Carotid sparing intensity modulated radiotherapy on early glottic cancer: preliminary study.
OBJECTIVE
To compare the dose distribution between carotid sparing intensity modulated radiotherapy (IMRT) and opposed lateral field technique (LAFT), and to determine the effects of carotid sparing IMRT in early glottic cancer patients who have risk factors for atherosclerosis.


METHODS
Ten early glottic cancer patients were treated with carotid sparing IMRT. For each patient, the conventional LAFT plan was developed for comparison. IMRT and LAFT plans were compared in terms of planning target volume (PTV) coverage, conformity index, homogeneity index, and the doses to planning organ at risk volume (PRV) for carotid arteries, spinal cord and pharyngeal constrictor muscle.


RESULTS
Recurrence was not observed in any patients during the follow-up period. V95% for PTV showed no significant difference between IMRT and LAFT plans, while V100% was significantly higher in the IMRT plan (95.5% vs. 94.6%, p = 0.005). The homogeneity index (11.6%) and conformity index (1.4) in the IMRT plan were significantly better than those in the LAFT plans (8.5% and 5.1, respectively) (p = 0.005). The median V5Gy (90.0%), V25Gy (13.5%), and V50Gy (0%) for carotid artery PRV in the IMRT plan were significantly lower than those in the LAFT plan (99.1%, 89.0%, and 77.3%, respectively) (p = 0.005).


CONCLUSIONS
Our study suggests that carotid sparing IMRT can significantly decrease the dose to carotid arteries compared to LAFT, and it would be considered for early glottic cancer patient with high risk of atherosclerosis.
Department of Radiation Oncology, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine, Jinju, Korea.
Hoon Sik
HS
Choi
Department of Radiation Oncology, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine, Jinju, Korea.; Institute of Health Science, Gyeongsang National University, Jinju, Korea.
Bae Kwon
BK
Jeong
Department of Radiation Oncology, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine, Jinju, Korea.; Institute of Health Science, Gyeongsang National University, Jinju, Korea.
Hojin
H
Jeong
Department of Radiation Oncology, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine, Jinju, Korea.; Institute of Health Science, Gyeongsang National University, Jinju, Korea.
Jin Ho
JH
Song
Institute of Health Science, Gyeongsang National University, Jinju, Korea.; Department of Otorhinolaryngology, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine, Jinju, Korea.
Jin Pyeong
JP
Kim
Institute of Health Science, Gyeongsang National University, Jinju, Korea.; Department of Otorhinolaryngology, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine, Jinju, Korea.
Jung Je
JJ
Park
Institute of Health Science, Gyeongsang National University, Jinju, Korea.; Department of Otorhinolaryngology, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine, Jinju, Korea.
Seung Hoon
SH
Woo
Department of Radiation Oncology, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine, Jinju, Korea.; Department of Otorhinolaryngology, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine, Jinju, Korea.
Ki Mun
KM
Kang
Carotid arteries; Glottic cancer; Intensity-modulated radiotherapy