radiation safety practices in support of dose opti- al radiation dose as low as possible. Radiographers also mization, as well as occupational radiation safety adhere to similar principles of keeping patient exposure practices, are based on justifying clinical appropri- as low as possible without affecting image quality when ateness of examinations and optimizing dose while performing digital radiography (dose optimization). maintaining image quality. The various exposure Best Practices in Digital Radiography 1 WHITE PAPER techniques that radiographers can use continue to all-inclusive document, nor should any of these recom- evolve. Radiographers must be familiar with the most mendations be taken as superseding institutional policy current dose-reduction techniques and must operate or state regulations. Much like the constantly advancing equipment optimally in accordance with safety and technology used during digital radiography, this white image quality policies and procedures. Because digital paper is meant to be a fluid, living document. radiography still is a relatively recent advancement, radiographers’ skill levels vary depending on initial edu- Digital Radiography Background cation and experience. Radiographers and their patients The first form of digital imaging, digital subtraction can benefit from a single source that offers background angiography, was introduced in 1977 and put to clinical information, best practices, and recommendations for use in 1980. Computed radiography (CR) technol- radiographers on optimizing digital radiography and ogy also was used in clinical practice beginning in the patient radiation safety. 1980s. CR uses a storage phosphor plate. According to IMV Medical, a medical imaging market research firm, Scope of White Paper although nearly 50% of radiography systems installed The ASRT has long championed radiation protec- in the United States in 2015 included CR equipment, tion in digital imaging for all age groups, as evidenced as many as 70% of sites with fixed CR systems said by the organization’s support of and participation in they were planning to purchase new DR equipment or the Image Gently and Image Wisely campaigns. ASRT retrofit CR equipment with DR in the coming year. In helped found and actively participates in these and 2017, the Centers for Medicare and Medicaid Services similar initiatives that aim to reduce radiation exposure (CMS) reduced payments by 7% to imaging providers from medical imaging and improve education about with claims for CR and analog (film-screen) examina- the issue to consumers and health professionals. In sup- tions in a concerted effort to encourage more radiology port of this area of professionalism, the ASRT publishes providers to switch to digital technologies and therefore educational and promotional materials for the public promote dose reduction. and the medical imaging community. In 2012, the Fewer imaging facilities use CR technology today ASRT released its first white paper on best practices in with DR (direct or indirect capture or conversion) as digital radiography as a significant and dedicated effort the modality of choice. Both the direct and indirect to promote radiation protection for patients and profes- types of DR technology measure attenuated rays and sionalism for radiologic technologists. produce electronic signals that are sent to software The 2012 white paper combined information from to rapidly produce images in grayscale format on a trusted sources such as ACR guidelines, textbooks, pro- monitor. The first flat-panel detector still is common fessional and government organizations, and periodical in modern systems. These indirect DR detectors used literature on exposure to support transition of radiogra- amorphous silicon as a photodiode, measuring the light phers to digital radiography. The paper also examined emitted from a scintillator material excited by exposure elements of best practices for digital image quality and to x-rays. Some fixed DR systems (dedicated chest radi- dose reduction techniques in digital radiography (DR) ography rooms, mammography systems, etc.) included from a radiographer perspective. charge-coupled devices (CCDs) to generate an elec- In 2018, the ASRT convened a new workgroup to tronic signal from the emitted light. Direct DR systems update and revise the 2012 best practice recommenda- commonly use amorphous selenium as a photoconduc- tions. This white paper is the result of a year-long effort tive material, directly converting the energy of x-ray to ensure timely and helpful guidance for practicing photons into electrical signal without the need for light radiographers. The best practices and recommenda- as an intermediary. Roch et al reported in 2016 that tions included in this white paper serve as a resource flat-panel detectors have been shown to lower radia- for radiographers who perform digital radiography tion dose to patients as much as 30% over CR phosphor examinations. This white paper is not, however, an technology. Indirect capture DR systems use either a 2 Best Practices in Digital Radiography WHITE PAPER CCD or indirect flat-panel detectors to capture x-rays image must have sufficient contrast to demonstrate dif- and process image data, although indirect flat-panel ferentiated structures and to be diagnostically useful. detectors offer superior quality to CCD detectors and Very high contrast (very few shades of gray) reduces are more common. the image to a scale of mostly black-and-white, which can also hinder visibility of anatomic details. In digital Dose Optimization and Image Quality imaging, display contrast is the ratio of brightness of When following the dose optimization principles, adjacent structures to one another, and the displayed radiographers should strive to minimize patient expo- grayscale represents the dynamic range of brightness sure during all radiography examinations. Including levels. mammography, radiography examinations represent Subject contrast is determined by different absorp- 74% of all radiologic examinations performed on both tion of the x-ray beam by various tissues,

Load more