Dose Calculation Accuracy of Individualized Bulk Electron Density Assignment Approaches for Simulated MRI-only Planning of Thoracic Tumors

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Abstract Objective This study aimed to investigate the dose calculation accuracy of individualized bulk electron density (IBED) assignment approaches for simulated magnetic resonance imaging (MRI)-only planning of thoracic tumors via the use of a 3DVH system. Methods 8 patients with thoracic cancer were included in this study. Based on standard planning CT,single-arc dynamic conformal therapy (DCT) and double-arc volumetric modulated arc therapy (VMAT) plans with a 6 MV photon beam were generated as a baseline plan (Plan-CT) for each patient. The simulated MRI-only planning (Plan-IBED) was implemented by copying the Plan-CT and forcing the electron density of each region of interest to its average value and recalculating the dose distribution. A 3DVH system was used to visualize and compare the dosimetric differences between Plan-CT and Plan-IBED,and the criteria of the 3D-Gamma pass rate were set to 1.0%/1.0 mm. Results The maximum percentage relative deviation (MPRD) of the dosimetric parameters D₂,D₉₅,D₉₈,and D_mean of planning tumor volumes (PTVs) between Plan-CT and Plan-IBED was less than 1.3%. The MPRD of the average dose for organs at risk (OARs) was less than 1.5%. The MPRDs of the lung V₅,V₂₀,and V₃₀ were 1.29%,3.26%,and 2.78%,respectively. Gamma analysis revealed an averaged pass rate of >95.0% for the body,as well as between 91.9% and 98.2% for OARs. Conclusion The proposed IBED assignment in simulated MRI-only treatment planning allows for dose calculation with comparable accuracy to the baseline plan and is appropriate for thoracic tumors.

Key words： Individualized bulk electron density (IBED) Relative electron density (RED) Thoracic cancer 3DVH software MRI-only planning

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	Articles by authors
	Shuxu Zhang
	Qingxing Zeng
	Yuliang Liao
	Shengqu Lin
	Guoquan Zhang
	Huaiyu Lei
	Ruihao Wang
	Hui Yu
	Quanbin Zhang
	Ping Li

Cite this article:

Shuxu Zhang,Qingxing Zeng,Yuliang Liao, et al. Dose Calculation Accuracy of Individualized Bulk Electron Density Assignment Approaches for Simulated MRI-only Planning of Thoracic Tumors[J]. Chinese Journal of Biomedical Engineering, 2020, 29(3): 40-46.

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http://manu32.magtech.com.cn/Jwk_zgswyx_en/EN/ OR http://manu32.magtech.com.cn/Jwk_zgswyx_en/EN/Y2020/V29/I3/40

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