Different optimizing strategies based on spot scanning carbon ion therapy for non-small cell lung cancer
10.3760/cma.j.issn.1004-4221.2018.11.009
- VernacularTitle:基于非小细胞肺癌碳离子点扫描治疗的不同优化策略研究
- Author:
Xiaoli LIU
1
;
Shahnazi KAMBIZ
;
Jingfang MAO
;
Wenjian XU
Author Information
1. 201321,上海市质子重离子医院放射物理科 上海质子重离子放射治疗工程技术研究中心
- Keywords:
Lung neoplasms/intensity-modulated carbon-ion therapy;
Single beam optimization;
Spot scanning carbon-ion;
Plan evaluation3mm]
- From:
Chinese Journal of Radiation Oncology
2018;27(11):994-998
- CountryChina
- Language:Chinese
-
Abstract:
Objective To evaluate the dose variation of target coverage and organs at risk ( OARs) among four planning strategies using spot-scanning carbon-ion radiotherapy for non-small cell lung cancer ( NSCLC) . Methods Ten NSCLC patients utilizing gating motion control were selected to receive dose calculation over multiple acquired 4DCT images. Four optimizing strategies consisted of intensity-modulated carbon-ion therapy ( IMCT-NoAS ) , IMCT combined with internal gross tumor volume ( IGTV ) assigned muscle ( IMCT-ASM ) , single beam optimization ( SBO ) ( SBO-NoAS ) and SBO combined with IGTV assigned muscle (SBO-ASM).The initial plan was re-calculated after the 4DCT data were reviewed and then compared with the initial plan in the dosimetry. Results For re-calculation plans with two reviewing CTs,all four strategies yielded similar planning target volume ( PTV ) coverage. Merely IMCT-NoAS strategy presented with relatively significant variations in dose distribution. Dose variation for OARs between initial and re-calculated plans:for all four strategies,V20 of ipsilateral lung was increased by approximately 2. 0 Gy (relative biological effective dose,RBE),V30 of heart was increased by approximately 1. 0 Gy (RBE) for both IGTV assigned muscle strategies,whereas decreased by approximately 0. 2 Gy ( RBE) for both IGTV non-assigned muscle strategies. The maximum dose of spinal cord was changed by 2. 5 Gy ( RBE ) . Conclusions Carbon-ion radiotherapy is sensitive to the anatomic motion within the tumors along the beam path. When the tumor motion along the head-foot (H-F) direction exceeds 8 mm,SBO-ASM strategy provides better dose coverage of target. Strategies with IGTV assignment may result in dose overshoot to a position deeper than the initial planning dose distribution.
