Automated noncoplanar treatment planning strategy in stereotactic radiosurgery of multiple cranial metastases: HyperArc and CyberKnife dose distributions.

The purpose of this study was to evaluate and compare the dosimetric effects of HyperArc-based stereotactic radiosurgery (SRS) and a robotic radiosurgery system-based planning using CyberKnife for multiple cranial metastases. In total, 11 cancer patients with multiple cranial metastases (3 to 5 tumors) treated with CyberKnife were examined. These patients were replanned using HyperArc (Varian Medical Systems, Palo Alto, USA). HyperArc plan were designed using 4 noncoplanar arc single-isocenter VMAT in 6 MV flattening filter free mode for simulated delivery with the True beam STx (Varian). The prescription dose was 23 Gy at single fraction. Dosimetric differences and blinded clinician scoring differences were evaluated. Conformity index (CI) and gradient index (GI) were 0.60 ± 0.11 and 3.94 ± 0.74, respectively, for the CyberKnife plan and 0.87 ± 0.08 and 5.31 ± 1.42, respectively, for the HyperArc plan (p < 0.05). Total brain V12-gross tumor volumes (GTVs) for the CyberKnife and HyperArc plans were 5.26 ± 2.83 and 4.02 ± 1.71 cm3, respectively. These results indicate that HyperArc plan showed better CI and total brain V12-GTV, while CyberKnife plan showed better GI. A blinded physician scoring evaluation did not show significant differences between CyberKnife and HyperArc plans. The HyperArc-based SRS plan is comparable with the CyberKnife plan, suggesting a greater potential to emerge as a suitable tool for SRS of multiple brain metastases.

Kadoya N ，Abe Y ，Kajikawa T ，Ito K ，Yamamoto T ，Umezawa R ，Chiba T ，Katsuta Y ，Takayama Y ，Kato T ，Kikuchi Y ，Jingu K ... -  《-》

Linac-based VMAT radiosurgery for multiple brain lesions: comparison between a conventional multi-isocenter approach and a new dedicated mono-isocenter technique.

Ruggieri R ，Naccarato S ，Mazzola R ，Ricchetti F ，Corradini S ，Fiorentino A ，Alongi F ... -  《Radiation Oncology》

Dosimetric performance of two linear accelerator-based radiosurgery systems to treat single and multiplebrain metastases.

Ueda Y ，Ohira S ，Yamazaki H ，Mabuchi N ，Higashinaka N ，Miyazaki M ，Teshima T ... -  《-》

Noncoplanar VMAT for Brain Metastases: A Plan Quality and Delivery Efficiency Comparison With Coplanar VMAT, IMRT, and CyberKnife.

Zhang S ，Yang R ，Shi C ，Li J ，Zhuang H ，Tian S ，Wang J ... -  《-》

Dosimetric effect of rotational setup errors in stereotactic radiosurgery with HyperArc for single and multiple brain metastases.

In stereotactic radiosurgery (SRS) with single-isocentric treatments for brain metastases, rotational setup errors may cause considerable dosimetric effects. We assessed the dosimetric effects on HyperArc plans for single and multiple metastases. For 29 patients (1-8 brain metastases), HyperArc plans with a prescription dose of 20-24 Gy for a dose that covers 95% (D95% ) of the planning target volume (PTV) were retrospectively generated (Ref-plan). Subsequently, the computed tomography (CT) used for the Ref-plan and cone-beam CT acquired during treatments (Rot-CT) were registered. The HyperArc plans involving rotational setup errors (Rot-plan) were generated by re-calculating doses based on the Rot-CT. The dosimetric parameters between the two plans were compared. The dosimetric parameters [D99% , D95% , D1% , homogeneity index, and conformity index (CI)] for the single-metastasis cases were comparable (P > 0.05), whereas the D95% for each PTV of the Rot-plan decreased 10.8% on average, and the CI of the Rot-plan was also significantly lower than that of the Ref-plan (Ref-plan vs Rot-plan, 0.93 ± 0.02 vs 0.75 ± 0.14, P < 0.01) for the multiple-metastases cases. In addition, for the multiple-metastases cases, the Rot-plan resulted in significantly higher V10Gy (P = 0.01), V12Gy (P = 0.02), V14Gy (P = 0.02), and V16Gy (P < 0.01) than those in the Ref-plan. The rotational setup errors for multiple brain metastases cases caused non-negligible underdosage for PTV and significant increases of V10Gy to V16Gy in SRS with HyperArc.

Sagawa T ，Ohira S ，Ueda Y ，Akino Y ，Mizuno H ，Matsumoto M ，Miyazaki M ，Koizumi M ，Teshima T ... -  《Journal of Applied Clinical Medical Physics》