Greto Daniela, Pallotta Stefania, Masi Laura, Talamonti Cinzia, Marrazzo Livia, Doro Raffaella, Saieva Calogero, Scoccianti Silvia, Desideri Isacco, Livi Lorenzo
Radiotherapy Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, Largo Brambilla 3, 50141, Florence, Italy.
Medical Physics Unit, Azienda Ospedaliero Universitaria Careggi, University of Florence, Florence, Italy.
Radiol Med. 2017 May;122(5):392-397. doi: 10.1007/s11547-017-0735-9. Epub 2017 Feb 15.
Radiosurgery (RS) is a well-established treatment in selected patients with brain metastasis. The aim of this study is to compare the differences between CyberKnife (CK) and TomoTherapy (HT) treatment plans of RS of single brain metastasis (BM) to define when HT should be used in cases beyond Cyberknife-when both systems are readily available for the radiation oncologist.
Nineteen patients with single brain metastasis treated with CK were re-planned for radiosurgery using TomoTherapy Hi-ART system. Two planning approaches have been used for TomoTherapy plans: the classical one (HT) and the improved conformity (icHT) that produces dose distributions more similar to those of RS plans. PTV coverage, Conformity Index (CI), Paddick Conformity Index (nCI), Homogeneity Index (HI), Gradient Index (GI), and beam on time of CK, HT, and icHT plans were evaluated and compared.
A good coverage was found for CK, HT, and icHT plans. A difference between mean HI of CK and icHT plans was observed (p = 0.007). Better dose gradients compared to both icHT and HT modalities were observed in CK plans. icHT modality showed improved mean CI respect to HT modality, similar to that obtained in CK plans.
CK plans show higher conformity and lower GI than icHT and HT plans. TomoTherapy demonstrates the advantage of being a device capable to reach different clinical objectives depending on the different planning modality employed. CyberKnife and TomoTherapy are both optimal RS devices, the choice to use one over another has to be clinically guided.
放射外科（RS）是治疗特定脑转移瘤患者的一种成熟疗法。本研究旨在比较射波刀（CK）和螺旋断层放射治疗（HT）对单发性脑转移瘤（BM）进行放射外科治疗计划的差异，以确定在射波刀无法适用的情况下（当两种系统对放射肿瘤学家都容易获取时）何时应使用HT。
对19例接受CK治疗的单发性脑转移瘤患者，使用螺旋断层放射治疗Hi-ART系统重新制定放射外科治疗计划。HT计划采用了两种规划方法：传统方法（HT）和改进适形度方法（icHT），后者产生的剂量分布与RS计划更相似。评估并比较了CK、HT和icHT计划的靶区适形度（PTV）覆盖情况、适形指数（CI）、帕迪克适形指数（nCI）、均匀性指数（HI）、梯度指数（GI）以及射束开启时间。
CK、HT和icHT计划均有良好的覆盖情况。观察到CK计划和icHT计划的平均HI存在差异（p = 0.007）。与icHT和HT模式相比，CK计划显示出更好的剂量梯度。icHT模式相对于HT模式显示出平均CI有所改善，与CK计划获得的结果相似。
CK计划比icHT和HT计划显示出更高的适形度和更低的GI。螺旋断层放射治疗显示出根据所采用的不同规划模式能够实现不同临床目标的优势。射波刀和螺旋断层放射治疗都是最佳的放射外科设备，选择使用其中一种还是另一种必须以临床为导向。
