Ⅲ期非小細胞肺癌に対するIMRT：知っておきたいポイント

Intensity modulated radiation therapy for stage Ⅲ non-small cell lung cancer：merits and considerations

Ⅲ期非小細胞肺癌に対する放射線治療において強度変調放射線治療（intensity-modulated radiation therapy：IMRT）の普及が進んでいる。IMRTのメリットとして，① 放射線肺臓炎や心血管毒性の軽減による治療関連死亡の減少，② 放射線食道炎の減少による治療コンプライアンスの向上，③ 適応患者の拡大，すなわち正常肺への線量制約が従来の3次元放射線治療（3D conformal radiation therapy：3D-CRT）では達成できず根治照射が困難な場合でもIMRTでは根治照射が可能となる場合がある，などがある。

The use of intensity modulated radiation therapy is prevailing in the treatment of stage Ⅲ non-small cell lung cancer. It can reduce toxicities for the lung, the heart, and the esophagus leading to less treatment related death, better treatment compliance, and finally improved overall survival. Many considerations are needed compared to three-dimensional conformal radiation therapy in the treatment planning stage such as target definition, dose constraints for the lung and the heart, and treatment prescription methods. Standardization of treatment planning with education opportunity are necessary for further prevalence of high-quality intensity modulated radiation therapy.