Investigation of approaches for internal target volume definition using 4-dimensional computed tomography in stereotactic body radiotherapy of lung cancer.

Autor: Koksal C; Division of Medical Physics, Istanbul University Oncology Institute, Istanbul, Turkey. Electronic address: canankksal@gmail.com., Donmez Kesen N; Division of Medical Physics, Istanbul University Oncology Institute, Istanbul, Turkey., Okutan M; Division of Medical Physics, Istanbul University Oncology Institute, Istanbul, Turkey., Karaman S; Division of Radiation Oncology, Istanbul University Medical Faculty, Istanbul, Turkey., Dagoglu Sakin N; Division of Radiation Oncology, Istanbul University Medical Faculty, Istanbul, Turkey., Bilge H; Division of Medical Physics, Istanbul University Oncology Institute, Istanbul, Turkey.
Jazyk: angličtina
Zdroj: Medical dosimetry : official journal of the American Association of Medical Dosimetrists [Med Dosim] 2021 Summer; Vol. 46 (2), pp. 136-142. Date of Electronic Publication: 2020 Oct 27.
DOI: 10.1016/j.meddos.2020.10.004
Abstrakt: The present study was undertaken to investigate the suitability of alternative internal target volume (ITV) delineation strategies based on maximum intensity projection (MIP), average intensity projection (AIP), 2 extreme phases and 4 phases images relative to the ITV 10phase in stereotactic body radiation therapy (SBRT) for lung cancer. The 4-dimensional computed tomography (4DCT) data of 15 lung cancer patients treated with SBRT in our clinic were used. Five different ITVs were generated as follows: merging GTVs from 10 phases (ITV 10Phase ); merging GTVs from 2 extreme phases (0%, 50%) (ITV 2Phase ); merging GTVs from 4 phases (0%, 20%, 50%, and 70%) (ITV 4Phase ); delineating GTV on MIP (ITV MIP ), and delineating GTV on AIP (ITV AIP ). PTV 10Phase , PTV 2Phase , PTV 4Phase , PTV MIP , and PTV AIP were generated by adding a 5-mm margin around the related ITV. Volumetric analyses were performed for 4 ITVs and PTVs relative to ITV 10phase and PTV 10phase . SBRT plans made for all PTVs were evaluated for dosimetric effect of alternative ITV delineation strategies. The mean percentage overlap volume (POV) for PTV 2phase, PTV 4phase , PTV MIP , and PTV AIP relative to PTV 10phase were 84.2 ± 5.4%, 92.0 ± 2.9%, 82.2 ± 5.7%, and 73.8 ± 9.3%, for lower-lobe tumors, respectively. The mean POV for PTV 2phase, PTV 4phase , PTV MIP , and PTV AIP relative to PTV 10phase were 93.2 ± 2.5%, 95.9 ± 1.0%, 87.5 ± 6.7%, and 83.3 ± 6.8% for upper-lobe, respectively. For lower-lobe tumors the mean differences in V20 and MLD for plans based on PTV 2phase and PTV 4phase were <0.5% and <10 cGy, compared with a plan based on PTV 10phase . The use of PTV based on 4 respiratory phases and a 5-mm margin is a safe approach to reduce the workload of target delineation for tumors located in both lower and upper lobes.
(Copyright © 2020 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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