GAMMA KNIFE SURGERY 1 Years of Clinical Experiences In 1951, Leksell took the concept of using stereotaxy and minimal invasive surgery a giant step forward by introducing the concept of radiosurgery. In radiosurgery the scalpel is replaced by a highly focused radiation beam which produces a lesion at the precisely predetermined target in the brain. Late Professor Lars Leksell defined radiosurgery in 1951 as: "The delivery of a single, high dose of radiation to a small and critically located intracranial volume through the intact skull." In 1968 Professor Leksell developed the first prototype of the Leksell Gamma Knife, which was installed at Sophiahemmet in Stockholm, Sweden. 2 Leksell Gamma Knife C In 1999 Elekta further refined the art of radiosurgery by introducing the Leksell Gamma Knife C. 30 years of clinical experience with extensive clinical research, improvements in diagnostic imaging and advancements in treatment planning have enabled Elekta to further develop and improve Leksell Gamma Knife to become a more efficient tool. 3 A Complete Clinical Concept Elekta has developed the Leksell Gamma Knife into a complete clinical solution - called Gamma Knife surgery. Gamma Knife surgery encompasses all the products and services required for all phases of a radiosurgical program, like; Training and Education System Start-up Leksell Gamma Knife Society Clinical Research Communication Support Treatment Planning System Service and Support 4 Gamma Knife Surgery - The Principles The Leksell Gamma Knife is a dedicated neurosurgical tool for minimally invasive treatment of critically located intracranial targets. Gamma Knife surgery is defined as "the delivery of a single high dose of irradiation to a small and critically located intracranial volume through the intact skull". The 201 individual beams intersect in one focal point. This picture shows the automatic positioning system, an important improvement in the Leksell Gamma Knife C. 5 Leksell Gamma Knife C A cross section of the entire Gamma Knife - showing the cobalt sources, collimators (beam channels), collimator helmet (in both out and treatment position), patient couch and shielding. The principles of the Gamma Knife includes 201 individual fixed cobalt sources. Cobalt has been chosen for its reliability; there are never any uncertainties about the beam's stability or reliability. With cobalt, there is no need for vacuum systems, cooling system, klystrons or complex electronically steered servo systems to keep the beam stable. Further, the radiation sources are stationary, as are the collimators and the isocenter is always stationary in time. This gives extreme precision. It is a dedicated system and it is a uniform treatment modality giving reproducible results. This means that a new Gamma Knife center can rely on the expertise built by other centers over the years. 6 Treatment Procedure The Gamma Knife surgery procedure is straight-forward and is supported by dedicated Elekta products, to give smooth integration between all steps. The procedure consists of: 1) Frame fixation 2) Diagnostic imaging 3) Treatment planning 4) The actual treatment 7 Frame Fixation The first step is the frame fixation and the Leksell stereotactic frame is fixated to the patient using local anesthesia. The purpose of the frame is two-fold. First, it provides a necessary method to accurately fixate the patient during treatment. Secondly, the frame provides the reference system, fixed relative to the head, for the stereotactic coordinate system. An important feature of the Leksell frame is the simplicity of the coordinate system. It is based on the Cartesian coordinate system with X, Y, Z and the treatment planning software, Leksell GammaPlan, automatically locates the fiducials and establishes the coordinate system for each image. The Leksell frame is compatible with CT, MR and Angio imaging without any need for additional attachments and the treatment can be based on MR alone. 8 Diagnostic Imaging The second step in Gamma Knife surgery is the diagnostic imaging. Here the patient is scanned in one or more imaging modalities. MR is the most frequently used modality. The Leksell MR indicator box is designed to fit even inside the smallest headcoil. Images are transferred to the treatment planning system by network digital tape (DAT), or film scanning. 9 Treatment Planning The third step in Gamma Knife surgery is the treatment planning. The diagnostic images are used on a computer workstation to plan the treatment. This is done by planning a series of isocenters directly on the diagnostic images on the screen in order to completely cover the target, while sparing the surrounding tissue. There is also real time point-to-point correlation in all images, giving confirmation of target and critical structures in all images. 10 Treatment The patient with the frame is fixated in the system. Then the surgeon makes a check and confirms that the patient is in the right position. Then the patient goes into treatment position. 11 The Time Factor If we take a case where the symptoms are diagnosed and the case can either be treated by traditional microsurgery or Gamma Knife surgery, we can easily see the advantages in Gamma Knife surgery. 12 Clinical Outcome Gamma Knife surgery is a minimally invasive technique with great advantages and proven clinical outcome with: – fewer complications – reproducible results – documented scientific data – treatment solution for inoperable patients – combined treatment with microsurgery and endovascular techniques extend the capabilities. 13 Treated Indications Listed here are indications currently accepted and proven with over 1000 published articles. For tumors, there are acoustic, meningiomas, pituitary tumors and primary malignancies (such as gliomas) and metastic tumors. For vascular, there are AVM's. For treatment of functional disorder like trigeminal neuralgia, the Gamma Knife has been shown during the last few years to be an effective tool. Presently various research is being performed on functional disorder, like epilepsy etc. 14 A Global Treatment Method Gamma Knife surgery is a homogeneous methodology from a single supplier. Thus, the method of treatment (radiation source, treatment planning, stereotactic fixation, precision etc.) is the same all over the world and one can expect similar results when using a homogeneous method. Today there are more than 134 Gamma Knife centers worldwide (as per January 2000) that can offer Gamma Knife surgery to patients. 15 Cumulative Patients Treated Radiosurgery with the Gamma Knife was first introduced as a clinical methodology in 1968 by the late Professor Leksell. World-wide use has further established Gamma Knife surgery and, today, it is an accepted treatment modality. Clinical planning and treatment protocols are the same, with a homogenous treatment method practised all over the world. By December 1999 the total number of patients treated by the Leksell Gamma Knife was more than 120,000. 16 Quality of Life The list of advantages for Gamma Knife surgery, as compared with other treatment methods, can be summarized by: – minimally invasive treatment method – less trauma – faster recovery – minimal hospitalization – fewer complications – documented efficacy. 17 Elekta Providing Precise Solutions Late professor Lars Leksell stated "the tools used by the surgeon must be adapted the task and where the human brain is concerned they cannot be too refined". Leksell Gamma Knife is one good example of such a tool. 6 GAMMA KNIFE SURGERY 6 (5) JAN 2000 Education & Traing GAMMA KNIFE SURGERY 1 (5) JAN 2000 Education & Training