Introduction: One of the more recent and effective irradiation techniques is stereotactic body radiotherapy. Such irradiation is a highly accurate technique of external target irradiation outside the skull, where 1 to 8 fractions and high doses per individual irradiation fraction are used. Purpose: The purpose of the diploma work is to determine which intra-fraction movements appear in the anterior-posterior direction, the super-inferior direction and the medio-lateral direction between the planned target volume compared to the actual irradiated volume before the irradiation and after the completed daily fraction of irradiation in the stereotactic irradiation of lung cancer. Methods: We performed a cross-sectional retrospective study. Data were collected at the Oncology Institute in Ljubljana at the radiotherapy department of the irradiation machine (Varian - Novalis Tx). The data were collected from the beginning of May 2016 to the end of November 2017. The study included 25 patients, of which 16 were men and 9 women. For statistical analysis, we used Microsoft Office Excel 2013 and IBM SPSS Statistics 24. Results: The average movement from stereotactic irradiation of the lungs was 0,38 cm in the antero-posterior direction, in the superio-inferior direction 0,33 cm and in the medial-lateral direction 0,24 cm. After the irradiation in the AP plane, the total movement average was 0,12 cm, in the SI plane 0,14 cm and 0,11 cm in the ML direction. Discussion: When examining the results, we found that the maximum average movement before the radiation was in the AP direction, and the smallest average movement was in the ML direction. After irradiation, the largest average movement was in the SI direction and the smallest average movement in the ML direction. We found that movements before irradiation are larger than those after irradiation. Conclusion: By appropriate geometric verification we can confirm that verification procedures for the quality of irradiation are indispensable, because they allow us to minimize the possible deviation from the planned irradiation volume.
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