Impact of lung tumor motion on dose delivered to organ at risk in lung stereotactic body radiation therapy
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ORIGINAL RESEARCH
Impact of lung tumor motion on dose delivered to organ at risk in lung stereotactic body radiation therapy Milovan Savanovic 1,2
&
Bojan Strbac 3 & Drazan Jaros 4 & Dejan Cazic 4 & Jean Noel Foulquier 1
Received: 1 July 2020 / Accepted: 5 November 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Purpose To evaluate the amplitude of lung tumor motion and impact of tumor motion on dose delivered to the organs at risk (OARs) during lung stereotactic body radiation therapy (SBRT). Materials and methods This study included 55 patients (30 males and 25 females) with lung cancer who had a small gross tumor volume (GTV). SBRT lung cancer patients were treated with a prescribed dose of 60 Gy in 4 to 8 fractions. Radiotherapy plans were planned in Pinnacle 9.10 with two partial dynamic conformal arcs (DCAs) for the peripheral region (PR) and three to four partial DCAs for the central region (CR). The amplitude of tumor motion and their impact on the maximum dose delivered (Dmax) to the OARs were evaluated in the upper lobe (UL) and lower lobe (LL) in cases of CR and PR tumor’s localizations. Results The median tumor motions between CR and PR were 4.5 vs 2.2 mm in the UL and 12.5 vs 7.0 mm in the LL. Max dose delivered to the OARs between CR and PR in the UL and LL were as follows: 6.7 vs 8.9 Gy and 9.1 vs 11.7 Gy for the spinal cord; 15.2 vs 0.6 Gy and 22.4 vs 7.6 Gy for the heart; and 11.7 vs 10.8 Gy and 14.8 vs 9.8 Gy for the esophagus, respectively. Conclusion The dose received by the OARs depends on the amplitude of tumor motion and is relative to the OAR’s location and motion, due to patient respiration and heart contribution. Keywords Stereotactic body radiation therapy . Lung cancer . Tumor motion . Organ at risk . Dynamic conformal arc
Introduction Lung cancer treatment depends on the stage of the disease. For patients with locally advanced disease, conventional fractionation is involved, generally using intensity modulated radiation therapy (IMRT) [1]. On the other hand, patients with early-stage lung cancer are treated with hypofractionation, using stereotactic body radiation therapy (SBRT) [2]. The stereotactic body radiation therapy (SBRT) is based on the delivery of a high dose in a single or a few fractionated * Milovan Savanovic [email protected] 1
Department of Radiation Oncology, Tenon Hospital, 75020 Paris, France
2
Faculty of Medicine, University of Paris-Saclay, 94276 Le Kremlin-Bicêtre, France
3
Physics department, MATER Private Hospital, Eccles Street, Dublin 7, Ireland
4
Affidea, International Medical Centers, Center for Radiotherapy, 78000 Banja Luka, Bosnia and Herzegovina
radiation [3]. Generally, lung SBRT treatment is prescribed for gross tumor volume (GTV) with a diameter of ≤ 5 cm, while the dose and number of fractions depend on tumor localization and proximity to the organs at risk (OARs) [4]. Utilization of high doses requires a better protection of surrounding healthy tissues during treatment planning for lung SBRT treatment
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