Single-Exposure, Dual-Energy Subtraction Flat Panel X-Ray Detectors: A Health Technology Assessment.

Abstract

Background: In medicine, x-rays are used to generate images of tissues and structures inside the body. X-rays are emitted by a source device and, after passing through the body, strike a detector, which forms an image of the tissues and structures the x-rays passed through. Dual-energy subtraction (DES) x-ray systems use radiation of different energy spectra (energy levels) and the principle of differential absorption characteristics of bone and soft tissue to produce separate bone and soft tissue x-ray images, in addition to a conventional x-ray image. The aim is to minimize potential issues with anatomical overlap with conventional x-ray that may obscure some findings. Single-exposure, DES flat panel x-ray detectors produce a conventional x-ray image in addition to DES bone and soft tissue x-ray images using a single x-ray exposure. We conducted a health technology assessment of single-exposure, DES digital flat panel x-ray detectors in adults for indications such as pneumonia, pneumothorax, and pulmonary nodules, and for visualizing lines and tubes, compared with conventional x-ray. Our assessment included an evaluation of the diagnostic accuracy, the impact on diagnostic confidence, patient management and clinical outcomes, the budget impact of publicly funding the technology, and the experiences, preferences, and values of health care providers.

Methods: We performed a systematic literature search of the clinical evidence. We assessed the risk of bias of each included study using the QUADAS-C tool and the quality of the body of evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria. We performed a systematic literature search on the economic evidence of single-exposure, DES flat panel x-ray detectors. We did not conduct a primary economic evaluation because of limited evidence on the implications of this technology. We analyzed the budget impact of publicly funding single-exposure, DES flat panel detectors in Ontario hospitals. To contextualize the potential value of single-exposure, DES flat panel x-ray detectors, we spoke with people with expertise in diagnostic imaging, including radiologists and other health care practitioners.

Results: The clinical evidence review identified 2 eligible observational studies that assessed the use of single-exposure, DES flat panel x-ray detectors to generate DES bone and soft tissue x-ray images and a conventional x-ray image. The findings of 1 study suggest an improvement in the sensitivity and specificity for the detection of pulmonary nodule calcification with the use of single-exposure, DES soft tissue and conventional x-ray images compared with using a conventional x-ray image alone (results were statistically significant for 2 out of 5 reviewers; GRADE: Low). In one study, x-ray image reviewers reported an improvement in the visibility of the tips of lines and tubes (although these were visualized with the conventional x-ray image alone) in all patients and an improvement in the diagnostic confidence in 16 (57.1%) patients, with no difference in the time to review the images with the use of single-exposure, DES bone and soft tissue x-ray images plus the conventional x-ray image compared with using the conventional x-ray image alone, but the evidence is very uncertain (GRADE: Very low).The economic evidence review identified 1 costing study in the US setting. This analysis suggested adoption of single-exposure, DES x-ray detectors may lead to cost savings. However, this study was deemed not directly applicable to the Ontario setting. The cost-effectiveness of single-exposure, DES flat panel x-ray detectors is therefore unknown. Owing to the limited evidence on the impact of these detectors on short-term outcomes such as diagnostic accuracy and workflow, and long-term costs and health outcomes, we did not conduct a primary economic evaluation. Our budget impact analysis estimated that, for a typical community hospital, purchasing 3 detectors to retrofit existing x-ray machines would lead to an additional cost of $12,137 per institution. However, there is a large degree of uncertainty around the downstream costs and benefits of this technology.We interviewed 20 health care providers who had expertise with x-ray systems. Those who had the opportunity to interpret the x-ray images produced by a single-exposure, DES detector in a clinical setting were supportive of this technology and perceived an increase in confidence with diagnosing patients. Retrofitting existing x-ray systems to be compatible with the single-exposure, DES detector posed a challenge for operators as it was not a seamless process. Those who operated the retrofitted x-ray systems using the single-exposure, DES detector commented on issues related to workflow, including the physical specifications, connectivity, battery life, and maneuverability as barriers to use. Participants who did not have experience using the DES detector technology expressed uncertainty regarding the benefits compared to the alternative options currently in use in Ontario, such as image enhancing software, emerging artificial intelligence technology, and low-dose CT scanning. None of the users had experience with a fully integrated mobile x-ray system (i.e., a mobile x-ray system that did not require retrofitting to be compatible with the single-exposure, DES detector).

Conclusions: The use of single-exposure, DES flat panel x-ray detectors may lead to an improvement in the sensitivity and specificity to detect pulmonary nodule calcification compared with conventional x-ray, but the evidence is very uncertain for its effect on the visibility of the tips of lines and tubes, diagnostic confidence, and time to review the x-ray images compared with conventional x-ray. Evidence gaps include lack of evidence for the use of the technology for most populations and outcomes that we sought to evaluate. Due to limited clinical and economic evidence, the cost-effectiveness of single-exposure, DES flat panel x-ray detectors is currently unknown. We estimate that purchasing 3 detectors to retrofit with existing x-ray machines may lead to an additional cost of $12,137 per institution. Users of single-exposure, DES x-ray detectors who viewed and interpreted the images produced spoke positively about their experience with the technology and expressed an increase in confidence when making a diagnosis. Participants who operated the retrofitted single-exposure, DES x-ray detector commented on issues that negatively impacted their workflow. The experiences of providers with a fully integrated system are unknown at this time.