The impact of 4DCT-ventilation imaging-guided proton therapy on stereotactic body radiotherapy for lung cancer
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The impact of 4DCT‑ventilation imaging‑guided proton therapy on stereotactic body radiotherapy for lung cancer Yoshiro Ieko1,2 · Noriyuki Kadoya1 · Takayuki Kanai1,3 · Yujiro Nakajima1,4 · Kazuhiro Arai1,5 · Takahiro Kato5,6 · Kengo Ito1 · Yuya Miyasaka1,2 · Ken Takeda7 · Takeo Iwai2 · Kenji Nemoto2,3 · Keiichi Jingu1 Received: 20 January 2020 / Revised: 5 June 2020 / Accepted: 8 June 2020 © Japanese Society of Radiological Technology and Japan Society of Medical Physics 2020
Abstract Functional lung avoidance during radiotherapy can help reduce pulmonary toxicity. This study assessed the potential impact of four-dimensional computed tomography (4DCT)-ventilation imaging-guided proton radiotherapy (PT) on stereotactic body radiotherapy (SBRT) by comparing it with three-dimensional conformal radiotherapy (3D-CRT) and volumetric modulated arc therapy (VMAT), which employ photon beams. Thirteen lung cancer patients who received SBRT with 3D-CRT were included in the study. 4DCT ventilation was calculated using the patients’ 4DCT data, deformable image registration, and a density-change-based algorithm. Three functional treatment plans sparing the functional lung regions were developed for each patient using 3D-CRT, VMAT, and PT. The prescribed doses and dose constraints were based on the Radiation Therapy Oncology Group 0618 protocol. We evaluated the region of interest (ROI) and functional map-based dose-function metrics for 4DCT ventilation and the irradiated dose. Using 3D-CRT, VMAT, and PT, the percentages of the functional lung regions that received ≥ 5 Gy (fV5) were 26.0%, 21.9%, and 10.7%, respectively; the fV10 were 14.4%, 11.4%, and 9.0%, respectively; and fV20 were 6.5%, 6.4%, and 6.6%, respectively, and the functional mean lung doses (fMLD) were 5.6 Gy, 5.2 Gy, and 3.8 Gy, respectively. These results indicated that PT resulted in a significant reduction in fMLD, fV5, and fV10, but not fV20. The use of PT reduced the radiation to highly functional lung regions compared with those for 3D-CRT and VMAT while meeting all dose constraints. Keywords Radiotherapy · Lung cancer · Ventilation imaging · 4D-CT · Proton therapy
* Noriyuki Kadoya [email protected] 1
Department of Radiation Oncology, Tohoku University Graduate School of Medicine, 1‑1 Seiryo‑machi, Aoba‑ku, Sendai 980‑8574, Japan
2
Department of Heavy Particle Medical Science, Yamagata University Graduate School of Medical Science, Yamagata, Japan
3
Department of Radiation Oncology, Faculty of Medicine, Yamagata University, Yamagata, Japan
4
Department of Radiation Oncology, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Tokyo, Japan
5
Department of Radiation Physics and Technology, Southern Tohoku Proton Therapy Center, Koriyama, Japan
6
Preparing Section for New Facility of Medical Science, Fukushima Medical University, Fukushima, Japan
7
Department of Radiological Technology, Graduate School of Health Sciences, Faculty of Medicine, Tohoku University, Sendai, Japan
1 Introduction Lung
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