@misc{oai:repo.qst.go.jp:00069831,
 author = {Yamamoto, Naoyoshi and Baba, Masayuki and Nakajima, Mio and Miyamoto, Tadaaki and Kandatsu, Susumu and Yoshikawa, Kyosan and Mizoe, Junetsu and Kamada, Tadashi and Tsujii, Hirohiko and 山本 直敬 and 馬場 雅行 and 中嶋 美緒 and 宮本 忠昭 and 神立 進 and 吉川 京燦 and 溝江 純悦 and 鎌田 正 and 辻井 博彦},
 month = {Aug},
 note = {Background
Concerning the change of tumor shadow and the pulmonary response after radiotherapy for non-small cell lung cancer, a number of studies have been reported, but only few studies have been conducted base on long-term observation after radiotherapy. In order to evaluate the characteristics of changes in tumor shadow on CT images and the pulmonary response after carbon ion radiotherapy (CIRT) for non-small cell lung cancer, we examined the CT images for those with long-term local control and evaluated if there were any changes in the shadow at the tumor site on CT before and after CIRT.
Methods
In our institute, 69 patients received CIRT more than 8 years ago with a total dose of 72.0 GyE given in 9 fractions. Among them, we selected 27 cases who survived 5 years or longer and were judged as free of local recurrence, for whom changes in the shadows at the tumor site were analyzed on CT scans before and after CIRT. CT images were taken immediately after CIRT or up to 1 month, after 3–4 months, after 6–8 months, after 12 months, and every 6 months thereafter. The CT scans were performed with the slice thickness of 3 mm, the slice interval of 3 mm, the window width of 1600, and the window level of -600 to -550.
Results
The change of the shadow was categorized into four patterns: A) those in which a shadow on CT immediately after irradiation was larger than before the irradiation, thereafter continued to enlarge, and then fixed (3.7%); B) those in which the shadow became smaller on CT immediately after the irradiation and then fixed in an unchanged form (11.1%); C) those in which the shadow became smaller on CT immediately after the irradiation, then the shadow temporarily enlarged, and again the shadow became smaller and fixed (18.5%); and D) those in which the shadow became smaller on CT immediately after the irradiation, then the shadow temporarily enlarged, thereafter fixed in an unchanged form (66.7%).
Regarding the aforementioned changes of the shadow, it was an average of 11.2 months (2.0–36.5 months) after CIRT when the tumor shadow and a pneumonitis shadow merged to form a larger shadow. Furthermore, the period until the shadow became smaller or the period until shadow enlargement was no longer found averaged 15.4 months (4.7–46.7 months) after the CIRT. In 23 of 27 cases (85.2%), the shadow was fixed within 2 years; while in the remaining 4 cases, the shadow was fixed within 2 to 4 years. In 18 cases (66.7%), the size of the fixed shadow was larger than that of the tumor before CIRT.
Conclusions
In most cases examined, the changes in the shadows on CT tended to fix within 2 years after CIRT. This finding appeared useful for estimating the local control in the follow-up after CIRT., 13th World Conference on Lung Cancer},
 title = {Serial radiographic changes on CT for long survivors after carbon ion radiotherapy in non-small cell lung cancer},
 year = {2009}
}