Boman Eeva, Kapanen Mika, Laaksomaa Marko, Mäenpää Hanna, Hyödynmaa Simo, Kellokumpu-Lehtinen Pirkko-Liisa
Tampere University Hospital.
J Appl Clin Med Phys. 2016 Jul 8;17(4):86-94. doi: 10.1120/jacmp.v17i4.6149.
The aim of this study was to evaluate the impact of actual rotational setup errors on dose distributions in intracranial stereotactic radiotherapy (SRT) with different alternatives for treatment position selection. A total of 38 SRT fractions from 18patients were retrospectively evaluated with rotational setup errors obtained from actual treatments. The planning computed tomography (CT) images were rotated according to online cone-beam CT (CBCT) images and the dose distribution was recalculated to the rotated CT images using three different patient positionings derived from: 1) an automatic 6D match neglecting rotation correction (Auto6D); 2) an automatic 3D match (Auto3D); and 3) a manual 3D match from actual treatment (Treat3D). The mean conformity index (CI) was 0.92 for the original plans and 0.91 for the Auto6D plans. The mean CI decreased significantly (p < 0.01) to 0.78 and 0.80 for the Auto3D and the Treat3D plans, respectively. The mean minimum dose of the planning target volume (PTVmin) was 91.9% of the prescribed dose for the original plans and 92.1% for the Auto6D plans, while for the Auto3D and the Treat3D plans PTVmin decreased significantly (p < 0.01) to 78.9% and 80.2%, respectively. No significant differences were seen between the Auto6D and the original treatment plans in terms of the dose parameters. However, the Auto3D and the Treat3D plans were statistically significantly inferior (p < 0.01) to the Auto6D and the original plans. In addition, a significant negative correlation (p < 0.01, |r| > 0.38) was found in the Auto3D and the Treat3D cases between the rotation error and CI, PTVmin or minimum dose of gross tumour volume. In SRT, a treatment plan of comparable quality to 6D rotation correction can be achieved by using 6D registration without a rotational correction in the selection of patient positioning. This was demonstrated for typical rotation errors seen in clinical practice.
本研究的目的是评估实际旋转摆位误差对颅内立体定向放射治疗（SRT）剂量分布的影响，以及不同治疗位置选择方法的效果。回顾性评估了18例患者的38次SRT治疗，获取实际治疗中的旋转摆位误差。根据在线锥形束CT（CBCT）图像旋转计划计算机断层扫描（CT）图像，并使用三种不同的患者定位方法重新计算旋转后CT图像的剂量分布：1）自动6D匹配，忽略旋转校正（Auto6D）；2）自动3D匹配（Auto3D）；3）基于实际治疗的手动3D匹配（Treat3D）。原始计划的平均适形指数（CI）为0.92，Auto6D计划为0.91。Auto3D计划和Treat3D计划的平均CI分别显著降低（p < 0.01）至0.78和0.80。计划靶区（PTV）的平均最小剂量在原始计划中为处方剂量的91.9%，Auto6D计划中为92.1%，而Auto3D计划和Treat3D计划中PTVmin显著降低（p < 0.01），分别降至78.9%和80.2%。Auto6D与原始治疗计划在剂量参数方面无显著差异。然而，Auto3D和Treat3D计划在统计学上显著劣于Auto6D和原始计划（p < 0.01）。此外，在Auto3D和Treat3D病例中，旋转误差与CI、PTVmin或大体肿瘤体积的最小剂量之间存在显著负相关（p < 0.01，|r| > 0.38）。在SRT中，通过在患者定位选择中使用无旋转校正参数的6D配准，可以实现与6D旋转校正质量相当的治疗计划。临床实践中典型的旋转误差证明了这一点。
