Different gamma knife models offer different technical components to radiosurgery.

     We compared radiosurgical treatment parameters between the Leksell Gamma Knife(LGK) Perfexion(PFX) and previous models(LGK B/C).

     At our center, 495 patients were treated with the LGK B(Jan. 2002 – Feb. 2004). 3,102 patients were treated with the LGK C(Mar. 2004 – May 2010). 803 patients were treated with the PFX(Jun. 2010 – Jul. 2011).

     Treatment parameters were evaluated and compared by measuring the gradient index(GI), conformity index(CI), Paddick conformity index(PCI), selectivity index(SI), beam on time(BT), treatment time, treatment position type, and collision risk.

     In the similar dose rate (range 3.1~3.4Gy/min), the median total time in the treatment room per patient was 56min (BT=53min) for PFX, 77min (BT=40min) for LGK C(C), and 96min (BT=35min) for LGK B(B). In the whole population, The collision check was predicted by GammaPlan for at least one shot in 5.4% of the patients treated with PFX and in 58.8% of the patients treated with C. The collision risk requiring technical adjustment(lateral position mode) was observed in 4.9% of the patients treated with C, and 2.4% of the patients treated with B. Technical failures for at least one shot occurred in 0.4% of the patients with PFX, 1.0% of the patients with C, and 1.0% of the patients with B. In vestibular schwannoma, the median values of GI in PFX, C and B were 2.65, 2.75 and 2.68, respectively. The CI in PFX, C and B were 1.17, 1.32 and 1.25. The PCI in PFX, C and B were 0.79, 0.73 and 0.76. The SI in PFX, C and B were 0.83, 0.75 and 0.78. The coverage and conformity indices were similar with both units.

     This was a retrospective review.

     LGK PFX proved a high efficiency in treatment delivery by comparison with previous models.

     The clinical setting time and the QA procedure were reduced by the PFX.