目的：通过与两个成熟的SRS平台比较，评估ZAP-X立体定向放射外科（SRS）治疗单发脑转移瘤的剂量学特征。
方法：回顾性选择13例接受Cyberknife（CK）G4治疗的单发脑转移患者。计划目标体积（PTV）的处方剂量为1-3分的18-24Gy。PTV体积范围从0.44到11.52cc。使用ZAP-X计划系统和伽玛刀（GK）ICON计划系统以相同的处方剂量和危险器官（OAR）约束对13名患者的治疗计划进行了重新检查。对于ZAP-X和CK，PTV的处方剂量均归一化为70％，而GK为50%。三组的剂量学参数包括计划特征(CI，GI，GSI,梁,MU,治疗时间)，PTV(D2,D95,D98,Dmin,Dmean,覆盖范围)，脑组织(体积100%-10%处方剂量照射V100%-V10%,Dmean)和其他OAR(Dmax，Dmean),对所有这些进行了比较和评价.读取所有数据并用MIMMaestro进行分析。进行了单因素方差分析或多样本弗里德曼秩和检验，其中p<0.05表示显著差异。
结果：GK的TheCI明显低于ZAP-X和CK。关于平均值，ZAP-X的GI较低，GSI较高，但是三组之间没有显着差异。ZAP-X的MU明显低于CK，ZAP-X治疗时间的平均值明显短于CK。对于PTV，CK的D95、D98和目标覆盖率较高，GK的Dmin均值明显低于CK和ZAP-X。对于脑组织，ZAP-X显示从V100%到V20%的较小体积；V60%和V50%的统计结果显示ZAP-X和GK之间存在差异，而V40％和V30％在ZAP-X和其他两组之间显示显着差异；V10％和Dmean表明GK更好。不包括脑干的Dmax,右视神经和视交叉,所有其他OAR的平均值均小于1Gy。对于脑干，GK和ZAP-X有更好的保护，尤其是在最大剂量。
结论：对于SRS治疗单发脑转移瘤，所有三个治疗装置，ZAP-X系统,CyberknifeG4系统,和GammaKnife系统，能满足临床治疗要求。新平台ZAP-X可以提供与赛波刀和伽玛刀相当甚至更好的高质量计划，ZAP-X具有一定的剂量优势，特别是具有更适形的剂量分布和更好的保护脑组织。随着ZAP-X系统的不断改进和升级，它们可能成为治疗脑转移瘤的新的SRS平台。
OBJECTIVE: To evaluate the dosimetric characteristics of ZAP-X stereotactic radiosurgery (SRS) for single brain metastasis by comparing with two mature SRS platforms.
METHODS: Thirteen patients with single brain metastasis treated with CyberKnife (CK) G4 were selected retrospectively. The prescription dose for the planning target volume (PTV) was 18-24 Gy for 1-3 fractions. The PTV volume ranged from 0.44 to 11.52 cc.Treatment plans of thirteen patients were replanned using the ZAP-X plan system and the Gamma Knife (GK) ICON plan system with the same prescription dose and organs at risk (OARs) constraints. The prescription dose of PTV was normalized to 70% for both ZAP-X and CK, while it was 50% for GK. The dosimetric parameters of three groups included the plan characteristics (CI, GI, GSI, beams, MUs, treatment time), PTV (D2, D95, D98, Dmin, Dmean, Coverage), brain tissue (volume of 100%-10% prescription dose irradiation V100%-V10%, Dmean) and other OARs (Dmax, Dmean),all of these were compared and evaluated. All data were read and analyzed with MIM Maestro. One-way ANOVA or a multisample Friedman rank sum test was performed, where p < 0.05 indicated significant differences.
RESULTS: The CI of GK was significantly lower than that of ZAP-X and CK. Regarding the mean value, ZAP-X had a lower GI and higher GSI, but there was no significant difference among the three groups. The MUs of ZAP-X were significantly lower than those of CK, and the mean value of the treatment time of ZAP-X was significantly shorter than that of CK. For PTV, the D95, D98, and target coverage of CK were higher, while the mean of Dmin of GK was significantly lower than that of CK and ZAP-X. For brain tissue, ZAP-X showed a smaller volume from V100% to V20%; the statistical results of V60% and V50% showed a difference between ZAP-X and GK, while the V40% and V30% showed a significant difference between ZAP-X and the other two groups; V10% and Dmean indicated that GK was better. Excluding the Dmax of the brainstem, right optic nerve and optic chiasm, the mean value of all other OARs was less than 1 Gy. For the brainstem, GK and ZAP-X had better protection, especially at the maximum dose.
CONCLUSIONS: For the SRS treating single brain metastasis, all three treatment devices, ZAP-X system, CyberKnife G4 system, and GammaKnife system, could meet clinical treatment requirements. The newly platform ZAP-X could provide a high-quality plan equivalent to or even better than CyberKnife and Gamma Knife, with ZAP-X presenting a certain dose advantage, especially with a more conformal dose distribution and better protection for brain tissue. As the ZAP-X systems get continuous improvements and upgrades, they may become a new SRS platform for the treatment of brain metastasis.
PDF(Pubmed)