周围型肺癌并纵隔淋巴结转移放疗中分野锁定准直器调强计划对肺组织保护的研究

doi:10.3760/cma.j.issn.1004-4221.2017.03.015

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Abstract Objective To retrospectively design an intensity-modulated radiotherapy (IMRT) plan with split field and fixed jaw techniques for peripheral lung cancer with mediastinal lymph node metastasis, to compare dosimetric characteristics between the IMRT plans with fixed jaw and dynamic jaw, and to study lung protection by the plan with split field and fixed jaw. Methods Treatment plans were collected from 12 patients with peripheral lung cancer and mediastinal lymph node metastasis who were treated with IMRT in our hospital. All plans used the dynamic jaw technique. The plans with split field and fixed jaw were designed based on the identical computed tomography images and planning target volume (PTV). Each jaw position in split field depended on each separate PTV. The prescription dose was 60 Gy in 30 fractions. 95% PTV was planned to receive 100% of the prescription dose. Dosimetric parameters of PTV, conformity index (CI), heterogeneity index (HI), number of monitor units (MUs), and dose-volume values of the lung and heart were obtained from dose-volume histogram. Comparison between the two plans was made by paired t test. Results Both plans met clinical requirements. There were no significant differences in D₂, D₉₈, CI, or HI of PTV between the two plans (all P>0.05). Compared with the dynamic jaw plan, the fixed jaw plan had MUs increased by 15%-20%(P=0.010). The V₅, V₁₀, V₂₀, V₃₀, and mean dose for the whole lungs were significantly lower in the fixed jaw plan than in the dynamic jaw plan (P=0.000,0.000,0.000,0.002,0.000). The V₅, V₂₀, and mean dose for the healthy lung were also significantly lower in the fixed jaw plan than in the dynamic jaw plan (P=0.000,0.017,0.000). There were no significant differences in dose-volume values for the spinal cord or heart between the two plans (all P>0.05). Conclusions IMRT with split field and fixed jaw is recommended for patients with peripheral lung cancer and mediastinal lymph node metastasis. The therapy to a certain extent reduces low-dose volume for the lung and the incidence of radiation-induced pneumonitis.

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	Wang Hao
	Chen Hua
	Gu Hengle
	Cai Xuwei
	Guo Jindong
	Wang Changlu
	Xu Zhiyong

Key words： Lymph node metastasis of longitudinal hiccup,peripheral lung cancer/radiotherapy Intensity-modulated,fixed-jaw method in split fields Intensity-modulated,jaw position auto-chosen method Dosimetry

Received: 31 December 2015

Corresponding Authors: Xu Zhiyong,Email:Email:xzyong12@vip.sina.com

Cite this article:

Wang Hao,Chen Hua,Gu Hengle et al. A study of lung protection in intensity-modulated radiotherapy with split field and fixed jaw techniques for peripheral lung cancer with mediastinal lymph node metastasis[J]. Chinese Journal of Radiation Oncology, 2017, 26(3): 320-323.

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http://journal12.magtechjournal.com/Jweb_fszlx/EN/10.3760/cma.j.issn.1004-4221.2017.03.015 OR http://journal12.magtechjournal.com/Jweb_fszlx/EN/Y2017/V26/I3/320

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