Assessing HyperSight iterative CBCT for dose calculation in online adaptive radiotherapy for pelvis and breast patients compared to synthetic CT

IF 2 4区医学 Q3 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Journal of Applied Clinical Medical Physics Pub Date : 2025-03-03 DOI:10.1002/acm2.70038

Jingwei Duan, Joel A. Pogue, Dennis N. Stanley, Sui Shen, Natalie N. Viscariello, Carlos E. Cardenas, Richard A. Popple, Joseph Harms

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引用次数: 0

Abstract

Purpose/objectives

Recent technological advancements have increased efficiency for clinical deliverability of online-adaptive-radiotherapy (oART). Previous cone-beam-computed-tomography (CBCT) generations lacked the ability to provide reliable Hounsfield-units (HU), thus requiring oART workflows to rely on synthetic-CT (sCT) images derived through deformable-image-registration (DIR) between the planning CT (pCT) and the daily CBCT. These sCTs are prone to errors stemming from DIR, potentially contributing to dosimetric errors. This study aims to evaluate the capability of direct dose calculation using a novel CBCT platform, HyperSight (Varian-Medical-Systems), as an alternative for sCT.

Methods/materials

To validate the HyperSight iterative CBCT (HS-iCBCT) HU accuracy, 125 kV and 140 kV HS-iCBCT calibration curves were benchmarked against a pCT calibration curve. To determine the clinical impact of HS-iCBCT compared to sCT, daily adaptive sessions from 47 oART fractions from 10 patients were analyzed. For these patients, HS-iCBCT was acquired for daily adaption, and sCT was generated as part of the standard adaptive workflow. After daily adaption, dose was recalculated directly using the HS-iCBCT, and the HS-iCBCT and sCT dose distributions were compared by γ-index and dose-volume-histogram (DVH) analysis.

Results

The mean HU differences of pCT minus HS-iCBCT (140/125 kV) were −40.97/−57.79, 9.86/21.74, and 87.22/158.20 for lung, water, and bone. In the patient cohort, the median gamma passing rates between HS-iCBCT and sCT-based dose calculations for 3%/2 mm and 1%/1 mm were 99.57 and 96.45% with 10% threshold, and 99.92% and 86.15% with 80% threshold. Dosimetric deviations in high dose regions were concentrated in areas with larger deformation, that is, surface change and variable bladder/bowel filling. The median (min-max) D98%/V100% absolute deviations were 0.3(0.0–1.6)/0.0(0.0–13.7) and 0.4(0.0–1.4)/0.5(0.0–17.5) for CTVs and PTVs.

Conclusions

The HS-iCBCT platform with iterative reconstruction provides dose calculation comparable to sCT for pelvis and breast patients. However, acceptable, yet noticeable, dose discrepancies between HS-iCBCT and sCT exist, particularly in high-dose regions. Further investigations are needed to benchmark these methods against ground truth measurements.

Abstract Image

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评估HyperSight迭代CBCT与合成CT在骨盆和乳房患者在线适应性放疗中的剂量计算。

目的/目标：最近的技术进步提高了在线适应性放射治疗（oART）的临床递送效率。前几代锥形束计算机断层扫描（CBCT）缺乏提供可靠的霍斯菲尔德单元（HU）的能力，因此要求oART工作流程依赖于通过计划CT （pCT）和日常CBCT之间的变形图像配准（DIR）获得的合成CT （sCT）图像。这些sct容易出现由DIR引起的错误，可能导致剂量学错误。本研究旨在评估使用新型CBCT平台HyperSight （Varian-Medical-Systems）作为sCT替代方案的直接剂量计算能力。方法/材料：为验证HyperSight迭代CBCT (HS-iCBCT) HU精度，分别对125 kV和140 kV HS-iCBCT校准曲线与pCT校准曲线进行基准比对。为了确定HS-iCBCT与sCT相比的临床影响，分析了来自10名患者的47个oART分数的每日适应性会话。对于这些患者，获得HS-iCBCT进行日常适应，并生成sCT作为标准适应工作流程的一部分。每日适应后，直接使用HS-iCBCT重新计算剂量，并通过γ-指数和剂量-体积-直方图（DVH）分析比较HS-iCBCT和sCT的剂量分布。结果：pCT + HS-iCBCT （140/125 kV）肺、水、骨的平均HU差值分别为-40.97/-57.79、9.86/21.74、87.22/158.20。在患者队列中，HS-iCBCT和基于sct的剂量计算在3%/2 mm和1%/1 mm时的中位伽马通过率分别为99.57和96.45%（阈值为10%）和99.92%和86.15%（阈值为80%）。高剂量区剂量学偏差集中在变形较大的区域，即表面变化和膀胱/肠道充盈变化。ctv和pttv的D98%/V100%绝对偏差中位数（min-max）分别为0.3(0.0-1.6)/0.0（0.0-13.7）和0.4(0.0-1.4)/0.5（0.0-17.5）。结论：具有迭代重建的HS-iCBCT平台为骨盆和乳房患者提供了与sCT相当的剂量计算。然而，HS-iCBCT和sCT之间存在剂量差异，特别是在高剂量区域，这是可以接受的，但也是值得注意的。需要进一步的调查，将这些方法与地面真值测量相比较。

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

Journal of Applied Clinical Medical Physics 医学-核医学

CiteScore

3.60

自引率

19.00%

发文量

331

审稿时长

3 months

期刊介绍： Journal of Applied Clinical Medical Physics is an international Open Access publication dedicated to clinical medical physics. JACMP welcomes original contributions dealing with all aspects of medical physics from scientists working in the clinical medical physics around the world. JACMP accepts only online submission. JACMP will publish: -Original Contributions: Peer-reviewed, investigations that represent new and significant contributions to the field. Recommended word count: up to 7500. -Review Articles: Reviews of major areas or sub-areas in the field of clinical medical physics. These articles may be of any length and are peer reviewed. -Technical Notes: These should be no longer than 3000 words, including key references. -Letters to the Editor: Comments on papers published in JACMP or on any other matters of interest to clinical medical physics. These should not be more than 1250 (including the literature) and their publication is only based on the decision of the editor, who occasionally asks experts on the merit of the contents. -Book Reviews: The editorial office solicits Book Reviews. -Announcements of Forthcoming Meetings: The Editor may provide notice of forthcoming meetings, course offerings, and other events relevant to clinical medical physics. -Parallel Opposed Editorial: We welcome topics relevant to clinical practice and medical physics profession. The contents can be controversial debate or opposed aspects of an issue. One author argues for the position and the other against. Each side of the debate contains an opening statement up to 800 words, followed by a rebuttal up to 500 words. Readers interested in participating in this series should contact the moderator with a proposed title and a short description of the topic