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Usage possibilities of the Leksell gama knife.
RYVOLA, Lukáš
Leksell gamma knife is currently a full-fledged part of stereotactic radiosurgery and can be useful in treating many diseases. The uniqueness of this therapy lies in one-time disease-site focused radiation treatment without the need of surgical incision. A single applied dose leads to inducing several times higher radiobiological effect contrary to fractionated radiotherapy, where radiation dose is applied in several fractions. Radiosurgery is not limited by radiosensitivity of targeted lesion, but by its volume. Therefore lesions measuring up to 3 cm in diameter are suitable for gamma knife radiation treatment. Due to its technical construction the Leksell gamma knife is used in the area of the head, while the farthest accessible point in caudal direction is 16,5 cm from head vertex. The process of gamma knife radiosurgical treatment can be divided into several partial stages. In the first phase of the treatment, the doctors are taking diagnostic images using screening methods (CT, MRI, PET, angiography) with marked location of targeted lesion. In the computational matrix, dose distribution setting in the lesion and its vicinity follows. In the third phase, dimensions of the head are determined with the help of a plastic spherical helmet concentric with stereotactic frame. The specialists place the helmet on the base of the frame to measure the distance from skull to the plastic helmet surface using a gauge. Simultaneously, tissue thickness from frame centre to head surface is determined. The last phase symbolises the beginning of the medical procedure itself. The doctor applies local anaesthetic before the stereotactic frame is put on, which must be sufficiently fixated with screws to avoid shifting. Radiation treatment is carried out afterwards. The aim of this bachelor thesis is to analyse the number of patients and the most common diagnoses we can encounter due to Leksell gamma knife treatment, and also carry out an analysis of adverse effects of the above mentioned therapy. The above mentioned analysis of literature and statistical data from the Department of Stereotactic and Radiation Neurosurgery at the Na Homolce Hospital was supposed to answer the research question, whether the number of indications for Leksell gamma knife treatment is increasing. Comparison of available literature with statistical data showed that circle of indications still remains unchanged, although some are in experimental stages; however, they're not applied in clinical practice yet. Furthermore, we can say that particularly in the field of malign and benign tumours, especially for meningiomas and metastatic tumours, the number of patients who underwent Leksell gamma knife treatment is constantly increasing.In conclusion, the research question was answered and defined objectives were achieved. The results of this bachelor thesis can serve to students of the Radiological assistant program as further educational material.
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