Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen Nürnberg (FAU), Erlangen, Germany. Strahlenklinik, Universitätsklinikum Erlangen, Universitätsstraße 27, 91054 Erlangen, Germany.
Phys Med Biol. 2018 May 2;63(9):095008. doi: 10.1088/1361-6560/aabb5a.
Multi-catheter interstitial brachytherapy (iBT) is a treatment option for breast cancer patients after breast conserving surgery. Typically, only a few additional quality interventions after the first irradiation have been introduced to ensure the planned treatment delivery. Therefore, the purpose of this study is to show the possibilities of an electromagnetic tracking (EMT) system integrated into the afterloader for quality assurance (QA) in high-dose rate (HDR) iBT of patients with breast cancer. The hybrid afterloader system equipped with an electromagnetic sensor was used for all phantom and patient measurements. Phantom measurements were conducted to estimate the quality of different evaluation schemes. After a coherent point drift registration of the EMT traces to the reconstructed catheters based on computed tomograms the dwell positions (DP) were defined. Different fitting and interpolation methods were analyzed for the reconstruction of DPs. All estimated DPs were compared to the DPs defined in treatment planning. Until now, the implant geometry of 20 patients treated with HDR brachytherapy was acquired and explored. Regarding the reconstruction techniques, both fitting and interpolation were able to detect manually introduced shifts and swaps. Nonetheless, interpolation showed superior results (RMSE = 1.27 mm), whereas fitting seemed to be more stable to distortion and motion. The EMT system proved to be beneficial for QA in brachytherapy and furthermore, clinical feasibility was proven.
多导管间质近距离放疗（iBT）是保乳手术后乳腺癌患者的一种治疗选择。通常，在第一次放疗后仅引入了一些额外的质量干预措施，以确保计划的治疗交付。因此，本研究的目的是展示将电磁跟踪（EMT）系统集成到后装器中用于乳腺癌患者高剂量率（HDR）iBT 的质量保证（QA）的可能性。配备电磁传感器的混合后装器系统用于所有体模和患者测量。进行了体模测量，以估计不同评估方案的质量。在基于计算机断层扫描的 EMT 轨迹与重建导管的相干点漂移配准之后，定义了驻留位置（DP）。分析了不同的拟合和插值方法来重建 DP。将所有估计的 DP 与治疗计划中定义的 DP 进行比较。到目前为止，已经采集和探索了 20 名接受 HDR 近距离放疗治疗的患者的植入物几何形状。关于重建技术，拟合和插值都能够检测到手动引入的移位和交换。然而，插值显示出更好的结果（RMSE=1.27mm），而拟合似乎对变形和运动更稳定。EMT 系统被证明对近距离放疗的 QA 有益，并且进一步证明了临床可行性。
