During vertebral operation is suited for the bow root of the body to make the installation of the screw which easy, around the bow root in order and being decisive method of the bow root section, in the cross section of three dimensional picture of the body, internal and touches to the crust surface of its adjacent bow root the series which obtain each front line step and the series which vis-a-vis each front line it crosses, inside the bow root and through its adjacent body, extends obtains the consecutive each second line which is adjacent with the step which, mutually each second line which mutually largest angleThe step which identifies the bow root section the step which identifies around the bow root with as the territory of the crust surface which becomes and, and as a territory of the crust surface where each second line which opposes mutually becomes mutually parallel and, the decisive method of including. The center of the bow root section is identified from the cross section of the above-mentioned bow root section, as the point which 2 it is led from each center of each second orthogonal line where crosses mutually from each minute point from the above-mentioned crust surface each line crosses.脊椎手術の間に椎体の椎弓根に適したスクリューの設置を容易にするための、椎弓根周辺および椎弓根峡部の決定方法であって、椎体の三次元画像の横断面における、椎体内およびその近傍の椎弓根の外皮表面に接する一連の各第一線を得るステップと、一連の各第一線に対して直交する、椎弓根内およびその近傍の椎体を通して延びる一連の各第二線を得るステップと、互いに隣り合う各第二線が互いに最大の角度となる外皮表面の領域としての椎弓根周辺を同定するステップと、および互いに対向する各第二線がお互いに平行となる外皮表面の領域としての椎弓根峡部を同定するステップと、を含む決定方法。椎弓根峡部の中心は、上記椎弓根峡部の横断面から、上記外皮表面からの各微小ポイントからの互いに直交する各第二直交線の各中心から導かれる2本の各ラインの交差する点として同定される。
