SU-FF-T-563: Dosimetric Impact of Five Tumor Delineation Strategies in Stereotactic Body Radiation Therapy for Lung Cancer

Autor: A. Srisuthep, J Wu, C. Betzing, Martin Fuss
Rok vydání: 2009
Předmět:
Zdroj: Medical Physics. 36:2654-2654
ISSN: 0094-2405
DOI: 10.1118/1.3182061
Popis: Purpose: The goal of this study was to examine the dosimetric impact of five different tumor delineation strategies in stereotactic body radiation therapy(SBRT) for lungcancer patients. Methods and Materials: Seven patients who had previously undergone SBRT for lungcancer were retrospectively investigated. For each patient, a free breathing (FB) CT and a 4DCT were acquired. Based on the 4DCT scans, three post‐processing CTimages were reconstructed: maximum intensity projection (MIP), average intensity projection (AIP), and slow‐CT (SCT) images. The gross target volumes (GTVs) were delineated on the following CTimagedata sets: GTVFB on FB CT, GTV0%, GTV10%, …, GTV90% on 4DCT, GTVMIP on MIP CT, GTVAIP on AIP CT, and GTVSCT on SCT. The GTVs delineated on the 4DCT were combined to create the internal target volume (ITV). Five SBRT treatment plans were created on the FB CTimage based on the tumor delineated above: GTVFB, ITV, GTVMIP, GTVAIP, and GTVSCT. For each plan, the 4D dose was calculated using deformable‐image registration. Results: On average the tumor D100 (minimum dose received by 100% of the tumor) of the ITV and GTVMIP based plans is 3.0±4.0Gy (p=0.09) and 0.9±4.5Gy (p=0.61) respectively above that of the GTVFB based plan. While the tumor D100 of the GTVAIP and GTVSCT based plans is 2.8±6.0Gy (p=0.26) and 0.8±4.1Gy (p=0.61) below that of the GTVFB based plan respectively. Compared with the GTVFB based plan, total lung V20 of the ITV based plan is 0.4±1.0% (p=0.36) absolute higher, while that of the GTVMIP, GTVAIP, and GTVSCT based plans is 0.5±0.7% (p=0.09), 0.4±0.7% (p=0.17), and 0.2±0.5% (p=0.44) absolutely lower respectively. Conclusions: All plans can deliver equally well dose coverage to the tumor. The difference in lungdose among the five plans is also significantly small.
Databáze: OpenAIRE
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