Monitoring ABC-assisted deep inspiration breath hold for left-sided breast radiotherapy with an XXXX .

@entity1 @entity1781 @entity1370 @entity0
PURPOSE: Recent knowledge on the effects of @entity1370 warrants greater precision for left-sided breast radiotherapy. Different breath-hold (BH) maneuvers (abdominal vs thoracic breathing) can lead to chest wall positional variations, even though the @entity1 's tidal volume remains consistent. This study aims to investigate the feasibility of using optical tracking for real-time quality control of active breathing coordinator (ABC)-assisted deep inspiration BH (DIBH). METHODS: An in-house @entity1781 ( @entity1781 ) was used to monitor ABC-assisted DIBH. The stability and localization accuracy of the @entity1781 were assessed with a ball-bearing phantom. Seven @entity1 with left-sided @entity0 were included. A free-breathing (FB) computed tomography (CT) scan and an ABC-assisted BH CT scan were acquired for each @entity1 . The @entity1781 tracked an infrared (IR) marker affixed over the @entity1 's xiphoid process to measure the positional variation of each individual BH. Using the BH within which the CT scan was performed as the reference, the authors quantified intra- and interfraction BH variations for each @entity1 . To estimate the dosimetric impact of BH variations, the authors studied the positional correlation between the marker and the left breast using the FB CT and BH CT scans. The positional variations of 860 BHs as measured by the @entity1781 were retrospectively incorporated into the original treatment plans to evaluate their dosimetric impact on breast and cardiac organs [heart and left anterior descending (LAD) artery]. RESULTS: The stability and localization accuracy of the @entity1781 was within 0.2 mm along each direction. The mean intrafraction variation among treatment BHs was less than 2.8 mm in all directions. Up to 12.6 mm anteroposterior undershoot, where the @entity1 's chest wall displacement of a BH is less than that of a reference BH, was observed with averages of 4.4, 3.6, and 0.1 mm in the anteroposterior, craniocaudal, and mediolateral directions, respectively. A high positional correlation between the marker and the breast was found in the anteroposterior and craniocaudal directions with respective Pearson correlation values of 0.95 and 0.93, but no mediolateral correlation was found. Dosimetric impact of BH variations on breast coverage was negligible. However, the mean heart dose, mean LAD dose, and max LAD dose were estimated to increase from 1.4/7.4/18.6 Gy (planned) to 2.1/15.7/31.0 Gy (delivered), respectively. CONCLUSIONS: In ABC-assisted DIBH, large positional variation can occur in some @entity1 , due to their different BH maneuvers. The authors' study has shown that @entity1781 can be a valuable tool for real-time quality control of ABC-assisted DIBH.
