6 research outputs found
Three-dimensional tumor respiratory motion during treatment simulation evaluated with four-dimensional CT.
<p>Three-dimensional tumor respiratory motion during treatment simulation evaluated with four-dimensional CT.</p
Respiratory Gating during Stereotactic Body Radiotherapy for Lung Cancer Reduces Tumor Position Variability
<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 β§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 3β30 mm vs. 2 mm, range 0β4 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- (pβ=β0.24) and 0.7 mm and 0.6 mm in the mediolateral direction (pβ=β0.89), respectively. The median range of the tumor position was 4.0 mm and 3.0 mm in the craniocaudal- (pβ=β0.21) and 2.0 mm and 1.5 mm in the mediolateral direction (pβ=β0.20), 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
Standard deviation (SD) of the tumor position on electronic portal imaging device (EPID) images.
<p>Each point represents a single patient's SD of the tumor position during all treatment sessions. CC β=β craniocaudal; ML β=β mediolateral.</p
Variability assessment for each patient.
<p>Variability was assessed by determining the standard deviation (SD) and range of the tumor position during all sessions.</p
Range of the tumor position on electronic portal imaging device (EPID) images.
<p>Each point represents a single patient's range of the tumor position during all treatment sessions. CC β=β craniocaudal; ML β=β mediolateral.</p
Tumor displacement measured with reference to the first EPID image acquired at the first session.
<p>EPID β=β electronic portal imaging device.</p