Abstract

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Title:: Effect of rotational mechanical errors on dose distribution of volumetric modulated arc therapy for multiple intracranial metastases

Author(s):: DENG Guanhua1; LIN Zhengmao2; CHEN Lixia3; DAI Peng1; ZHANG Ping1; LUO Longhui1; LUO Rishun1; LAI Mingyao1; SHAN Changguo1; HUANG Qing1; CAI Linbo1; 1. Department of Oncology, Guangdong Sanjiu Brain Hospital, Guangzhou 510510, China; 2. Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China; 3. School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China

Keywords:: Keywords: multiple intracranial metastases; volumetric modulated arc therapy; rotational mechanical error; single isocenter

Abstract:: Abstract: Objective To investigate the effect of rotational mechanical errors of linear accelerator on the dose distribution of single-isocenter volumetric modulated arc therapy (VMAT) for multiple intracranial metastases. Methods A total of 21 patients with multiple intracranial metastases were enrolled in the study. Assuming that patients were treated with non-coplanar VMAT, the treatment couch and collimator angle were shifted by ±0.5°, ±1.0°, ±1.5° and ±2.0°, respectively. Eclipse 13.6 treatment planning system was used to study the effects of the rotational mechanical errors on dose distribution of VMAT for multiple intracranial metastases. With different rotational errors, the conformity index, gradient index and homogeneity index of target areas as well as the maximum dose of organs-at-risk were recorded and analyzed. Results There were significant differences in the conformity index, gradient index (except for couch), and homogeneity index of target areas (P<0.05) when the rotational deviations of treatment couch and collimator angle were greater than 0.5°. No significant difference was found in the maximum dose of organs-at-risk (P>0.05). Conclusion In the planning of VMAT for multiple intracranial metastases, the distance between the isocenter and target areas should be taken into consideration and the reasonable correction threshold for six-dimensional couch rotational errors should be 0.5°.