Evaluation of cumulative dose distributions from external beam radiation therapy using CT-to-CBCT deformable image registration (DIR) for cervical cancer patients.

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

Journal of Applied Clinical Medical Physics Pub Date : 2024-10-04 DOI:10.1002/acm2.14538

Carolyn Eckrich, Brandon Lee, Chunhao Wang, Kim Light, Junzo Chino, Anna Rodrigues, Oana Craciunescu

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引用次数: 0

Abstract

Purpose: To investigate dose differences between the planning CT (pCT) and dose calculated on pre-treatment verification CBCTs using DIR and dose summation for cervical cancer patients.

Methods: Cervical cancer patients treated at our institution with 45 Gy EBRT undergo a pCT and 5 CBCTs, once every five fractions of treatment. A free-form intensity-based DIR in MIM was performed between the pCT and each CBCT using the "Merged CBCT" feature to generate an extended FOV-CBCT (mCBCT). DIR-generated bladder and rectum contours were adjusted by a physician, and dice similarity coefficients (DSC) were calculated. After deformation, the investigated doses were (1) recalculated in Eclipse using original plan parameters (ecD), and (2) deformed from planning dose (pD) using the deformation matrix in MIM (mdD). Dose summation was performed to the first week's mCBCT. Dose distributions were compared for the bladder, rectum, and PTV in terms of percent dose difference, dose volume histograms (DVHs), and gamma analysis between the calculated doses.

Results: For the 20 patients, the mean DSC was 0.68 ± 0.17 for bladder and 0.79 ± 0.09 for rectum. Most patients were within 5% of pD for D2cc (19/20), Dmax (17/20), and Dmean (16/20). All patients demonstrated a percent difference > 5% for bladder V45 due to variations in bladder volume from the pCT. D90 showed fewer differences with 19/20 patients within 2% of pD. Gamma rates between pD and ecD averaged 94% for bladder and 94% for rectum, while pD and mdD exhibited slightly better performance for bladder (93%) and lower for rectum (85%).

Conclusion: Using DIR with weekly CBCT images, the MIM deformed dose (mdD) was found to be in close agreement with the Eclipse calculated dose (ecD). The proposed workflow should be used on a case-by-case basis when the weekly CBCT shows marked difference in organs-at-risk from the planning CT.

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利用CT-to-CBCT可变形图像配准（DIR）评估宫颈癌患者体外放射治疗的累积剂量分布。

目的：研究宫颈癌患者的计划 CT（pCT）与使用 DIR 和剂量求和法计算的治疗前验证 CBCT 剂量之间的剂量差异：方法：在我院接受 45 Gy EBRT 治疗的宫颈癌患者每五个疗程接受一次计划 CT 和 5 次 CBCT 检查。使用 "合并 CBCT "功能在 pCT 和每个 CBCT 之间进行基于 MIM 的自由形式强度 DIR，以生成扩展 FOV-CBCT (mCBCT)。由医生调整 DIR 生成的膀胱和直肠轮廓，并计算骰子相似系数 (DSC)。变形后，研究剂量（1）在 Eclipse 中使用原始计划参数重新计算（ecD），（2）使用 MIM 中的变形矩阵从计划剂量（pD）变形（mdD）。对第一周的 mCBCT 进行剂量汇总。通过剂量差百分比、剂量体积直方图（DVH）和计算剂量之间的伽玛分析，比较了膀胱、直肠和 PTV 的剂量分布：20名患者的膀胱和直肠平均DSC分别为0.68 ± 0.17和0.79 ± 0.09。大多数患者的 D2cc（19/20）、Dmax（17/20）和 Dmean（16/20）均在 pD 的 5%以内。由于膀胱容量与 pCT 存在差异，所有患者的膀胱 V45 百分比差异均大于 5%。D90 的差异较小，19/20 患者的差异在 pD 的 2% 以内。pD 和 ecD 之间的伽马率平均为：膀胱 94%，直肠 94%，而 pD 和 mdD 在膀胱方面的表现稍好（93%），在直肠方面较低（85%）：结论：使用每周 CBCT 图像的 DIR，发现 MIM 变形剂量 (mdD) 与 Eclipse 计算剂量 (ecD) 非常接近。当每周 CBCT 显示危险器官与计划 CT 有明显差异时，应根据具体情况使用建议的工作流程。

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