key: cord-0915025-9n999mgj authors: Gange, Christopher P.; Pahade, Jay K.; Cortopassi, Isabel; Bader, Anna S.; Bokhari, Jamal; Hoerner, Matthew; Thomas, Kelly M.; Rubinowitz, Ami N. title: Social Distancing with Portable Chest Radiographs During the COVID-19 Pandemic: Assessment of Radiograph Technique and Image Quality Obtained at 6 Feet and Through Glass date: 2020-11-12 journal: Radiol Cardiothorac Imaging DOI: 10.1148/ryct.2020200420 sha: 56b894f178c7e86101bccb9bd0efa80eddbf1e01 doc_id: 915025 cord_uid: 9n999mgj PURPOSE: To develop a technique that allows portable chest radiography to be performed through the glass door of a patient’s room in the emergency department. MATERIALS AND METHODS: A retrospective review of 100 radiographs (50 [mean age 59.4 ± 17.3, range 22-87; 30 women] performed with the modified technique in April 2020, randomized with 50 [mean age 59 ± 21.6, range 19-100; 31 men] using the standard technique was completed by three thoracic radiologists to assess image quality. Radiation exposure estimates to patient and staff were calculated. A survey was created and sent to 32 x-ray technologists to assess their perceptions of the modified technique. Unpaired Ttests were used for numerical data. A P value < .05 was considered statistically significant. RESULTS: The entrance dose for a 50th percentile patient was the same between techniques, measuring 169 µGy. The measured technologist exposure from the modified technique assuming a 50th percentile patient and standing 6 feet to the side of the glass was 0.055 µGy, which was lower than standard technique technologist exposure of 0.088 µGy. Of the 100 portable chest radiographs evaluated by three reviewers, two reviewers rated all images as having diagnostic quality, while the other reviewer believed two of the standard images and one of the modified technique images were non-diagnostic. A total of 81% (26 of 32) of eligible technologists completed the survey. Results showed acceptance of the modified technique with the majority feeling safer and confirming conservation of PPE. Most technologists did not feel the modified technique was more difficult to perform. CONCLUSIONS: The studies acquired with the new technique remained diagnostic, patient radiation doses remained similar, and technologist dose exposure were decreased with modified positioning. Perceptions of the new modified technique by frontline staff were overwhelmingly positive. I n p r e s s 1. Portable chest radiographs can be performed with a six foot distance through a glass door with images that remain diagnostic compared to conventional portable radiographs. The described modified portable technique results in similar radiation dose to the patient and similar or decreased radiation to performing X-ray technologist. Increased distancing and placement of technologist and X-ray unit outside of the patient's room allowed for conservation of personal protective equipment with technologist's feeling safer. A modified portable chest radiography technique with increased distancing between the x-ray unit and detector provided diagnostic quality images with a similar radiation dose to the patient and staff while conserving personal protective equipment. The spread of the coronavirus disease 2019 (COVID-19) has placed an unprecedented strain on healthcare resources. Radiology departments around the world have been pressed to work in new and different ways to ensure that the level of services provided to patients is maintained while also ensuring staff safety. Chest radiography (CXR) has long been the front line test to assess for the presence of pneumonia and verify line and tube placement (1, 2) . Due to the current COVID-19 pandemic, portable chest radiographs are being maximized to reduce patient transfer, including in the emergency department (3, 4) . Extra precautions are justified as early stages of the infection are asymptomatic (5) . Most national guidelines do not recommend the use of CXR as a screening tool for COVID-19 however it can play in a critical role in assessing for pneumonia complications and excluding other pathology that can present with similar symptoms (6) . The standard procedure to acquire a portable CXR involves close contact between the technologist and the patient. Infection control guidelines require the technologist to use full personal protective equipment (PPE) consisting of a gown, gloves, face shield or goggles, and an N95 respirator (or equivalent airborne precaution protection) when imaging a COVID-19 positive or suspect patient. Disinfectant wipes are also needed to clean the x-ray machine. At our institution and across the globe, healthcare workers have been faced with shortages of PPE. Therefore, our health system leadership I n p r e s s asked all teams to develop methods to minimize PPE and disinfectant use while