@article{oai:repo.qst.go.jp:00045320,
 author = {Islam, Amirul and Yanagi, Takeshi and Mizoe, Junetsu and Mizuno, Hideyuki and Tsujii, Hirohiko and 柳 剛 and 溝江 純悦 and 水野 秀之 and 辻井 博彦},
 issue = {7},
 journal = {Radiation Medicine},
 month = {Aug},
 note = {Purpose: A comparative treatment planning study has been performed between carbon ion radiotherapy (CIRT) and photon radiotherapy [three-dimensional conformal radiotherapy (3D-CRT) and intensitymodulated radiotherapy (IMRT)] to assess the potential improvements and limitations that could result for locally advanced, nonresectable head and neck tumors.
Materials and methods: Seven patients, originally treated with CIRT, were randomly selected for the comparative study. The evaluations analyzed using dose-volume histogram parameters, conformity index, inhomogeneity coefficient, and dose to the organs  at risk (OARs). 
Results: The mean conformity index was 1.46,1.43,and 1.22 for 3D-CRT, IMRT,and CIRT, respectively. The mean inhomogeneity coefficient was 0.05,0.07,and 0.02 for 3D-CRT, IMRT,and CIRT respectively. Photon plans resulted in greater volumes of normal tissues at 10% to 95% isodose levels compared with the corresponding carbon ion plans where the volumes increased by a factor of 1.2 to 2.7 for 3D-CRT and 1.2 to 2.0 for IMRT.
Conclusion: CIRT has the potential to improve the target dose conformity inhomogeneity coefficient, and OAR sparing when compared with 3D-CRT and IMRT. Compared with 3D-CRT, normal tissue exposure was reduced mainly in the mid-to low-isodose levels using IMRT. Additional improvement was obtained using CIRT.},
 pages = {415--421},
 title = {Comparative study of dose distribution between carbon ion radiotherapy and photon radiotherapy for head and neck tumor},
 volume = {26},
 year = {2008}
}