Monte Carlo simulation of lateral electron disequilibrium in different lung density phantoms after small-field radiation(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2019年第4期
- Page:
- 379-383
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Monte Carlo simulation of lateral electron disequilibrium in different lung density phantoms after small-field radiation
- Author(s):
- LI Jie1; 2; WANG Hui1; WANG Dong1; ZHENG Huaqing1; WU Yican1
- 1. Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei 230031, China; 2. Science Island Branch, University of Science and Technology of China, Hefei 230026, China
- Keywords:
- ; Keywords: small field; lung density; radiotherapy; electron disequilibrium; Monte Carlo simulation
- PACS:
- R811.1；R312
- DOI:
- DOI:10.3969/j.issn.1005-202X.2019.04.002
- Abstract:
- Abstract: Objective To study the effects of small-field radiation on lateral electron disequilibrium in different lung density phantoms and provide references for small-field radiotherapy for lung cancers. Methods Monte Carlo code EGSnrc/DOSXYZnrc was used to simulate different densities of lung tissues after radiation with different field sizes. The combinations of 2 kinds of energies (6 MV and 15 MV), 8 kinds of field sizes (from 0.2 cm×0.2 cm to 3.0 cm×3.0 cm) and 7 kinds of lung densities (from 0.001 g/cm3 to 1.000 g/cm3) were selected in the simulation. The lateral electron disequilibrium was evaluated by dose reduction percentage. Results The dose reduction percentage was very large and changed remarkably with the density when the lung density was less than 0.4 g/cm3. However, when the lung density was greater than 0.4 g/cm3, the change of dose reduction percentage was mitigated with the density. The attenuation of lung dose decreased with the increase of radiation field, and the doses in the small fields behind the lung tissues were significantly increased. Conclusion In a range of low density, the change of density might cause dramatic changes in the lung dose. During the treatment for lung cancer, medical physicists should pay more attention to the accuracy of the CT- electron density conversion curves and select the optimal radiotherapy parameters to protect the organs-at-risk around the lungs. A more accurate dose calculation method considering the electron disequilibrium is recommended in the low-density lung dose calculation.
Last Update: 2019-04-22