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SU‐E‐J‐151: An Off‐Line QA Tool for Evaluating Reproducibility of Deep Inhalation Breath‐Hold Treatment for Breast Radiotherapy
Author(s) -
Yang W,
Yue Y,
Mirhadi A,
Hakimian B,
Burnison M,
Tuli R,
Sandler H,
Fraass B
Publication year - 2013
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4814363
Subject(s) - spirometer , reproducibility , image guided radiation therapy , nuclear medicine , medical imaging , breathing , medicine , computer science , region of interest , artificial intelligence , medical physics , mathematics , surgery , airway , statistics , anatomy , exhaled nitric oxide , bronchoconstriction
Purpose: To develop an off‐line QA tool for evaluating reproducibility of deep inhalation breath hold (DIBH) breast treatment using a spirometer‐based breathing control system with video guidance. Methods: Tangential beam plans (open medial field; lateral IMRT field) used for whole breast radiation with DIBH‐guided by a spirometer‐based breathing control system have been studied. An imaging sequence was set‐up at the treatment machine to acquire multiple (>15) EPID image frames during beam‐on with source‐to‐imager distance 150cm. Images were exported from the EPID and imported into an off‐line QA tool developed in‐house for evaluation of intra‐and inter‐fractional uncertainties for DIBH treatments. The user defines a region of interest (ROI) (e.g., expander, clip(s), chestwall) on the first (reference) image. A rectangular imaging template is created from the ROI with a defined expansion (e.g., 1cm). The template is then matched to each of the following image frames using cross‐correlation. Template movement is used to estimate breast motion during one or multiple breath‐hold sessions. The breath‐hold lung volume information is extracted from the spirometer and compared to the corresponding motion curve estimated from the EPID images. Results: Motions of different regions of the breast can be visualized and shown to be constant within 1mm at the imager (∼.7mm in the breast) for some patients. Both drifting and random motions can be identified on individual patients on specific days. Off‐line analysis of these data may provide a useful tool to assure that individual patients are adequately performing the DIBH technique, and to identify patients who require new margins or planning strategies. Conclusion: An off‐line QA motion evaluation tool has been designed for DIBH breast treatment, and is an effective method for evaluation of DIBH reproducibility both intra‐and inter‐fraction.