Gamma Knife radiosurgery for numerous brain metastases: is this a safe treatment?
OBJECTIVE
Gamma Knife (GK) radiosurgery has recently been employed in patients with numerous brain metastases (METs), even those with 10 or more lesions. However, cumulative irradiation doses to the whole brain (WB), with such treatment, have not been determined.


METHODS
Since the GammaPlan ver. 5.10 (ver. 5.31 is presently available, Leksell GammaPlan) became available in November 1998, 92 GK procedures have been performed for 80 patients with 10 or more brain METs at our facility. The median lesion number was 17 (range: 10-43) and the median cumulative volume of all tumors was 8.02 cc (range: 0.46-81.41 cc). The median selected dose at the lesion periphery was 20 Gy (range: 12-25 Gy). Based on these treatment protocols, the cumulative irradiation dose was computed.


RESULTS
The median cumulative irradiation dose to the WB was 4.71 (range: 2.16-8.51) Gy. The median brain volumes receiving >2 Gy, >5 Gy, >10 Gy, >15 Gy, and >20 Gy were 1105 (range 410-1501) cc, 309 (46-1247) cc, 64 (13-282) cc, 24 (2-77) cc, and 8 (0-40) cc, respectively.


CONCLUSIONS
The cumulative WB irradiation doses for patients with numerous radiosurgical targets were not considered to exceed the threshold level of normal brain necrosis.
Katsuta Hospital Mito GammaHouse, Hitachi-naka, Japan. BCD06275@nifty.com
Masaaki
M
Yamamoto
Mitsunobu
M
Ide
Shin ichi
Si
Nishio
Yoichi
Y
Urakawa
D001921:Brain / Q000473:pathology* / Q000528:radiation effects*; D001932:Brain Neoplasms / Q000473:pathology* / Q000601:surgery*; D006801:Humans; D009336:Necrosis; D009362:Neoplasm Metastasis; D016634:Radiosurgery / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*