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SU‐FF‐T‐563: Dosimetric Impact of Five Tumor Delineation Strategies in Stereotactic Body Radiation Therapy for Lung Cancer
Author(s) -
Wu J,
Betzing C,
Srisuthep A,
Fuss M
Publication year - 2009
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 - 10.1118/1.3182061
Subject(s) - maximum intensity projection , nuclear medicine , lung cancer , radiation therapy , medicine , dosimetry , image registration , medical imaging , radiation treatment planning , lung , projection (relational algebra) , pinnacle , radiology , computer science , angiography , oncology , algorithm , artificial intelligence , image (mathematics)
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 lung cancer patients. Methods and Materials: Seven patients who had previously undergone SBRT for lung cancer were retrospectively investigated. For each patient, a free breathing (FB) CT and a 4DCT were acquired. Based on the 4DCT scans, three post‐processing CT images 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 CT image data sets: GTV FB on FB CT, GTV 0% , GTV 10% , …, GTV 90% on 4DCT, GTV MIP on MIP CT, GTV AIP on AIP CT, and GTV SCT 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 CT image based on the tumor delineated above: GTV FB , ITV, GTV MIP , GTV AIP , and GTV SCT . 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 GTV MIP based plans is 3.0±4.0Gy (p=0.09) and 0.9±4.5Gy (p=0.61) respectively above that of the GTV FB based plan. While the tumor D100 of the GTV AIP and GTV SCT based plans is 2.8±6.0Gy (p=0.26) and 0.8±4.1Gy (p=0.61) below that of the GTV FB based plan respectively. Compared with the GTV FB based plan, total lung V20 of the ITV based plan is 0.4±1.0% (p=0.36) absolute higher, while that of the GTV MIP , GTV AIP , and GTV SCT 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 lung dose among the five plans is also significantly small.