[Stereotactic irradiation for brain metastases using linear accelerator].
A stereotactic irradiation (STI) system using a linear accelerator was developed and its effectiveness for brain metastasis was investigated. The system consisted of a conventional linear accelerator, invasive fixation head frame (RADFRAME, Mizuho Ika Kogyo), and a tungsten collimator. The RADFRAME was developed to be used with any linear accelerators and with any dose planning systems. The accuracy of the irradiation was assured to be within +/-1.5mm. Fifty-one patients with metastatic brain tumors were treated using the system. The overall median survival time was 10 months. No difference in survival was observed between patients with a single lesion and patients with two or three lesions. Complete, partial, and minimal responses were obtained in 16 (39%), 18 (41%), and 7 (16%) lesions. These were comparable to the reported results of gamma knife treatment. A maximum dose of 25 Gy was suggested to be more effective than lower doses. Local control rate was higher in tumors with a diameter of less than 2.0cm (87.5%) than in larger tumors (60%). No difference in tumor response was observed among various histopathologic types. In a patient with a 25mm cerebellar metastasis from an adenocarcinoma of the lung, autopsy at 5 months after STI showed fibrinoid degeneration and hyaline deposition without residual tumor at the Gd-enhanced region on MRI. The efficacy of linac stereotactic irradiation was equal to that of gamma knife radiotherapy for metastatic brain tumors.
Kato
T
T
Department of Neurosurgery, Hokkaido University School of Medicine, Sapporo, Japan.
Shirato
H
H
Suzuki
K
K
Takamura
A
A
Tomita
M
M
Nishioka
T
T
Isu
T
T
Miyamachi
K
K
Sawamura
Y
Y
Miyasaka
K
K
Abe
H
H
D000230:Adenocarcinoma / Q000473:pathology; D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000473:pathology / Q000556:secondary* / Q000601:surgery*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010315:Particle Accelerators; D016634:Radiosurgery / Q000295:instrumentation*