[Evaluation of jaws-only intensity-modulated radiation therapy for nasopharyngeal carcinoma].
OBJECTIVE
To investigate the feasibility and efficiency of jaws-only intensity-modulated radiation therapy (JO-IMRT) in treatment of nasopharyngeal carcinoma (NPC) using direct aperture optimization (DAO) technique and the independent jaws of linear accelerator.


METHODS
Both JO-IMRT and MLC-IMRT were planed in 10 NPC cases. The differences in the target coverage and dose uniformity, as well as the total monitor units and delivery times of the two IMRT plans were compared.


RESULTS
All the tested plans met the clinical requirement of the designed simplified IMRT (sIMRT). The conformal index (CI) of JO-IMRT and MLC-IMRT were 0.941±0.015 and 0.981±0.013, respectively (P<0.001), showing a minor superiority of MLC-IMRT. While controlling the total segment numbers to approach the limitation of sIMRT, the two therapies showed a total MU of 474.3 and 419.6 (P<0.05) with delivery times of 8.0 and 7.5 min (P<0.01), respectively. The efficiency of JO-IMRT was slightly lower than that of MLC-IMRT.


CONCLUSIONS
JO-IMRT can meet the sIMRT requirement in NPC treatment, and is feasible as an alternative treatment modality for the centers not equipped with MLC in their accelerators.
State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou 510060, China. huangshm@sysucc.org.cn
Shao-min
SM
Huang
Xing-wang
XW
Gao
Xiao-wu
XW
Deng
Shi
S
Wang
D002277:Carcinoma; D005240:Feasibility Studies; D006801:Humans; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D010315:Particle Accelerators; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*