maintaining high quality care. In order to meet this goal, our radiology team worked together to modify the usual procedure for portable chest radiography. We hypothesized that a modified portable chest radiograph technique could be created with X-ray acquisition through the glass door of the patient's room that would allow for increased distancing between staff and patient, maintenance of diagnostic image quality, less PPE use, and similar patient and staff radiation exposure. This Health Insurance Portability and Accountability Act compliant retrospective study was performed following approval from our university institutional review board with waiver of informed consent. A team involving a senior technologist (KT), a medical physicist (MH), and three radiologists (JP, JB, IC) was formed to develop a new protocol for portable chest X-ray acquisition in the emergency department (ED) based on reports of increased distancing published by others (3, 4 A new technique was designed to acquire portable CXRs at 72 inches (6 feet) through a glass door which allows the technologist and the X-ray unit to remain outside of the room during image acquisition ( Figure 1 ). The increased distance requires a technique that emits a higher quantity and energy of radiation to ensure good penetration through the glass, adequate exposure at the detector, and low exposure duration to minimize motion blur. The six foot source-detector distance remains within the American College of Radiology practice parameters for portable chest radiography (7) . The detector is covered by two plastic bags and given to the nursing staff already in full PPE to place behind the patient's chest under direction of the X-ray technologist. Communication between the patient's nurse and technologist is needed so the X-ray acquisition is coupled with routine in room care. Once the image is acquired, the nurse partially removes the outside bag and the technologist grabs the inner bag containing the detector from outside the room while wearing a standard face mask. The new technique was instituted on each of the portable X-ray units used to obtain portable CXRs in the ED. Generic sizes were used by technologists in choosing technique, with parameters shown in Table 1 , although the technologists were free to adjust these parameters to the patient. A conventional anti-scatter grid was not used with the modified technique. Instead, the increased scatter radiation from high energy X-rays was adjusted for by using a scatter improvement software called SmartGrid (Carestream Health, Inc., Rochester, New York). SmartGrid is a commercially available post processing technique that provides image quality comparable to images acquired with an antiscatter grid (8) . Conventional anti-scatter grids are very sensitive to positioning errors resulting in grid cutoff. Since the detector was not going to be placed directly by the technologist, a software approach was chosen to minimize errors and yield an image with comparable contrast to noise ratio expected with a conventional anti-scatter grid. Exposure index (EI) values allow for estimates of radiation exposure at the detector (not patient dose) and can be used as a surrogate marker of image quality and signal to noise (9) . Importantly, the EI values can help the technologist know whether proper technique was used for the individual patient size to ensure that ALARA (as low as reasonably achievable) principles are followed (10, 11). The target EI chosen was 300, compared with 200 which is used for standard portable CXR, since using a higher kVP with the same target entrance exposure will result in a higher detector exposure because of less attenuation in tissue. Patient entrance skin doses were estimated using a look-up table from physical measurements and applying the inverse square law to a reference point 30 cm from the detector. Analysis was conducted with an anthropomorphic phantom to assess scatter radiation dose to staff using parameters and distancing of a typical portable X-ray and from the modified algorithm portable chest X-ray (12) . The first five radiographs obtained with the technique were assessed for diagnostic quality immediately after acquisition by the interpreting ED radiologist to ensure the images were adequate. These I n p r e s s radiologists had prior comparison exams available to review. Once the technique was refined, an SBAR (Situation-Background-Assessment-Recommendation) document was created ( Figure 2 ) to frame the communication to all staff, with inclusion of basic workflow for both the X-ray technologist and the patient's nurse. An estimation of PPE savings with the modified protocol was completed. A blinded retrospective review of radiographs taken both before and after the new technique was implemented was performed by three board certified, fellowship