A digital video capture system that integrates seamlessly into an existing Electronic Patient Record infrastructure was developed to improve the documentation of endoscopic procedures. Still images are sent to the PACS (Picture Archiving and Communication system), and videos are sent to a web review application. A standard clinical desktop application is used to unify the review of all patient records, including captured still and video images.
The documentation of endoscopic procedures has traditionally been limited to text-based narratives and descriptions of findings. The use of video printers and video tape recorders can greatly improve the comprehensiveness of the procedure record, but are ultimately impractical due to difficulty of storage and retrieval. Digital video however, eliminates some of the impracticalities normally associated with the storage and review of full-motion videotape. Digital video, through the use of databases, networks and mass storage devices, can eliminate the need to physically store videotapes. The random access nature of digital video allows for quick access to point of interest when compared to the sequential access of videotape. Ultimately, integration into an electronic patient record (EPR) would necessitate the digitization of video for large-scale storage and distribution.
To develop a digital endoscopic video system that integrates seamlessly into an existing EPR infrastructure.
While still images can be incorporated into a PACS (Picture Archiving and Communication System) using the well-established DICOM standard used in medical imaging informatics, DICOM does not support interframe compression schemes which most digital video codecs use. As the result, captured videos are stored in a separate database, and a web based application for reviewing the videos was developed. The choice of video codec amongst the dozens available was chosen such that it must produce video of sufficient quality for diagnoses, but also allow a level compression such that the data rate will not burden network and storage resources. MPEG-1 was found to be flexible enough for the application and also benefited from its native integration into all major operating systems. A validation was performed to confirm that diagnostic quality was achieved at an optimum data rate for storage and retrieval. The validation process suggested that MPEG-1 video at data rates as low as 1.5 Mbps at a 352 by 240 pixel (NTSC – Source Input Format) resolution is of acceptable quality for the documentation of colonoscopy. At the 1.5 Mbps data rates described, the file size for captured and encoded video run about 12 Mbytes per minute. This is manageable for most modest networks and data archives. Real-time encoding from the endoscope processor output is achieved using an Optibase real-time MPEG-1 encoder card running on Windows 2000 PC platform. A custom HL-7 interface and LCD touch-screen are used to associate patient information with captured video. The capture start, stop and continue events are initiated via footswitches. Voice annotation of the video can be achieved via a wireless headset microphone system as the video is captured. Still images can also be acquired as video is being captured, as the system uses independent video capture cards. The MPEG-1 digital video is then transferred over a 100 Mbps Ethernet network to a server for storage and later retrieval. The video can be reviewed through a web-based Active Server Page (ASP) application utilizing the Windows Media Player’s MPEG-1 decoder. This web application is incorporated as part of a standard clinical desktop application in which other clinical data such as lab results, xray, and endoscopy capture still images can be reviewed with a single secure login.
Voice-annotated digital video provides a more comprehensive endoscopic patient record. A standard protocol for the electronic management of medical digital video is necessary for interoperability of systems and simplified EPR integration. Through the appropriate development and evaluation of information technology to manage visual information, endoscopists will be able to improve patient care, teaching, and research.
Medical Device Informatics Group, Departments of Medicine and Medical Engineering, Centre of Global eHealth Innovation, University Health Network
Faculty of Medicine and the Institute of Biomaterials and Biomedical Engineering, University of Toronto