Radiation Oncology Department, Lahey Clinic, Burlington, MA 01805, USA.
J Appl Clin Med Phys. 2013 Jan 7;14(1):4098. doi: 10.1120/jacmp.v14i1.4098.
The objective of this study was to develop a standardized procedure from simulation to treatment delivery for the multichannel Miami applicator, in order to increase planning consistency and reduce errors. A plan is generated prior to the 1st treatment using the CT images acquired with the applicator in place, and used for all 3 fractions. To confirm the application placement before each treatment fraction, an AP image is acquired and compared with the AP baseline image taken at simulation. A preplanning table is generated using the EBRT doses and is used to compute the maximum allowable D2cc for bladder, rectum, and sigmoid, and the mean allowable dose for the upper vaginal wall per HDR brachytherapy fraction. These data are used to establish the criteria for treatment planning dose optimization. A step-by-step treatment planning approach was developed to ensure appropriate coverage for the tumor (D90 > 100% prescribed dose of 700 cGy/fraction) and the uninvolved vaginal surface (dose for the entire treatment length > 600 cGy/fraction), while keeping the organs at risk below the tolerance doses. The equivalent dose 2 Gy (EQD2) tolerances for the critical structures are based on the American Brachytherapy Society (ABS) recently published guidelines. An independent second check is performed before the 1st treatment using an in-house Excel spreadsheet. This methodology was successfully applied for our first few cases. For these patients: the cumulative tumor dose was 74-79 EQD2 Gy10 (ABS recommended range 70-85); tumor D90 was >100% of prescribed dose (range 101%-105%); cumulative D2cc for bladder, rectum, and sigmoid were lower than the tolerances of 90, 75, and 75 EQD2 Gy3, respectively; cumulative upper vaginal wall mean dose was below the tolerance of 120 EQD2 Gy3; the second check agreement was within 5%. By using a standardized procedure the planning consistency was increased and all dosimetric criteria were met.
本研究旨在为多通道 Miami 施源器制定从模拟到治疗实施的标准化流程，以提高计划的一致性并减少误差。在第一次治疗前，使用带有施源器的 CT 图像生成计划，并在所有 3 个分次中使用。为了在每次治疗分次前确认施源器的位置，获取一个 AP 图像，并与模拟时获取的 AP 基准线图像进行比较。使用 EBRT 剂量生成预规划表，并用于计算膀胱、直肠和乙状结肠的最大允许 D2cc 以及 HDR 近距离治疗每个分次的上阴道壁的平均允许剂量。这些数据用于为治疗计划剂量优化建立标准。开发了一种逐步治疗计划方法，以确保肿瘤（D90 > 100%规定的 700 cGy/分次剂量）和未受累阴道表面（整个治疗长度的剂量 > 600 cGy/分次）得到适当覆盖，同时将危险器官的剂量保持在耐受剂量以下。关键结构的 2 Gy 等效剂量（EQD2）耐受度基于美国近距离治疗协会（ABS）最近发布的指南。在第一次治疗前，使用内部 Excel 电子表格进行独立的第二次检查。这种方法已成功应用于我们的前几个病例。对于这些患者：累积肿瘤剂量为 74-79 EQD2 Gy10（ABS 推荐范围为 70-85）；肿瘤 D90 高于规定剂量的 100%（范围为 101%-105%）；膀胱、直肠和乙状结肠的累积 D2cc 均低于各自 90、75 和 75 EQD2 Gy3 的耐受度；累积上阴道壁平均剂量低于 120 EQD2 Gy3 的耐受度；第二次检查的一致性在 5%以内。通过使用标准化流程，提高了计划的一致性，并满足了所有剂量学标准。
