Primary and secondary brain tumors are tumors of the central nervous system. Each radiotherapy for a patient is planned. Today, the routine procedure for the planning of the brain tumor irradiation comprises the use of computed-tomography simulators together with magnetic resonance simulators. The magnetic resonance simulator is used to improve the contrast and spatial resolution of soft tissue in comparison to the computed-tomographic simulator. Purpose: The goal of this diploma work is to compare the quality of images resulting from magnetic resonance imaging of patients with brain tumors made with two different coils and with different fixation of the patient using our own guidelines for the radiotherapy planning. Methods: In a retrospective study with a secondary data analysis we have analyzed the images of patients with brain tumor at the Institute of Oncology Ljubljana, who were also undergoing the preparations for radiotherapy treatment with a magnetic resonance simulator. We selected a period of three months, from 1 August 2018 to 31 October 2018. Three independent reviewers rated magnetic resonance images following the criteria we had developed for the evaluation of magnetic resonance images. We have processed data using a statistical data processing program. Results: The evaluators did not agree regarding the evaluation of movement artefacts. However, there were no statistically significant differences between the averages of all three evaluators. We have noticed various artefacts, such as artifacts due to pulsation of veins, dental implants, eye movement and pulsing of the cerebrospinal fluid. We have found that regarding more than half of the criteria the highest rated was the HNU face bill coil. Statistical analysis showed a statistically significant difference only regarding the criterion for the assessment of the overall quality of magnetic resonance images pointed out by only one evaluator (p<10-3). Otherwise, we did not find statistically significant differences (p>10-3) between the 6-channel flex coil and HNU face bill coil. Discussion and conclusions: We cannot reliably claim that the type of fixing mask and consequently the choice of the coil affects the presence of movement artifacts. With reference to the quality of MR image it is important that these movements do not interfere with planning of the irradiation. Different quality of the images was due to the different shape of the coils and the number of channels and consequently the different coverage of the taken pictures. Differences in the quality of the images appeared mainly in the area of ??the crown of the head, where the 6-channel flex coil sometimes led to grainy images on some upper cuts. However, the HNU face bill was used for imaging of approximately half as many patients, which may be the reason for better results in the evaluation of magnetic resonance imaging compared to the 6-channel flex coil.
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