Differences between anisotropic analytical algorithm and portal dose image prediction algorithm in dose prediction in volumetric modulated arc therapy using flattening filter free beams(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2020年第4期
- Page:
- 419-425
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Differences between anisotropic analytical algorithm and portal dose image prediction algorithm in dose prediction in volumetric modulated arc therapy using flattening filter free beams
- Author(s):
- YAO Kaining; WANG Ruoxi; YUE Haizhen; WANG Meijiao; PU Yichen; WU Hao
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Radiotherapy, Peking University Cancer Hospital & Institute, Beijing 100142, China
- Keywords:
- Keywords: volumetric modulated arc therapy; flattening filter free; portal dose image prediction algorithm; anisotropic analytical algorithm; electronic portal imaging device; complexity metric
- PACS:
- R811.1；R815
- DOI:
- DOI:10.3969/j.issn.1005-202X.2020.04.005
- Abstract:
- Abstract: Objective To explore the difference between anisotropic analytical algorithm (AAA) and portal dose image prediction (PDIP) algorithm in γ analysis for the pre-treatment verification of volumetric modulated arc therapy using flattening filter free (FFF) beams and to investigate the effects of plan complexity on the difference for providing a basis for the selection of dose prediction algorithm based on electronic portal imaging device (EPID). Methods Two test fields and 16 head and neck treatment plans using 6 MV FFF were selected. AAA and PDIP algorithm were used to generate predicted data, and a γ analysis between predicted data and the data measured by EPID was conducted. The Delta γ of the two algorithms under different γ criteria were analyzed. The complexity metric (CM) of each field in the above cases was calculated, and the correlation between Delta γ and CM under different γ criteria was investigated. Finally, the γ distribution was described by γmean, γsd, γ1 and γ passing rates, and their correlations with CM were discussed. Results For the test field under the criterion of 3%/3 mm or 2%/2 mm, the Delta γ of two algorithms was small. When the criterion was 1%/1 mm, there was significant difference in Delta γ for different open fields. The passing rate of PDIP algorithm was lower than that of AAA when the field was smaller than (10×10) cm2; and the passing rates of two algorithms was basically the same when the field was (10×10) cm2; with the further enlargement of field, the passing rate of PDIP algorithm was significantly higher than that of AAA. The relationship between the passing rates of all fields and evaluation criteria was similar. Under the criterion of 3%/ 3 mm, there was trivial difference in the passing rate of two algorithms. As the criterion increases, the passing rates of two algorithms were gradually decreased and the difference between them become obvious. The CM was positively correlated with Delta γ, γmean, γsd, γ1, and negatively related with γ passing rate. Conclusion PDIP algorithm has a higher accuracy for dose prediction based on EPID with arm support, while AAA is suitable for dose prediction based on EPID without arm support or field with less backscattering effect. When plan complexity or evaluation criterion increases, the difference between two algorithms increases. The plan complexity has a negative effect on FFF plan verification. An appropriate plan verification tool should be adopted to ensure the safe and effective treatment in clinic.
Last Update: 2020-04-29