Dosimetric comparison between volumetric modulated arc therapy with RapidArc and fixed-field intensity modulation radiation ther-apy for nasopharyngeal carcinoma
10.3969/j.issn.1000-8179.2015.22.025
- VernacularTitle:鼻咽癌容积调强旋转放疗和固定野适形调强放疗的剂量学对比
- Author:
Guiqiong XU
;
Zhen LI
;
Yijing YE
;
Feng LEI
;
Minying LI
;
Yuhai BAI
;
Yuxiu OUYANG
- Publication Type:Journal Article
- Keywords:
nasopharyngeal cancer;
volumetric modulated arc therapy;
intensity modulation radiation therapy
- From:
Chinese Journal of Clinical Oncology
2015;42(22):1090-1095
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To compare the dosimetric differences between volumetric modulated arc radiotherapy with RapidArc and fixed-field intensity modulation radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC), and identify the techniques from which patients of different T stages can gain the maximum benefit. Methods:Sixty non-metastatic patients with NPC were randomly selected. According to the T staging of 2008 Chinese Classification, T1-T2 stage cases were observed in 20 of the 60 patients, whereas T3 and T4 stage cases were seen with 20 patients each. RapidArc and IMRT treatment plans were managed by the Eclipse treatment planning sys-tem of Varian Co., US. The dosimetry of the target volume coverage, organs at risk (OARs), monitor unit (MU) per second, and deliv-ery time were evaluated. Results:Both techniques reached the requirement of clinical treatment. The coverages of planning target vol-ume, conformity index, and homogeneity index were similar. However, the stratified analysis of T staging indicated that RapidArc plans led to an increased dose to the tumor target (P<0.05) and an improved homogeneity index (P=0.059) in the T4 stage cases. RapidArc al-lowed a statistical dose reduction to the OARs, including optic nerves, lens, temporal lobe, V20 of the parotids, larynx, and temporo-mandibular joint (P<0.05). In the T-stage stratified analysis, the D1%and Dmax of brain stem in T1-T3 stages were similar but statistical-ly low in T4 stage in the RapidArc group (P<0.05). Compared with those in IMRT group, the MUs and the delivery time in RapidArc group were reduced by 65%and 63%, respectively. Conclusion:Both RapidArc and IMRT attained the clinical requirement for NPC. RapidArc technique showed improvements in the OARs and reduction in MUs and delivery time. The target volume coverages were similar for T1-T3 stage. However, RapidArc delivered an increased dose to the tumor target in T4 stage cases, and the dose to OARs was reduced.
