Maastricht University Medical Centre, Department of Radiation Oncology (MAASTRO Clinic), School for Oncology and Developmental Biology, Maastricht, the Netherlands.
Maastricht University Medical Centre, Department of Radiation Oncology (MAASTRO Clinic), School for Oncology and Developmental Biology, Maastricht, the Netherlands.
Pract Radiat Oncol. 2017 Nov-Dec;7(6):e369-e376. doi: 10.1016/j.prro.2017.04.012. Epub 2017 Apr 19.
After changing from offline setup verification to online setup verification using external skin markers in breast cancer patients, we noticed an increase in localized acute skin toxicity beneath the markers. Also, in vivo 3-dimensional dose measurements showed deviations between the delivered and the planned dose distributions; therefore, we investigated the accuracy of setup verification using surgical clips in the tumor bed, with a focus on target coverage of whole breast and tumor bed.
Orthogonal kilovoltage images were acquired before every fraction in 35 breast cancer patients, deriving an online 3-dimensional setup error by matching on external skin markers. In retrospect, a rematch was performed using surgical clips. For 155 fractions (ie, 5-6 fractions/patient), a cone beam computed tomography (CT) scan was available. Analysis concerned: (1) visibility of the clips, (2) migration of the clips, (3) comparison of setup errors according to both match methods, and (4) comparison of target coverage by recalculating the dose on the online setup-corrected cone beam CT scan with the patient setup according to both match methods. External validation of the surgical clip-based online setup verification was performed in 23 patients by analyzing kilovoltage images of 100 fractions, obtained after treatment.
All types of surgical clips could be visualized. The clip to center-of-mass distance decreased on average by 2 mm (standard deviation, 1) over the course of treatment. Setup differences between match methods were on average <0.5 mm in all directions. The reconstructed dose distributions showed standard deviations of volumes receiving 95% or 107% of prescribed dose and mean dose of the breast and boost planning target volume were similar for the planning CT and the cone beam CTs, for both match procedures. An external validation in 23 patients showed reassuring setup errors <2 mm.
Online setup verification using surgical clips results in comparable setup corrections and target volume coverage as verification using skin markers. By omitting skin markers acute skin toxicity beneath the markers is prevented.
在乳腺癌患者中从离线设置验证更改为使用外部皮肤标记的在线设置验证后，我们注意到标记下方的局部急性皮肤毒性增加。此外，体内三维剂量测量显示，所传递的和计划的剂量分布之间存在偏差；因此，我们研究了使用肿瘤床中的外科夹进行设置验证的准确性，重点是整个乳房和肿瘤床的目标覆盖。
在 35 名乳腺癌患者的每一次分次治疗前采集正交千伏级图像，通过匹配外部皮肤标记来获得在线三维设置误差。回顾性地，使用外科夹进行重新匹配。对于 155 个分次（即每个患者 5-6 个分次），可以获得锥形束 CT（CBCT）扫描。分析内容包括：（1）夹的可见性，（2）夹的迁移，（3）根据两种匹配方法比较设置误差，（4）通过根据两种匹配方法在在线设置校正的 CBCT 扫描上重新计算剂量，比较目标覆盖情况。在 23 名患者中通过分析治疗后获得的 100 个分次的千伏级图像，对外科夹在线设置验证进行了外部验证。
所有类型的外科夹都可以看到。夹到质心的距离在治疗过程中平均减少了 2 毫米（标准差为 1）。两种匹配方法之间的设置差异在所有方向上平均均<0.5 毫米。重建剂量分布显示，接收处方剂量的 95％或 107％的体积和乳房和增强计划靶体积的平均剂量的标准偏差在计划 CT 和 CBCT 上相似，两种匹配程序均如此。在 23 名患者中的外部验证显示，<2 毫米的设置误差令人放心。
使用外科夹进行在线设置验证可获得与使用皮肤标记验证相似的设置校正和目标体积覆盖。通过省略皮肤标记，可以防止标记下方的急性皮肤毒性。
