Assessment of the Optic-guided Patient Positioning for Spinal Stereotactic Radiosurgery Using Novalis ExacTrac System

노발리스 ExacTrac system을 이용한 척추 정위 방사선수술 방법 평가

Stereotactic radiosurgery for intracranial lesion is well established since the Lars Leksell first introduced radiosurgery concept in 1951 Its use in the treatment of spinal lesion has been limited by the availability of effective immobilization devices. The first clinical experience of the spinal stereotactic radiosurgery technique was reported by Hamilton AJ. in 1995. Recently, Optic-guided patient positioning technique for extracranial stereotactic radiosurgery was developed and reported. This study is for assess the target positioning accuracy of the optic guided patient positioning system Exactrac (BrainLab., Inc, Germany). We have designed phantom for assess the accuracy of spinal stereotactic radiosurgery The infrared reflective body markers attached to the relatively immobile part of the body and a series of 2 mm CT images was taken. The image sets were transferred to the planning computer. During the radiosurgery treatment, we measure the real-time display showing the positioning values from Exactrac computer. And we compare the isocenter deviation from irradiated center point of the film which was mounted on the lesion site of the phantom and pin hole site of that film. The accuracy of the ExacTrac system in positioning a target point shows enough for the clinical applications.

두개외 병소 즉, 척추 등에 발생한 종양 혹은 혈관기형 등의 병소에 대해 침습적 수술이 불가한 경우 정위적 방사선 수술이 임상에서 시도되고 있다. 본 연구는 실험적으로 팬텀에 대해 척추 정위 방사선수술을 시행하고 결과 분석을 통하여 두개외 수술 목표점에 대한 방사선수술 위치 정확도를 평가하고자 한다. 이 실험을 위하여 팬텀을 특별히 고안하였으며 수술실에서 방사선 수술 목표점의 위치는 광학적 추적 장치를 이용하여 결정하였고 3 mm 미세다엽시준기(mMLC; mcro Multi-Leaf Collimator)를 사용하여 시술하였다. 팬텀의 목표점에 대한 방사선수술 오차는 $\pm$1 mm 이내였으며 분할방사선 수술 경우도 $\pm$1 mm 이내였다. 결과적으로 광학적 위치추적 장치를 이용한 두개외 목표점의 방사선 수술은 매우 정확하고 유용한 방법으로 판단된다.