Dosimetric benefit to organs at risk following margin reductions in nasopharyngeal carcinoma treated with intensity-modulated radiation therapy

Cancer Communications

Ying Sun¹  Rui Guo¹  Zhen-Yu Qi¹  Wen-Jing Yin²  Jun Ma²  Feng Chi²  Guang-Shun Zhang³  Meng-Zhong Liu⁴  Jian-Lan Fang⁴  Yan-Ping Mao⁴ 

[1] Collaborative Innovation Center for Cancer Medicine, Guangzhou, Peoples Republic of China;State Key Laboratory of Oncology in South China;Department of Radiation Oncology, Cancer Center of Guangzhou Medical University, Guangzhou, Peoples Republic of China;Department of Radiation Oncology, Sun Yat-sen University Cancer Center

关键词: Margin;    Dosimetry;    Organs at risk;    Cone beam computer tomography;    Nasopharyngeal carcinoma;   

DOI  :  10.1186/s40880-015-0016-8

学科分类：肿瘤学

来源: Springer

【 摘 要 】

It is important to decrease the radiation exposure of normal tissue in intensity-modulated radiation therapy (IMRT). Minimizing planning target volume (PTV) margins with more precise target localization techniques can achieve this goal. This study aimed to quantify the extent to which organs at risk (OARs) are spared when using reduced margins in the treatment of nasopharyngeal carcinoma (NPC). Two IMRT plans were regenerated for 40 patients with NPC based on two PTV margins, which were reduced or unchanged following cone beam computed tomography online correction. The reduced-margin plan was optimized based on maximal dose reduction to OARs without compromising target coverage. Dosimetric comparisons were evaluated in terms of target coverage and OAR sparing. Improvements in target coverage occurred with margin reduction, and significant improvements in dosimetric parameters were observed for all OARs (P < 0.05) except for the right optic nerve, chiasm, and lens. Doses to OARs decreased at a rate of 1.5% to 7.7%. Sparing of the left parotid and right parotid, where the mean dose (Dmean) decreased at a rate of 7.1% and 7.7%, respectively, was greater than the sparing of other OARs. Significant improvements in OAR sparing were observed with margin reduction, in addition to improvement in target coverage. The parotids benefited most from the online imaging-guided approach.

【 授权许可】

CC BY