Gamma Knife

The Gamma Knife radiosurgery is a method to treat brain tumors. The method was invented in the year 1968 by the Swedish neurosurgeon Lars Leksell and is further developed in the last years.

The stereotactic radiosurgery (SRS) with the Gamma Knife® Perfexion™ system from Elekta AB© is not a classic surgical procedure with a scalpel. Instead, the tumor is treated in one fraction with highly precise radioactive beams which destroy the tumor cells with minimal damage for the surrounding tissue. The method depends on the identical prescriptions as the radiation therapy with linear accelerators which is successfully implemented in our department for a long time.

192 cobalt-60 radiation sources which are focused in one point are responsible for the treatment. The variable positions of the radiation sources allow to resize/modulate the focal point and to generate optimal dose distributions in the tumor with sparing of the normal tissue. The extremely high precision of the device allows to reduce the security margins around the tumor. The use of a stereotactic frame guarantees this high precision. This light weighted frame is fixated to the skull of the patient under local anesthesia and consequently secured against movement. 

Treatment procedure: the patient receives a special diagnostic MRT prior to the irradiation with the Gamma Knife®. Therefore we intensified the close collaboration with the neuroradiology department. The MRT is the foundation for the oncologist and the medical physicist for the treatment planning. A day before the treatment with the Gamma Knife® the patient is admitted to hospital. On treatment day the patient receives the stereotactic frame followed by a high resolution planning computer tomography. The frame functions as coordinate system which is visible on the CT images. After definition of the tumor/s based on the CT images and a fusion with the MRT images, the exact tumor location is determined. Based on these information’s the one-hour treatment planning procedure can start. For this time the patient waits in a special waiting area under supervision of a radiation therapist. Following the planning process the patient is transported to the Gamma Knife® and fixated to the treatment table to enables the high precision treatment.

 

Gamma Knife dose

Figure 1: sample dose distribution of a brain metastasis treatment

 

The treatment is painless for the patient and lasts up to 120 minutes depending on the number, the size and complexity of the tumor/s. The patient is fully conscious while treatment, can listen to music or even sleep. The team of radiation therapist, oncologist and medical physicist observe the patient via video and audio during treatment.

 

Gamma Knife Picture

Figure 2: Treatment unit

 

Directly after the treatment the frame is removed and the patient stays for one more night in the hospital under surveillance. The following day the patient can leave the hospital and will be monitored continuously.

 

Video of the vendor about the Gamma Knife Perfexion: http://www.elekta.com/healthcare-professionals/products/elekta-neuroscience/gamma-knife-surgery/gamma-knife-perfexion.html

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last modified: 06-Jan-17
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