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Observer Performance Evaluation of a Digital Camera for Acquiring Radiographic Images for Teleradiology Elizabeth A. Krupinski, PhD University of Arizona
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Goal w Conduct a feasibility study to determine if a commercially available digital camera can be used to acquire photographs of radiologic images to transmit them via store-forward technology over a telemedicine network.
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Arizona Telemedicine Program (ATP)Sites Tuba City Kingman Cottonwood Ganado Payson Springerville Whiteriver DOC - Phoenix DOC - Yuma Nogales Patagonia Douglas AHSC Kino Tucson VA AHSC Hub Telemedicine Telepathology Teleradiology DOC - Florence DOC - Buckeye DOC - Douglas
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Study Rationale w Teleradiology is an important part of an increasing number of Radiology & Telemedicine programs w Saves time and feedback to referring clinician is faster than with other methods (e.g., courier) - 85% of our teleradiology cases have a “wet read” report generated within 6 hours
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Rationale Continued w It can, however, be expensive! w For digital modalities a merge box is needed w For plain film a digitizer or video capture system is required w Some sites just cannot afford these options w A low-cost alternative had to be explored
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The Test Site w The Patagonia Family Health Center in rural Arizona needed consults, especially in orthopedics & bone radiology w The clinic has no x-ray facilities so sends patients to Nogales’ Mariposa Clinic, the report & films are then sent over either with the patients or later w Problem - Mariposa only has a general radiologist so sub-specialty consults are often required
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The Camera Canon PowerShot600 CCD image sensor 832 x 608 pixels 24-bit color resolution f/2.5 lens Built-in flash 150 kB file size
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The Cases w 40 bone trauma cases (e.g., fracture, subluxation, soft tissue damage) from the Patagonia Family Health Clinic w Cases that required a consult in the past & were representative of the types of cases they would be sending for teleconsults in the future - typically subtle lesions
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The Photographs w Film images were placed on standard viewbox with extraneous light blocked out w The physician identified region(s) of interest based on clinical history and nature of problem w At least one global and one close up shot were acquired for each image using the Canon PowerShot camera
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The Displays w Images sent over ARTN to the MedVision workstation w Color monitor, 1024 x 768 pixels w Window/level, zoom/pan available for use during viewing w Film images displayed on standard viewbox
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Example of a Close-Up Shot
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Example of an Original Film Image
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Photographed Image on the Monitor
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Protocol w 2 orthopedic surgeons & 2 bone radiologists reviewed the 40 cases on film & using the digital photographs displayed on the monitor w Film reading 6 months after monitor reading w Reported: Diagnosis Decision confidence using 6-level scale Image quality using 4-level scale
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Results - Image Quality
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2 = 20.32, df = 9, p = 0.02 w 9 of the photo cases were rated poor 4 film cases were rated poor w Of the 9 photo cases, 4 (45%) were rated as poor because the region-of-interest was not captured sufficiently w Some views (film & photo) were not what the readers were used to - different technologists
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Results - Diagnoses* ReaderAgreement (Kappa)* 10.89 20.92 30.94 40.88 * Agreement with truth. Truth was determined from the film images by 2 radiologists not participating in the study.
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Results - Confidence * How many categories film & monitor confidences differ by - a difference of two is considered significant
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Conclusions w A digital still camera can be used effectively to capture images of bone trauma radiographs for store-forward telemedicine consults w Well-framed close-up shots of the region-of- interest are essential w Good quality original films are essential
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Other Applications? w Other non-screening applications where a specific suspicious region-of-interest can be identified for close-up photographs w Unless the lesion is fairly gross, the global shots are not adequate for consultation - close-up shots are required in the majority of cases
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