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Clinical Experience with Spirometer Guided Breath Hold Lung SBRT

D Wiant

H Liu , M Manning , B Sintay , J Maurer , L Hayes , D Wiant*, Cone Health Cancer Center, Greensboro, NC


SU-E-T-177 (Sunday, July 12, 2015) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: Tumor motion in lung SBRT is typically managed by creating an internal target volume (ITV) based on 4D-CT information. Another option, which may reduce lung dose and imaging artifact, is to use a breath hold (BH) during simulation and delivery. Here we evaluate the reproducibility of tumor position at repeated BH using a newly released spirometry system.
Methods: Three patients underwent multiple BH CT’s at simulation. All patients underwent a BH cone beam CT (CBCT) prior to each treatment. All image sets were registered to a patient’s first simulation CT based on local bony anatomy. The gross tumor volume (GTV), and the diaphragm or the apex of the lung were contoured on the first image set and expanded in 1 mm increments until the GTVs and diaphragms on all image sets were included inside an expanded structure. The GTV and diaphragm margins necessary to encompass the structures were recorded.
Results: The first patient underwent 2 BH CT’s and fluoroscopy at simulation, the remaining patients underwent 3 BH CT’s at simulation. In all cases the GTV’s remained within 1 mm expansions and the diaphragms remained within 2 mm expansions on repeat scans. Each patient underwent 3 daily BH CBCT’s. In all cases the GTV’s remained within a 2 mm expansions, and the diaphragms (or lung apex in one case) remained within 2 mm expansions at daily BH imaging.
Conclusions: These case studies demonstrate spirometry as an effective tool for limiting tumor motion (and imaging artifact) and facilitating reproducible tumor positioning over multiple set-ups and BH’s.

Funding Support, Disclosures, and Conflict of Interest: This work was partially supported by Qfix.

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