Program Information
Dosimetric Comparison Between Inverse Modulated Techniques and Conformal Arcs in the Stereotactic Treatment of Lung Lesions
A Bejarano Buele*, S Bradley , A Lisher , Lawrence Cancer Center, Lawrence, KS
Presentations
TU-C1-GePD-T-6 (Tuesday, August 1, 2017) 9:30 AM - 10:00 AM Room: Therapy ePoster Lounge
Purpose: The precise and effective ablation of small lesions in SBRT/SRS modalities depends on various factors, which include the planning technique used for treatment. The purpose of this study is to dosimetrically compare IMRT and Conformal Arc techniques in the stereotactic treatment of lung lesions.
Methods: This study includes datasets of 10 patients with lung lesions treated with SBRT (50 Gy in 5 fractions). IMRT and Conformal Arc plans were made for each dataset. The plans were optimized for an accelerator equipped with Millennium 120 MLCs, and beam energy of 6 MV. The comparison was quantified through various dosimetric parameters including a Conformity Index (CI), Paddick’s Conformity Index, Normal Tissue Differential (IMRT-Arcs), and a Gradient Index (GI). A T-test was performed to determine significant differences between the two datasets.
Results: The PTV parameters such as minimum, mean, maximum dose and hotspot are comparable in both plans as well as the CI and Paddick’s CI. The NTD had a value of positive 10.52, indicating a larger volume of tissue being irradiated by 50% IDL in IMRT plans. IMRT plans obtained an average GI of 4.43, while the average GI for Conformal Arc plans was 3.75. These values were significantly different by a p-value of <0.05.
Conclusion: IMRT and Conformal Arc plans offer similar coverage and hotspot in small lesions for SBRT. However, Conformal Arc plans show a sharper gradient with a significant difference from that offered by IMRT techniques. Conformal Arc plans not only offer greater tissue sparing, but also shorter treatment times.
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