The Ethics of Exposure
Radiography has been revolutionized by rapid technological advances resulting in more effective, efficient digital image modalities, including both computed radiography (CR) and digital radiography (DR) systems that are increasingly leveraged in balancing quality, workflow, and cost demands (Herrman, 2008). As organizations increasingly adopt these systems, image capture and manipulation are key areas of interest with correct exposure playing a central role in patient protection and image quality. Digital imaging has proven invaluable for patient diagnosis and management but the risk of radiation-induced malignancy presents a significant health care challenge as medical exposure contributes to cancer incidence and mortality (Yu et al., 2008). The lack of visual feedback on exposure can lead to the inappropriate use of technique factors. This review explores the link between stabilization and optimization, arguing the need for utilization of exposure indexes (EIs) as opposed to technical image manipulations so as to improve appearance while eroding positional and technical factor standards.
In total, the primary concern is how to leverage standards to prevent unnecessary exposure to radiation. The topic of radiation exposure in digital modalities is based on the larger dynamic ranges with CR/DR when compared to traditional methods; while systems may automatically adjust exposure, reliance on this strategy fails to uphold fundamental standards that assist in weighing the existing trade-off between image quality and patient exposure (Herrman, 2008). High quality images are vital to diagnostics; still, associated exposure risks and radiation dosing is imperative. For instance, use of automatic exposure control (AEC) and calibration levels can prove harmful to pediatric patients and caution is mandated to maintain the basic principles radiography in achieving the dual objectives of high quality and low dose (Moore et al., 2012). CR/DR technologies allow for a wider range of patient exposure but this capacity demands attention. According to Moore et al., (2012), greater education and awareness is needed in identifying and mitigating the potential adverse effects of ionizing radiation with emphasis placed on the relationship between technique and patient dose, especially amongst vulnerable pediatric patient populations that are more susceptible to these threats.
“Digital image processing adjustment of the brightness, contrast, and grayscale makes exposure appear appropriate; therefore, visually judging the radiographic technique and patient exposure is inappropriate” (Moore et al., 2012, p. 94). It is easy for overexposed images to go unnoticed given the technologies’ ability to maximize image quality. “Dose creep” occurs because there is no visual indication of improper techniques and overexposure and the clear evidence of underexposure (SUNY, 2011). Additionally, equipment differs in image acquisition and image processing, meaning that each instrument requires system-specific strategies for image optimization and exposure control. As such, Moore et al. (2012) recommend the development of a standard approach in digital imagery generation defined by clear feedback related to exposure and individual image quality assessment instead of the simplistic and potential hazardous reliance on image density.
Similarly, Herrman (2008) highlights the fact that routine system adjustments may subsequently increase radiation dose delivery over time, stating that dose increase commonly results from operators attempting to decrease image noise through incremental dosing increases. From this perspective, system operators have a major responsibility in quality control and patient protection. CR/DR image acquisition processes reduce the need for repeat image capture but, as stated, elements of underexposure and overexposure must be properly appraised. Quality controls are essential in maintaining technical parameters, radiographic positioning, and proper collamination; in terms of exposure, traditional techniques cannot be unquestionably transferred to CR/DR formats and processes.
Pongnapang (2005) warns against reducing radiation dose in switching from screen-film to CR systems, stating that CR image quality requires 20% more radiation exposure to obtain the standard signal to noise ratio of traditional image-gathering tactics as CR uses medium speed film. If exposure reduction is unwarrantedly used, image rejection rates increase due to poor exposure techniques, leading to retakes that further complicate this issue. Logically, patient exposure will inadvertently increase in order to achieve image quality mandated for proper diagnosis. In some instances, patients have been subjected to three to five times overexposure without the problem being identified (SUNY, 2011). While increased radiation exposure definitively improves image quality, this unethical technique is in direct violation of the principles governing the profession (Pongnapang, 2005).
In conclusion, dose management and quality controls are crucial given the possibility of intentionally and unintentionally circumventing standards is a real concern. Overexposure can be hidden. CR/DR diagnostic value is high but overexposure is counterintuitive to desired outcomes. The technologist needs feedback related to radiographic technique appropriateness due to the lack of visual verification and guidance indicating exposure appropriateness; exposure indicators are efficacious tools for providing this feedback thereby allowing technologist data to assist in understanding and correcting the cause and effect impact of applied radiography (Moore et al., 2012).
