Final answer:
In medical imaging, especially when using a fluoroscope with a vidicon camera, image blur or distortion caused by rapid movement is called lag. Lag results in smeared or delayed images due to the persistence of the image on the camera tube target, as opposed to vignetting or noise.
Step-by-step explanation:
When a fluoroscope utilizing a vidicon camera is moved rapidly, the resultant image blur or distortion is referred to as lag. Lag occurs when the image is smeared or blurred due to the persistence of the image on the camera tube target. This effect is akin to the blurring seen when taking a photograph with a slow shutter speed. Rapid movement causes the light sensing elements to retain the image longer than intended, causing a delay in the display of the new image position.
In comparison, vignetting is a reduction of an image's brightness or saturation at the periphery compared to the image center, and noise refers to random variations of brightness or color information in images, usually due to electronic interference or lack of light.
Understanding the concept of lag is important for professionals in medical imaging to ensure accurate diagnosis and proper functioning of imaging equipment. It is significant for maintaining high standards of patient care in the field of radiology.