New opportunities for the use of digital video in on-line radiologic curricula

To explore techniques to conveniently and self-sufficiently create high-quality, web-ready instructional digital video snippets suitable for routine use in on-line radiologic curricula.

A commercially available digital camera with an 8-megapixel image receptor and the capability to record web-ready digital video and audio at a resolution of up to 640 x 480 pixels and a frame rate of up to 30 per second was used to obtain video snippets intended for inclusion in on-line curricula. Hand-held and tripod techniques were compared. Evaluation focused on the types of snippets deemed most likely to be used within on-line educational content, ranging in length from 10 seconds to 2 minutes. Additionally, basic postprocessing functions to experiment with combinations of video-file size, format, transmission efficiency, and image quality were used.

The overall video quality was considered by participating radiologists to be good to excellent for its intended purposes. For most situations tested, a matrix size of 320 x 240 pixels provided a good balance of visual quality versus file size and transmission overhead. The 640 x 480 format was occasionally optimal, but was usually larger than necessary and resulted in substantially larger files, especially at a rate of 30 frames per second. A rate of 15 frames per second was considered adequate for most situations, regardless of matrix size, although it did add some barely discernible choppiness to the display. For all but very short snippets, a tripod or some other form of stabilization was necessary to eliminate distracting "camera shake" associated with free-hand acquisition. With a tripod, appropriate ambient lighting, and a favorable acoustical environment, videos of excellent quality when using the highest settings available on the camera (640 x 480, 30 frames/sec) could be self-sufficiently produced. However, such high-quality video with its associated large file size was rarely the optimal fit for the needs of this curricula.

These results indicate that newer-generation digital cameras are useful for quickly and inexpensively producing high-quality, web-ready digital video suitable for use in on-line education.