trained chest radiologists (IC, AB, CG) with 10, 4, and 2 years of experience to assess diagnostic image quality. The 50 portable CXR images taken with the modified technique were randomized with a control group of 50 portable CXR images taken with the standard technique. Examples of these images are included in Figure 3 . The 100 CXR images were randomized for radiologist review after anonymization and removal of all image notations. The radiologists were blinded to patient and image technique information, including history and indication for the exam. Each radiologist rated the images as diagnostic or non-diagnostic and noted if any parenchymal abnormality was present. The official reports of the 50 CXRs performed with the modified technique were also reviewed by a different chest radiologist (AR) for any mention of limitation described by the radiologist who interpreted the exam clinically. A web-based survey was sent to all 32 technologists who had performed portable CXRs in the emergency department at our primary hospital site from the time the modified technique was instituted. They were informed that their answers were anonymous. The survey consisted of six questions with a choice of responses assessing agreement using a 5-point Likert scale from strongly agree to strongly disagree as shown in figure 4 . The technologists were also able to add additional comments by free text. A I n p r e s s Statistical analysis was completed in Microsoft Excel (Microsoft, Redmond, WA). Unpaired T-tests were used for numerical data. A P value < .05 was considered statistically significant. Compared to standard technique, the modified protocol resulted in a higher exposure index to the detector (P < .001) across all patients ( Table 2 ). Measurements compiled after 1 week of using the modified technique demonstrated that the EI for a patient in 50 th percentile by BMI ("average sized patient") was 316, which was close to the target of 300 ( Table 2 ). The technologists did not use the lower kVp for smaller patients, as even patients in the 10 th percentile of BMI (21 kg/m²) were imaged using a kVp of 110. The mean BMI for the modified protocol patients was 30.2 ± 5.9 kg/m², and the mean BMI for the control group was 28 ± 6.5 kg/m² which was not significantly different (P = .08). The patient BMI values for the 10 th , 50 th , and 90 th percentile were 21, 29.4, and 41.4 kg/m² for the modified technique group and 19.9, 28.3, and 39.7 kg/m² for the control group. Entrance skin exposures were slightly increased but not significantly different for patients with a BMI less than the 50 th percentile (P = .06), but higher for patients with a BMI above the 50 th percentile (P = .004, Table 2 ). The estimated technologist entrance dose exposure when standing off to the side six feet from where the x-rays are intercepted by the glass (positioning shown in Figure 1B ) was less than the typical portable technique (7 µGy vs. 10 µGy). However, estimated dose when technologist was positioned six feet directly behind the X-ray unit was greater than a standard portable (16 µGy vs. 10 µGy). Of the 100 portable CXRs reviewed, two of the three radiologists considered them all to be diagnostic quality. The third radiologist felt that three of the 100 CXRs were nondiagnostic, two of which were performed with the standard technique and one of which was performed with the modified technique. Survey results from the X-ray technologists on the modified technique are detailed in Our study confirms that a modified portable chest radiograph technique with the technologist and X-ray unit remaining outside the patient's room results in no difference in diagnostic image quality compared to standard portable technique. Forty-nine of the 50 (98%) CXRs using the new modified technique were considered diagnostic quality by all three chest radiologists. In addition, interpreting radiologists who had prior images available for comparison did not report any limitations in their clinical reports. Actual emergency department cases during the pandemic were used, with almost half of the overall group having lung parenchymal abnormalities. This confirms the clinical value of the technique in a real world setting during the COVID-19 pandemic. Comparing parenchymal abnormalities to COVID lab test data was not possible with our sample because none of the control group had positive tests. The lack of positive testing is likely related to testing availability at that time since parenchymal abnormalities were present in many patients. Presence of abnormalities on chest radiograph is not being used to primarily diagnose COVID-19 and the chest radiograph is not part of the routine screening of these patients, as findings (if present) are non-specific and the CXR can also be normal in patients with a positive lab test (13, 14) . Our department