Three-dimensional dose uncertainty maps based on the fraction of field edge dose for volumetric modulated arc therapy plans

IF 3.4 Q2 ONCOLOGY

Physics and Imaging in Radiation Oncology Pub Date : 2025-07-01 DOI:10.1016/j.phro.2025.100802

Emmanouil Terzidis , Fredrik Nordström , Magnus Gustafsson , Anna Karlsson , Julia Götstedt , Anna Bäck

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Abstract

Background and purpose

Absorbed dose uncertainties in radiotherapy plans are generally larger near field edges compared to the center of the field. The aim of this study was to investigate dose uncertainties related to the field edge in 3D for plans of varying complexities.

Materials and methods

A method was developed for calculation of the fraction of field edge dose (FED), that could be visualized as a 3D uncertainty map (3DUM_FED). Twelve clinical treatment plans were included for four different treatment sites that were reoptimized to create one plan with reduced complexity and one of increased complexity. 3DUM_FED was calculated for all 36 plans. The highest FED for a 2 cm³ volume (FED_{2 cm}³) and average FED (FED_mean) were calculated for the planning target volumes (PTV) and organs at risk (OAR) and compared with the edge area metric (EAM).

Results

High FED (above 20 %) were mainly found just outside the PTV border. FED_mean in PTV was highest for the plans of increased complexity. The FED_mean for PTVs and OARs, as well as the FED_{2 cm}³ for PTVs, correlated with ρ ≥ 0.81 to EAM. The FED_{2 cm}³ for OARs had a weaker correlation with EAM (ρ = 0.55). 3DUM_FED analysis revealed that plan complexity affects different parts of the patient volume in different ways.

Conclusions

3DUM_FED offers a way to estimate dose uncertainties related to the field edge in 3D. It also allows for separate evaluation in different regions of interest, unlike EAM, which mainly correlates with the dose uncertainty related to the PTV.

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基于体积调制电弧治疗方案的场边缘剂量分数的三维剂量不确定度图

背景和目的放射治疗计划中的吸收剂量不确定性通常在近场边缘比在场中心更大。本研究的目的是调查剂量不确定性相关的领域边缘在三维不同复杂性的计划。材料与方法建立了一种计算场边缘剂量（FED）的方法，该方法可以可视化为三维不确定图（3DUMFED）。包括四个不同治疗地点的12个临床治疗计划，这些计划被重新优化以创建一个降低复杂性的计划和一个增加复杂性的计划。计算了所有36个方案的3DUMFED。计算规划目标体积（PTV）和危险器官（OAR）的最高FED （FED2 cm3）和平均FED (FEDmean)，并与边缘面积度量（EAM）进行比较。结果高检出率（20%以上）主要集中在PTV边界外。对于复杂性增加的计划，PTV中的FEDmean最高。ptv和OARs的FEDmean以及ptv的FED2 cm3与EAM的相关性为ρ≥0.81。桨的FED2 cm3与EAM的相关性较弱（ρ = 0.55）。3DUMFED分析显示，平面图复杂性以不同的方式影响患者体积的不同部位。结论dumfed提供了一种估算三维场边缘剂量不确定度的方法。它还允许在不同感兴趣的区域进行单独评估，这与EAM不同，EAM主要与与PTV相关的剂量不确定度相关。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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