Dosimetric evaluation and gradient analysis of various MLC leaf-width effects in external beam radiation therapy: TrueBeam Vs Halcyon

IF 2.5 Q2 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Radiography Pub Date : 2024-10-01 DOI:10.1016/j.radi.2024.10.007

R. Shende , S.J. Dhoble , D. Saroj , G. Gupta

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引用次数: 0

Abstract

Introduction

This study investigates dosimetric influence and gradient-analysis of leaf-width of various Multi-leaf-collimators (MLC) from Truebeam and Halcyon linear accelerators.

Methods

The leaf-width effects of Millennium120 and HD120MLC from Truebeam and SX1 and SX2 from Halcyon were studied using virtual phantom in Eclipse16.1.2 TPS. Target structures consist of bore and wave cylinders of equally spaced projected Planning target volume (PTV) of diameters ranging from 1-to-5 cm and 20 cm length. Treatment plans for all PTVs, and four different MLCs configurations from both machines were created utilizing 6MVFFF beam to deliver dose of 50Gy/25# using IMRT and VMAT. Plans were evaluated using plan quality indices including dose conformity, homogeneity, gradient radius, and Monitor-unit (MU). Also, dose gradients were analyzed by estimating distinct integral volume V_D% and paired-t-tests were performed to evaluate statistical differences.

Results

All the plan satisfied the minimum criteria of D_95 %≥prescription dose and V_{107 %}≤2cc. Mean conformity and homogeneity indices for SX1MLC(CI = 0.680,HI = 0.022) were found significantly higher and lower than SX2(CI = 0.746,HI = 0.016), Millennium120 (CI = 0.739,HI = 0.012), and HD120MLC(CI = 0.745,HI = 0.017), respectively. However, CI and HI for SX2, Millennium120, and HD120MLC found comparable. Gradient radius enclosing 50 % of isodose observed maximum and minimum for SX1 and HD120MLC, respectively. Plan MUs for Truebeam MLCs were found approximately 25 % higher than Halcyon MLCs. Dose distribution generated using SX2 and Millennium120 found comparable, however p ≤ 0.05 ascertained substantial differences among SX1, Millennium120, and HD120MLC.

Conclusion

MLC leaf-width influences intensity-modulation and significantly alters dosimetric outcome depending on the magnitude of the leaf-width. HD120MLC does not show much significant advantages over SX2 and Millennium120 except gradient control.

Implications for practice

Halcyon SX1MLC produces least effective plan compared to all other MLC types. However, SX2 and Millennium120 can produce plans of comparable quality except plan MUs difference.

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外照射放射治疗中各种 MLC 叶宽效应的剂量学评估和梯度分析：TrueBeam 与 Halcyon。

简介：本研究调查了Truebeam和Halcyon直线加速器的各种多叶集束器（MLC）叶宽的剂量学影响和梯度分析：使用 Eclipse16.1.2 TPS 中的虚拟模型研究了 Truebeam 公司的 Millennium120 和 HD120MLC 以及 Halcyon 公司的 SX1 和 SX2 的叶宽影响。靶结构由直径为 1-5 厘米、长度为 20 厘米的等间距投射规划靶体积（PTV）的孔和波圆柱组成。使用 IMRT 和 VMAT，利用 6MVFFF 射束为所有 PTV 和两台设备的四种不同 MLC 配置创建治疗计划，提供 50Gy/25# 的剂量。使用包括剂量一致性、均匀性、梯度半径和监测器单位（MU）在内的计划质量指标对计划进行评估。此外，还通过估算不同的积分体积 VD%来分析剂量梯度，并进行配对 t-t 检验来评估统计差异：结果：所有计划都符合 D95 %≥ 处方剂量和 V107 %≤2cc 的最低标准。SX1MLC(CI = 0.680,HI = 0.022)的平均符合性指数和均一性指数分别显著高于和低于 SX2(CI = 0.746,HI = 0.016)、Millennium120(CI = 0.739,HI = 0.012)和 HD120MLC(CI = 0.745,HI = 0.017)。不过，SX2、Millennium120 和 HD120MLC 的 CI 和 HI 值相当。在 SX1 和 HD120MLC 中，包围 50 % 等剂量的梯度半径分别为最大值和最小值。Truebeam MLC 的计划 MU 比 Halcyon MLC 高约 25%。使用 SX2 和 Millennium120 生成的剂量分布具有可比性，但 p ≤ 0.05 表明 SX1、Millennium120 和 HD120MLC 之间存在显著差异：结论：MLC叶宽会影响强度调制，并根据叶宽的大小显著改变剂量测定结果。除梯度控制外，HD120MLC 与 SX2 和 Millennium120 相比并无明显优势：实践意义：与所有其他类型的 MLC 相比，Halcyon SX1MLC 所产生的计划效果最差。实践启示：与所有其他 MLC 相比，Halcyon SX1MLC 生成的平面图效果最差，但 SX2 和 Millennium120 除平面图 MUs 不同外，可生成质量相当的平面图。

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

Radiography RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING-

CiteScore

4.70

自引率

34.60%

发文量

169

审稿时长

63 days

期刊介绍： Radiography is an International, English language, peer-reviewed journal of diagnostic imaging and radiation therapy. Radiography is the official professional journal of the College of Radiographers and is published quarterly. Radiography aims to publish the highest quality material, both clinical and scientific, on all aspects of diagnostic imaging and radiation therapy and oncology.