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Respiratory Gating during Stereotactic Body Radiotherapy for Lung Cancer Reduces Tumor Position Variability

By Tetsuo Saito (656390), Tomohiko Matsuyama (656391), Ryo Toya (656392), Yoshiyuki Fukugawa (656393), Takamasa Toyofuku (656394), Akiko Semba (656395) and Natsuo Oya (656396)

Abstract

<div><p>Purpose</p><p>We evaluated the effects of respiratory gating on treatment accuracy in lung cancer patients undergoing lung stereotactic body radiotherapy by using electronic portal imaging device (EPID) images.</p><p>Materials and Methods</p><p>Our study population consisted of 30 lung cancer patients treated with stereotactic body radiotherapy (48 Gy/4 fractions/4 to 9 days). Of these, 14 were treated with- (group A) and 16 without gating (group B); typically the patients whose tumors showed three-dimensional respiratory motion ≧5 mm were selected for gating. Tumor respiratory motion was estimated using four-dimensional computed tomography images acquired during treatment simulation. Tumor position variability during all treatment sessions was assessed by measuring the standard deviation (SD) and range of tumor displacement on EPID images. The two groups were compared for tumor respiratory motion and position variability using the Mann-Whitney U test.</p><p>Results</p><p>The median three-dimensional tumor motion during simulation was greater in group A than group B (9 mm, range 3–30 mm vs. 2 mm, range 0–4 mm; p<0.001). In groups A and B the median SD of the tumor position was 1.1 mm and 0.9 mm in the craniocaudal- (p = 0.24) and 0.7 mm and 0.6 mm in the mediolateral direction (p = 0.89), respectively. The median range of the tumor position was 4.0 mm and 3.0 mm in the craniocaudal- (p = 0.21) and 2.0 mm and 1.5 mm in the mediolateral direction (p = 0.20), respectively.</p><p>Conclusions</p><p>Although patients treated with respiratory gating exhibited greater respiratory tumor motion during treatment simulation, tumor position variability in the EPID images was low and comparable to patients treated without gating. This demonstrates the benefit of respiratory gating.</p></div

Topics: Biological Sciences, MethodsOur study population, Tumor Position Variability PurposeWe, EPID images, tumor position variability, gating, treatment simulation, lung cancer patients, mediolateral direction, 30 lung cancer patients, lung stereotactic body radiotherapy, mm, sd, tumor position, portal imaging device, tumor motion, Stereotactic Body Radiotherapy
Year: 2014
DOI identifier: 10.1371/journal.pone.0112824
OAI identifier: oai:figshare.com:article/1232829
Provided by: FigShare
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