Sauer Birte Christina, Dürrbeck Christopher, Bert Christoph
Department of Radiation Oncology, Uniklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
Comprehensive Cancer Center Erlangen-EMN (CCC ER-EMN), Erlangen, Germany.
J Contemp Brachytherapy. 2024 Aug;16(4):297-305. doi: 10.5114/jcb.2024.143610. Epub 2024 Sep 16.
Electromagnetic tracking (EMT) has great potential as a quality assurance tool in interstitial brachytherapy. Since its clinical application in most cases comprises a comparison with brachytherapy plan data, EMT registration and plan data are crucial. Registration uncertainties influence EMT outcomes and further decision-making processes. The impact of registration using four algorithms on the resulting data was investigated.
Registration abilities of four sub-algorithms, which share the same principle of an iterative closest point approach were considered. Sub-algorithms differ regarding underlying mathematical norms, and also include a non-geometric implementation focusing on stochastic optimization. This study focused on the registration of point clouds originating from data obtained during treatment with interstitial brachytherapy in breast cancer patients. Data were acquired from a hybrid device prototype, capable of EMT measurements and data extracted from treatment plan. Main criteria for good registration performance were good geometric agreement, including low Euclidean distances between registered data sets as well as short registration time. In addition, previously published patient data with different than employed in the original publication algorithm were re-analyzed to further investigate the impact of registration method on clinically influential results.
The stochastic algorithm presented much higher registration times, and earliest implementation of geometric approaches occasionally misaligned patient data. The remaining two algorithms performed almost identically resulted in sufficiently accurate registration performance. The re-analysis of previously published data demonstrated minor inconsistencies between former registration method and different algorithm; however, the overall trends with almost identical mean Euclidean distance of 2.22 mm (2.19 mm in the original work) could be reproduced.
The choice of registration algorithm can influence the quality of registration. Therefore, it is advised to regularly examine the registration performance, especially in in-house programs.
电磁跟踪（EMT）作为间质近距离放射治疗中的一种质量保证工具具有巨大潜力。由于其在大多数临床应用中包括与近距离放射治疗计划数据进行比较，EMT配准和计划数据至关重要。配准不确定性会影响EMT结果和进一步的决策过程。研究了使用四种算法进行配准对所得数据的影响。
考虑了四种子算法的配准能力，它们都采用迭代最近点方法的相同原理。子算法在基础数学范数方面有所不同，还包括一种侧重于随机优化的非几何实现。本研究重点关注源自乳腺癌患者间质近距离放射治疗期间获得的数据的点云配准。数据从一个能够进行EMT测量的混合设备原型获取，并从治疗计划中提取。良好配准性能的主要标准是良好的几何一致性，包括配准数据集之间的低欧几里得距离以及较短的配准时间。此外，对以前发表的与原始发表算法不同的患者数据进行重新分析，以进一步研究配准方法对具有临床影响结果的影响。
随机算法的配准时间长得多，几何方法的早期实现偶尔会使患者数据未对准。其余两种算法的表现几乎相同，配准性能足够准确。对以前发表的数据进行重新分析表明，以前的配准方法与不同算法之间存在轻微不一致；然而，可以重现总体趋势，平均欧几里得距离几乎相同，为2.22毫米（原始工作中为2.19毫米）。
配准算法的选择会影响配准质量。因此，建议定期检查配准性能，尤其是在内部程序中。
