[CT-controlled stereotactic operation of hypertensive intracerebral hemorrhage--1. Theoretical principles and the operative procedures].

In recent years, the CT-guided stereotactic operations have been applied to evacuation of intracerebral hematomas or cystic lesions, the biopsy of deep seated brain tumors, and brachytherapy of brain tumors. However, most of these operations utilized stereotactic guide-frame for determination of the coordinates of the target point. In this paper, an operative method for the stereotactic surgery using coordinate system of CT apparatus itself is presented as a novel method with the principles and the actual operative procedures. It may be called as "CT-controlled stereotactic operation" because the surgery should be performed under intraoperative use of CT scanning. The apparatus is composed with two parts: head holder and needle holder, which were reformed MATSUMOTO's stereotactic apparatus with a more wider separation of the two parts. The principles of the aiming of the target are as follows. Values of coordinates of the target point of Xt, Yt, and Zt will be obtained from the CT scan preoperatively. Zt is set to Zero, then values of coordinates of aiming needle are obtained in two points, N1 (X1, Y1, Z1) and N2 (X2, Y2, Z2). Value of coordinates of the X0 and Y0, namely falling points of the needle direction in the plane of XY, will be calculated with the values of X1, Y1, X2, Y2, Z1 and Z2 by a formula. Direction of the needle is corrected until the values of X0 and Y0 are equal to that of Xt and Yt before insertion of the needle.(ABSTRACT TRUNCATED AT 250 WORDS)