Beschreibung:
<jats:title>Abstract</jats:title><jats:p>An Active Breathing Coordinator (<jats:styled-content style="fixed-case">ABC</jats:styled-content>) can be employed to induce breath‐holds during <jats:styled-content style="fixed-case">CT</jats:styled-content> imaging and radiotherapy of lung, breast and liver cancer, and recently during lung cancer <jats:styled-content style="fixed-case">MRI</jats:styled-content>. The apparatus measures and controls respiratory volume, hence subject lung volume reproducibility is its principal measure of effectiveness. To assess <jats:styled-content style="fixed-case">ABC</jats:styled-content> control quality, the intra‐session reproducibility of <jats:styled-content style="fixed-case">ABC</jats:styled-content>‐induced lung volumes was evaluated and compared with that reached by applying the clinical standard of operator‐guided self‐sustained breath‐holds on healthy volunteers during <jats:styled-content style="fixed-case">MRI</jats:styled-content>. Inter‐session reproducibility was investigated by repeating <jats:styled-content style="fixed-case">ABC</jats:styled-content>‐controlled breath‐holds on a second visit. Additionally, lung volume agreement with <jats:styled-content style="fixed-case">ABC</jats:styled-content> devices used with different imaging modalities in the same institution (<jats:styled-content style="fixed-case">MR</jats:styled-content>,<jats:styled-content style="fixed-case"> CT</jats:styled-content>), or for a breast trial treatment, was assessed. Lung volumes were derived from three‐dimensional (3D) T1‐weighted <jats:styled-content style="fixed-case">MRI</jats:styled-content> datasets by three observers employing semiautomatic lung delineation on a radiotherapy treatment planning system. Inter‐observer variability was less than 6% of the delineated lung volumes. Lung volume agreement between the different conditions over all subjects was investigated using descriptive statistics. The <jats:styled-content style="fixed-case">ABC</jats:styled-content> equipment dedicated for <jats:styled-content style="fixed-case">MR</jats:styled-content> application exhibited good intra‐session and inter‐session lung volume reproducibility (1.8% and 3% lung volume variability on average, respectively). <jats:styled-content style="fixed-case">MR</jats:styled-content>‐assessed lung volumes were similar using different <jats:styled-content style="fixed-case">ABC</jats:styled-content> equipment dedicated to <jats:styled-content style="fixed-case">MR</jats:styled-content>,<jats:styled-content style="fixed-case"> CT</jats:styled-content>, or breast radiotherapy. Overall, lung volumes controlled by the same or different <jats:styled-content style="fixed-case">ABC</jats:styled-content> devices agreed better than with self‐controlled breath‐holds, as suggested by the average <jats:styled-content style="fixed-case">ABC</jats:styled-content> variation of 1.8% of the measured lung volumes (99 <jats:styled-content style="fixed-case">mL</jats:styled-content>), compared to the 4.1% (226 <jats:styled-content style="fixed-case">mL</jats:styled-content>) variability observed on average with self‐sustained breath‐holding.</jats:p>