Dosimetric comparison of Zap-X and CyberKnife stereotactic radiosurgery for single brain metastasis
10.3760/cma.j.cn113030-20221124-00393
- VernacularTitle:立体定向放射外科Zap-X与CyberKnife治疗单发脑转移瘤的剂量学比较
- Author:
Jinyuan WANG
1
;
Chengcheng WANG
;
Baolin QU
;
Shouping XU
;
Zhongjian JU
;
Longsheng PAN
;
Xiangkun DAI
Author Information
1. 解放军总医院第一医学中心放射治疗科，北京 100853
- Keywords:
Neoplasm metastasis, brain;
Stereotactic radiosurgery;
Zap-X;
CyberKnife;
Dosimetric comparison
- From:
Chinese Journal of Radiation Oncology
2023;32(9):820-828
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To evaluate the dosimetric characteristics of Zap-X system and CyberKnife (CK) G4 system of stereotactic radiosurgery (SRS) for single brain metastasis.Methods:Twelve patients with single brain metastasis had been treated with CK were selected retrospectively. The prescribed dose of planning target volume (PTV) was 18-24 Gy for 1-3 fractions. The PTV was ranged from 0.44 to 11.52 cm 3. The 12 patients were re-planned in the Zap-X planning system using the same prescription dose and organs at risk constraints, and the prescription dose of PTV was normalized to 70% for both Zap-X and CK. The planning parameters and dosimetric parameters of PTV and organs at risk were compared and evaluated between two plans. All data were read at MIM Maestro. A paired Wilcoxon' signed-rank test was adopted for statistical analysis. A P value of less than 0.05 was considered as statistical significance. Results:For the target coverage, CK was significantly higher than Zap-X (99.14±0.57% vs. 97.55±1.34%, P<0.01), but Zap-X showed a higher conformity index (0.81±0.05 vs. 0.77±0.07, P<0.05), a lower Paddick gradient index (2.98±0.24 vs. 3.15±0.38), and a higher gradient score index (GSI) than CK. The total monitor unit (MU) of Zap-X was significantly lower than that of CK (11 627.63 ±5 039.53 vs. 23 522.16 ±4 542.12, P<0.01) and the treatment time was shorter than that of CK [(25.08 ±6.52) vs. (38.08 ±4.74) min, P<0.01]. Zap-X had lower dose volumes than CK for the dose of brain ( P<0.05). Zap-X had a lower D mean and D max of brainstem (both P<0.05), but a higher value of eyes and lens. For optic nerves and optic chiasm, there were no significant differences between two groups. In addition, for the protection of skin (V 22.5 Gy), Zap-X seemed better than CK [(4.15±4.48) vs. (4.37±4.50) cm 3, P<0.05]. Conclusions:For SRS treating single brain metastasis, Zap-X could provide a high quality plan equivalent to or even better than CK, especially reducing the treatment time. With continuous improvement and upgrading of Zap-X system, it may become a new SRS platform for the treatment of brain metastasis.
