Dosimetric comparison of five different radiotherapy treatment planning approaches for locally advanced non‐small cell lung cancer with sequential plan changes

• Published in: Thoracic cancer Vol. 14; no. 35; pp. 3445 - 3452
• Main Authors: Saito, Masahide, Komiyama, Takafumi, Marino, Kan, Aoki, Shinichi, Akita, Tomoko, Matsuda, Masaki, Sano, Naoki, Suzuki, Hidekazu, Koji, Ueda, Nemoto, Hikaru, Onishi, Hiroshi
• Format: Journal Article
• Language: English
• Published: Melbourne John Wiley & Sons Australia, Ltd 01.12.2023; Wiley
• Subjects: 3DCRT; IMRT; lung cancer; Original; radiotherapy; VMAT; lung cancer; radiotherapy; VMAT; 3DCRT; IMRT
• ISSN: 1759-7706; 1759-7714
• DOI: 10.1111/1759-7714.15137

Background The purpose of this study was to compare the dosimetric characteristics of five different treatment planning techniques for locally advanced non‐small cell lung cancer (LA‐NSCLC) with sequential plan changes. Methods A total of 13 stage III NSCLC patients were enrolled in this study. These patients had both computed tomography (CT) images for initial and boost treatment plans. The latter CT images were taken if tumor shrinkage was observed after 2 weeks of treatment. The prescription dose was 60 Gy/30 Fr (initial: 40 Gy/20 Fr, and boost: 20 Gy/10 Fr). Five techniques (forward‐planed 3‐dimensional conformal radiotherapy [F‐3DCRT] on both CT images, inverse‐planned 3DCRT [I‐3DCRT] on both CT images, volumetric modulated arc therapy [VMAT] on both CT images, F‐3DCRT on initial CT plus VMAT on boost CT [bVMAT], and hybrid of fixed intensity‐modulated radiotherapy [IMRT] beams and VMAT beams on both CT images [hybrid]) were recalculated for all patients. The accumulated doses between initial and boost plans were compared among all treatment techniques. Results The conformity indexes (CI) of the planning target volume (PTV) of the five planning techniques were 0.34 ± 0.10, 0.57 ± 0.10, 0.86 ± 0.08, 0.61 ± 0.12, and 0.83 ± 0.11 for F‐3DCRT, I‐3DCRT, VMAT, bVMAT, and hybrid, respectively. In the same manner, lung volumes receiving >20 Gy (V20Gy) were 21.05 ± 10.56%, 20.86 ± 6.45, 19.50 ± 7.38%, 19.98 ± 10.04%, and 17.74 ± 7.86%. There was significant improvement about CI and V20Gy for hybrid compared with F‐3DCRT (p < 0.05). Conclusion The IMRT/VMAT hybrid technique for LA‐NSCLC patients improved target CI and reduced lung doses. Furthermore, if IMRT was not available initially, starting with 3DCRT might be beneficial as demonstrated in the bVMAT procedure of this study. The study examined five planning techniques for advanced lung cancer, evaluating dosimetric traits with plan changes and extensions. It found plan changes useful for target alterations, but a single re‐planning in offline‐adaptive radiotherapy might not minimize lung dose adequately. The IMRT/VMAT hybrid showed enhanced conformity and lower lung doses, and starting with 3DCRT is recommended if IMRT is not available initially.