A method to convert biologically equivalent DVH for different fractionations in radiotherapy with a build-in script

IF 1.7 4区医学 Q4 ONCOLOGY

Medical Dosimetry Pub Date : 2026-01-01 Epub Date: 2026-01-27 DOI:10.1016/j.meddos.2025.12.003

Siyao Zhong MSc , Jiahao Su MSc , Han Guo MSc , Bin Sun BSc , Xuan Liu PhD , Cheng Xu MSc , Xianxiu Nan MSc , Yuyan Gao PhD , Jian-Yue Jin PhD

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引用次数: 0

Abstract

Background

Advancements in radiotherapy have led to diverse fractionation schemes for cancer treatment. Dosimetric assessment for moderately hypo-fractionated radiotherapy (mHFRT) plans is usually challenging due to the absence of explicit dose thresholds for these fractionations and the limitations of standard equivalent dose in 2 Gy per fraction (EQD2) conversion approach in dose volume histogram (DVH) conversion.

Purpose

This study aims to develop a method for converting physical DVHs of mHFRT into equivalent DVHs for conventional-fractionated radiotherapy (CFRT).

Methods and materials

This study presents an improved method, named EQDd (equivalent dose in d Gy fractions), for converting physical DVHs of mHFRT to equivalent DVHs of CFRT. Unlike the traditional EQD2 conversion method that uses a constant dose of 2 Gy per fraction, the EQDd method converts each mHFRT dose point with variable per-fraction doses. The conversion formula is expressed as

E Q D d_{i} = D_{i} * (1 + d_{i} / (α / β)) / (1 + 2 * d_{i} / (d_{P} * α / β)) (i = 1, 2, \dots m)

, where d_p is the prescription dose per fraction. Validation and illustration were performed by comparing the EQDd and EQD2 conversions for DVHs of an exemplary thoracic plan with 3 hypothetical prescriptions: (1) 2 Gy x 30; (2) 3 Gy x 20; (3) 4 Gy x 15, respectively. Additionally, a plugin for the Eclipse treatment planning system based on Eclipse Scripting Application Programming Interface (ESAPI) was developed to automate these conversions.

Results

For the 2 Gy x 30 prescription, the DVHs after EQDd conversion keep the same as the original DVHs, while EQD2 underestimates the volumetric doses of organs at risk (OARs). For the mHFRT plans (3 Gy x 20 and 4 Gy x 15), the DVHs after EQDd conversion show higher dose/volume than the original DVH for all structures, reflecting the increased biological effect for larger fraction sizes. While EQD2 appears to be only suitable for evaluating hotspots in the target and nearby serial organs, its utility for assessing full DVH patterns is limited. A plugin ``DVH Convert'' based on ESAPI has also been developed, which can convert DVH of an mHFRT to CFRT by EQDd method within just a few seconds.

Conclusions

This study demonstrated the limitations of the EQD2 conversion method for OARs. The improved EQDd method provides more biologically reasonable conversions, which may have important applications for clinical dose evaluation.

查看原文本刊更多论文

一种用内置脚本转换放射治疗中不同分数的生物等效DVH的方法

放射治疗的进步导致了癌症治疗的不同分级方案。中等次分割放疗（mHFRT）计划的剂量学评估通常具有挑战性，因为这些分割缺乏明确的剂量阈值，并且剂量-体积直方图（DVH）转换中2 Gy / fraction （EQD2）转换方法的标准等效剂量存在局限性。目的研究一种将mHFRT物理dvh转化为常规分步放疗（CFRT）等效dvh的方法。方法和材料本研究提出了一种改进的方法，称为EQDd（等效剂量d Gy分数），用于将mHFRT的物理dvh转换为CFRT的等效dvh。与传统的EQD2转换方法（每组分使用2 Gy的恒定剂量）不同，EQDd方法将每个mHFRT剂量点转换为可变的每组分剂量。换算公式为EQDdi=Di*(1+ Di /(α/β))/(1+2* Di /(dP*α/β))(i=1,2，…m)，其中dP为每组分的处方剂量。通过比较典型胸椎平面与3种假设处方的dvh的EQDd和EQD2转换来进行验证和说明：(1)2 Gy x 30；(2) 3 Gy × 20；(3) 4 Gy x 15。此外，还为基于Eclipse脚本应用程序编程接口（ESAPI）的Eclipse治疗计划系统开发了一个插件，以实现这些转换的自动化。结果对于2 Gy x 30处方，EQDd转换后的dvh与原dvh保持一致，而EQD2低估了危及器官（OARs）的体积剂量。对于mHFRT方案（3 Gy x 20和4 Gy x 15）， EQDd转换后的DVH在所有结构中都显示出比原始DVH更高的剂量/体积，反映了更大分数尺寸的生物效应增加。虽然EQD2似乎只适用于评估靶点和附近系列器官的热点，但其用于评估全DVH模式的效用有限。本文还开发了一个基于ESAPI的“DVH转换”插件，该插件可以在几秒钟内通过EQDd方法将mHFRT的DVH转换为CFRT。结论本研究证明了EQD2转换方法用于OARs的局限性。改进的EQDd方法提供了更合理的生物学转换，可能在临床剂量评估中具有重要应用价值。

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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来源期刊

Medical Dosimetry 医学-核医学

CiteScore

2.40

自引率

0.00%

发文量

审稿时长

34 days

期刊介绍： Medical Dosimetry, the official journal of the American Association of Medical Dosimetrists, is the key source of information on new developments for the medical dosimetrist. Practical and comprehensive in coverage, the journal features original contributions and review articles by medical dosimetrists, oncologists, physicists, and radiation therapy technologists on clinical applications and techniques of external beam, interstitial, intracavitary and intraluminal irradiation in cancer management. Articles dealing primarily with physics will be reviewed by a specially appointed team of experts in the field.