|
Stereotactic surgery or stereotaxy (not to be confused with the virtuality concept of ''stereotaxy'') is a minimally invasive form of surgical intervention which makes use of a three-dimensional coordinate system to locate small targets inside the body and to perform on them some action such as ablation, biopsy, lesion, injection, stimulation, implantation, radiosurgery (SRS), etc. In theory, any organ system inside the body can be subjected to stereotactic surgery. However, difficulties in setting up a reliable frame of reference (such as bone landmarks which bear a constant spatial relation to soft tissues) mean that its applications have been, traditionally and until recently, limited to brain surgery. Besides the brain, biopsy and surgery of the breast are done routinely to locate, sample (biopsy) and remove tissue. Plain X-ray images (radiographic mammography), computed tomography, and magnetic resonance imaging can be used to guide the procedure. Another accepted form of "stereotactic" is "stereotaxic". The word roots are ''stereo-'', a prefix derived from the Greek word στερεός (''stereos'', "solid"), and ''-taxis'' (a suffix of New Latin and ISV, derived from Greek ''taxis'', "arrangement", "order", from ''tassein'', "to arrange"). ==Procedure== Stereotactic surgery works on the basis of three main components: * A stereotactic planning system, including atlas, multimodality image matching tools, coordinates calculator, etc. * A stereotactic device or apparatus * A stereotactic localization and placement procedure Modern stereotactic planning systems are computer based. The stereotactic atlas is a series of cross sections of anatomical structure (for example, a human brain), depicted in reference to a two-coordinate frame. Thus, each brain structure can be easily assigned a range of three coordinate numbers, which will be used for positioning the stereotactic device. In most atlases, the three dimensions are: latero-lateral (x), dorso-ventral (y) and rostro-caudal (z). The stereotactic apparatus uses a set of three coordinates (x, y and z) in an orthogonal frame of reference (cartesian coordinates), or, alternatively, a polar coordinates system, also with three coordinates: angle, depth and antero-posterior location. The mechanical device has head-holding clamps and bars which puts the head in a fixed position in reference to the coordinate system (the so-called zero or origin). In small laboratory animals, these are usually bone landmarks which are known to bear a constant spatial relation to soft tissue. For example, brain atlases often use the external auditory meatus, the inferior orbital ridges, the median point of the maxilla between the incisive teeth. or the bregma (confluence of sutures of frontal and parietal bones), as such landmarks. In humans, the reference points, as described above, are intracerebral structures which are clearly discernible in a radiograph or tomograph. In newborn human babies, the "soft spot" where the coronal and sagittal sutures meet (known as the fontanelle) becomes the bregma when this gap closes.〔Carlson, Neil R."Physiology of Behavior".Pearson Education, Inc., 2013. p.134.〕 Guide bars in the x, y and z directions (or alternatively, in the polar coordinate holder), fitted with high precision vernier scales allow the neurosurgeon to position the point of a probe (an electrode, a cannula, etc.) inside the brain, at the calculated coordinates for the desired structure, through a small trephined hole in the skull. Currently, a number of manufacturers produce stereotactic devices fitted for neurosurgery in humans, as well as for animal experimentation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Stereotactic surgery」の詳細全文を読む スポンサード リンク
|