Deufel Christopher L, Brost Eric E, Dupere Justine M, Wilson Jessica M, Waddle Mark R, Stish Bradley J
Department of Radiation Oncology, Mayo Clinic, Rochester, MN 55905.
Department of Radiation Oncology, Mayo Clinic, Rochester, MN 55905.
Brachytherapy. 2025 May-Jun;24(3):450-460. doi: 10.1016/j.brachy.2025.01.003. Epub 2025 Feb 17.
To develop and deploy an electromagnetic (EM) tracking-based platform for pretreatment, patient-specific quality assurance of brachytherapy applicator digitization, with the goals of intercepting human errors and quantifying treatment planning dose uncertainties.
An EM tracking platform, EMQA, was developed for patient-specific quality assurance of HDR treatment plan needle reconstructions. EMQA compared needle geometry between a manually digitized clinical HDR treatment plan and EM-tracked positions. Pretreatment quality assurance (QA) was performed for 25 implants (20 patients). Distance and dose metric differences were reported. Factors influencing accuracy were analyzed, including radial distance from the ultrasound probe and EM field generator (EFG), needle 'shadowing' artifacts, needle depth adjustments using exposed needle length protruding from the implant template, and TRUS calibrated speed of sound, v.
Needle digitization differences between the clinical plan and EM tracking had a magnitude (mean ± standard deviation [minimum, maximum]) of 0.46 ± 0.36 (0.002, 2.19) millimeters for the needle depths and 0.62 ± 0.44 (0.01, 3.26) millimeters for needle shafts. Dose metric differences (% of Rx) for PTV, CTV, bladder, rectum, and urethra were <1.7% on average, but differences >5% were observed in two patients. Accuracy was notably worse for locations shadowed by more than one needle, decreased with distance from the probe and EFG, and was optimal for v=1570 m/s.
Clinical evaluation of an EMQA platform demonstrated the potential to intercept errors in the digital reconstruction of ultrasound-based prostate HDR brachytherapy needles prior to radiation delivery, which may be due to poor image quality or human error. Manual needle digitization accuracy was typically submillimeter, however errors as great as 3 mm were observed. The adoption of EMQA as standard of care is expected to reduce the potential for mistreatment.
开发并部署一个基于电磁（EM）跟踪的平台，用于近距离放射治疗施源器数字化的预处理、患者特异性质量保证，目标是拦截人为错误并量化治疗计划剂量不确定性。
开发了一个EM跟踪平台EMQA，用于HDR治疗计划针重建的患者特异性质量保证。EMQA比较了手动数字化临床HDR治疗计划与EM跟踪位置之间的针几何形状。对25例植入患者（20例患者）进行了预处理质量保证（QA）。报告了距离和剂量指标差异。分析了影响准确性的因素，包括距超声探头和电磁场发生器（EFG）的径向距离、针的“阴影”伪影、使用从植入模板突出的暴露针长度进行的针深度调整以及经TRUS校准的声速v。
临床计划与EM跟踪之间的针数字化差异，针深度的幅度（平均值±标准差[最小值，最大值]）为0.46±0.36（0.002，2.19）毫米，针杆为0.62±0.44（0.01，3.26）毫米。PTV、CTV、膀胱、直肠和尿道的剂量指标差异（处方剂量的百分比）平均<1.7%，但在两名患者中观察到差异>5%。对于被一根以上针遮挡的位置，准确性明显更差，随着与探头和EFG距离的增加而降低，并且在v = 1570 m/s时最佳。
EMQA平台的临床评估表明，在放射治疗前，有可能拦截基于超声的前列腺HDR近距离放射治疗针数字化重建中的错误，这可能是由于图像质量差或人为错误所致。手动针数字化的准确性通常在亚毫米级别，但观察到高达3毫米的误差。采用EMQA作为护理标准有望降低误治疗的可能性。
