@misc{oai:repo.qst.go.jp:00067395,
 author = {Hasegawa, Azusa and Mizoe, Junetsu and Tsujii, Hirohiko and Hasegawa, Shogo and 長谷川 安都佐 and 溝江 純悦 and 辻井 博彦 and 長谷川 正午},
 month = {Jun},
 note = {PURPOSE: To analyze the prognostic factor in late morbidity of visual acuity in carbon ion radiotherapy for head and neck cancer. 
     METHODS AND MATERIALS: Between June 1994 to March 2000, 163 patients with head and neck tumor were treated with carbon ions. Selected for this study were 30 patients (54 optic nerves (ONs) ), whose ONs with the primary tumor were included in high dose area, who had no evidence of visual impairment before radiotherapy, and who had follow up period more than 2 years. The median age of 30 patients was 57.2 years with 14 males and 16 females. Median prescribed total dose was 56.0 gray equivalent (GyE) (range, 48-64 GyE). Age, gender, KI, anemia, blood pressure and dose of ONs were listed as prognostic factors. The dose of ONs was delivered from DVHs calculated from planning CT. All patients were informed the possibility of visual impairment before treatment. 
     RESULTS: Eleven ONs showed decrease of visual acuity at an average of 19.6-month and eventually progressed to visual loss at 25.6-month after irradiation. All of them, the ONs were involved within tumor. Thereby, it was unavoidable to exclude a part of or all ON from the PTV. Median maximum dose of the ON was 49.6GyE. Thirty-four ONs irradiated by less than 56 GyE (maximum-dose) resulted in no visual impairment. On the other hand, in 20 ONs irradiated by more than 56 GyE, a decrease of visual acuity was observed in 11 ONs (55%). Multivariate analysis revealed anemia and D0.30 as unfavorable prognostic factors.
CONCLUSION: None of the unexpected morbidity had been observed in this treatment. The dose-complication probability of visual acuity in carbon ion radiotherapy was confirmed in this study. The data suggested that D0.30 was a good predictor for the tolerance dose., International Stereotactic Radiosurgery Society Congress},
 title = {Outcom of visual acuity in carbon ion radiotherapy-Analysis of the DVHs and prognostic factor-},
 year = {2003}
}