To compare dosimetric data of stereotactic body radiation therapy (SBRT) plans with CyberKnife (CK) ,Tomotherapy (Tomo) and volumetric-modulated arc therapy (VMAT) for spine bone metastasisof tumor.

Clinical data of 30 spine bone metastasismalignant tumor patients were retrospectively analyzed. The treatment plans were designed by three apparatuses and transferred to MIM system. Prescription dose: the gross tumor volume was 24 Gy points in 2 times, with the primary goals of Maintaining the max tolerance of the cord (17 Gy) or cauda equine (20 Gy) and the plan target volume (PTV) to receive at least 95% of the prescribed dose. The extraction of parameters mainly included conformity index (CI) , homogeneity index (HI) , gradient index (GI) , target volume coverage, maximum cord (or cauda) dose, and treatment time per fraction.

PTV mean D2% coverage in VMAT was significantly lager with Tomo (P<0.01 )and CK (P<0.01). The CI and HI in CK were significantly lower with Tomo and VMAT (all P<0.01 ). The best GI was found in CK, followed by Tomo, and VMAT showed the worst (all P<0.01 ). VMAT had the least treatment time vs Tomo (P<0.01 )and CK (P<0.01).

All three radiotherapy apparatuses can meet the requirement of SBRT for spine bone metastasis of malignant tumor. More rapid dose fall-off could be obtained in CK. VMAT provide better target conformity. The parameters of Tomo are in the middle. The treatment time of VMAT and Tomo are much shorter than CK. The suitable radiotherapy system can be selected according to the characteristics of cases and target areas.

Dose distribution; CyberKnife; Tomotherapy; Accelerator volumetric-modulated arc therapy; Tumor metastasis, spine bone/stereotactic body radiotherapy