and hospital have echoed the American College of Radiology recommendations that CXR and CT should not be used to diagnose COVID-19, but the tests are available, and clinicians often order them, for a variety of indications (6). Using entrance dose as a measure of patient radiation exposure, the dose was similar between techniques for patients in the 50 th percentile of BMI ("average size patients"), but slightly increased for patients with lower or higher BMI. Given the higher energy X-ray beam used in the modified technique, organ doses would be expected to be higher, however they were not calculated for this study. The EI was increased in all patients using the new technique reflecting a higher X-ray beam energy, but this was purposeful to allow for better penetration through the glass and increased distance the beam needed to travel. Future efforts can be focused on decreasing the EI for the new technique closer to the standard, however the amount of noise and motion blur in the images will be a limiting factor and will require continuing feedback from radiologists (15 quality portable X-ray systems, and a team based approach between ED nursing and radiology technologists, which may not be available at all institutions. We did not specifically study ED nursing opinion in this report and did not study this technique in the intensive care unit or on the clinical floors. Other departments looking to adopt this technique will need to verify that local factors, including the equipment and room construction, do not increase radiation dose or degrade image quality. Anti-scatter software was used in this study which may affect image quality. Lastly, the modified technique requires patient upright positioning (at least 45 degrees) which could limit the use for critically ill patients, I n p r e s s however the nursing staff is often able to tilt the beds forward to allow semi-upright position, allowing the majority of patients to be imaged with this technique. In summary, we describe a procedure of a modified portable chest radiograph technique using 72-inch unit to detector distance with images acquired through a glass door with the technologist and X-ray unit outside of the patient's room. Image quality remains diagnostic with no increase in technologist radiation exposure and similar patient radiation dose, while allowing conservation of PPE during the COVID-19 pandemic. This modified technique has been embraced as a positive initiative by frontline staff. I n p r e s s Imaging of Pulmonary Viral Pneumonia An assessment of the contribution of chest radiography in outpatients with acute chest complaints: a prospective study Policies and Guidelines for COVID-19 Preparedness: Experiences from the University of Washington COVID-19) Outbreak: What the Department of Radiology Should Know The incubation period of coronavirus disease 2019 (COVID-19) from publicly reported confirmed cases: estimation and application. Annals of internal medicine ACR recommendations for the use of chest radiography and computed tomography (CT) for suspected COVID-19 infection. ACR website Advocacy-and Economics/ACR-Position-Statements/Recommendations-for-Chest-Radiography-and-CTfor-Suspected-COVID19-Infection Updated ACR-SPR Practice Guideline for the Performance of Pediatric and Adult Portable (Mobile Unit) Chest Radiography Antiscatter stationary-grid artifacts automated detection and removal in projection radiography images The standardized exposure index for digital radiography: an opportunity for optimization of radiation dose to the pediatric population The validity and reliability of the exposure index as a metric for estimating the radiation dose to the patient The Phantoms of Medical and Health Physics: Devices for Research and Development Imaging Profile of the COVID-19 Infection: Radiologic Findings and Literature Review The Role of Chest Imaging in Patient Management during the COVID-19 Pandemic: A Multinational Consensus Statement from the Fleischner Society Patient dose optimization for computed radiography using physical and observer-based measurements as image quality metrics. Radiation Physics and Chemistry Perceiving and responding to challenges in job crafting at different ranks: When proactivity requires adaptivity novel coronavirus response: Strategies for ensuring healthcare systems preparedness and optimizing N95 supplies pandemic.The MT made me feel safer taking chest Xrays on patients who were suspected of having COVID-19 infection or were known positive COVID-19 patients.I was able to use less PPE when using the MT compared to the CT.The MT made it more difficult to take a portable chest X-ray in the ED compared to the CT.Most ED nurses were willing to assist with the MT (by placing the detector behind the patient).Percentage strongly agree agree neutral disagree strongly disagree