ABSTRACT
Breathing motion-induced artifacts plague radiation therapy by distorting images and reducing the accuracy or conformality of dose distributions. Human breathing is a quasi-voluntary function that has a period of approximately 5 s, significantly faster than the time required to deliver radiation doses and acquire cone-beam computed tomography (CT) scans, and similar to the timescale required to acquire volumetric images using diagnostic CT scanners. Breathing can be temporarily halted for up to a minute, but many cancer patients have compromised respiratory function and cannot hold their breath. Breath hold is used effectively in diagnostic imaging, especially for modern CT scanners, which can acquire a thoracic or abdominal image data set in a few seconds. Nuclear medicine image acquisition and radiation therapy delivery require longer times, so single breath-hold times are not sufficient to remove the influence of breathing motion. There are multiple breath-hold protocols, but they require that the patient can hold their breath and comply with the instructions.
