Verification of target volume position in radioterapy

This Bachelor thesis is concerned with the verification of the target volume setup in radiotherapy. With respect to technological advancement, the necessity to use verification systems for ensuring a quality treatment is highlighted. In its theoretical part, the objective of this Bachelor thesis is to summarize and delineate the imaging technologies used to verify the target volume setup. The objective of the practical part is to analyse deviations in the position of the target volume in IMRT technique for prostate radiation; the analysis is primarily directed at new functions in the correction of the position of the radiation table. The theoretical part of the thesis presents facilities used to verify the target volume and summarizes information relating to the two basic methods in radiotherapy: teletherapy and brachytherapy. Differences between X-ray and radionuclide irradiators and particle accelerators are explained. A brief description is given as to the structure of a linear accelerator, with a summary of irradiation techniques applied in radiotherapy. The data for the practical part were derived from results gained by the correction of the position of the target volume in verification imaging at the Radiotherapy Department in České Budějovice Hospital. For the analysis of deviations, a set of 50 patients who were treated for prostate cancer at the Radiotherapy Department in 2018 was selected. During radiotherapy, excepting daily MV-kV imaging, the total of 417 verification CTs was developed for these subjects. Based on these CT images, the deviation in directing the target volume was evaluated and the appropriate correction of the radiation table, and the given patient as well, was performed. The correction of the radiation table allows for the movement of six axes in total, as described in detail in the present thesis. The results gained from the data collected reveal that the correction of the setup of the irradiated volume is a necessity and it is amply used, specifically in all of the six axes. It was discovered that the functions of the table Lat, Lng, Rnt and Vrt are used at virtually all times, and in concrete terms, the newer function of the table Pitch is utilized at 95,03%, with the use of function Roll standing at 92,64%. The daily verification CBCT was performed in 10% of the patients in the set observed. The standard frequency of the use of the verification CBCT at the Radiotherapy Department in České Budějovice Hospital, for patients irradiated to prostate, is approximately 7 - 9 CBCT during the treatment, which includes a CBCT examination at the first setup and then twice during the first week of treatment, and subsequently only once a week during the radiotherapy procedure. The analysis results proved an abundant use of newly introduced options in the correction of the position of the radiation table, and in general, also an improvement in accuracy of directing the target volume. The improvement in accuracy, and therefore an improvement of quality of the administered radiation therapy, allows for changes in the size of the recorded target volumes, specifically the reduction in these volumes. As a consequence, it is logical that the volume of healthy irradiated issue is smaller, which brings (or might bring) for the patient a decrease in the occurrence or level of seriousness of undesired radiotherapy effects. The results of the research and its findings may serve for evaluating the quality of the verification process in radiotherapy, linked with installation of new technologies in the given healthcare department, or, as the case may be, as data and information to be used for preparation of articles published in specialized magazines