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In its theoretical part, the bachelor's thesis describes the anatomy of the respiratory system, the types of lung cancers, their symptoms, risk factors and possible treatment. It mainly focuses on lung radiotherapy itself and lung irradiation techniques with regard to the current technical possibilities of radiotherapy. The practical part is represented by the analysis of data from a questionnaire survey examining, in particular, the frequency of the presence of risk factors in patients with lung cancer treated at the RTO of the České Budějovice Hospital. The research part was treatment by questionnaire, the group of patients consisted of a total of 60 respondents. The obtained data were subsequently evaluated with MS Excel tools. In addition to the presence of smoking as the main risk factor, attention was also paid to other risk factors, e.g. occupational stress, general lifestyle or long-term residence in areas with increased radon content in the subsoil. The results confirmed that long-term tobacco smoking remains the most represented risk factor. The processing of answers from the questionnaire also ensures the assumption that a non-negligible risk is also a long-term stay in areas with an increased radon index. The bachelor's thesis can serve as a comprehensive study material for future radiology assistants as an overview of modern lung cancer radiation treatment. But it can also be used in professional articles in magazines, or be a source of information for those interested in this topic.

This bachelor's thesis deals with 4D radiotherapy. Four-dimensional conformal radiotherapy, or 4D radiotherapy, focuses on the position of an irradiated volume at the current time, which changes mainly due to respiratory movements. Its main principle is the synchronization of radiation with "changing - moving target volume". It is used in treating patients with chest tumors, lung cancers and left-sided breast cancer. The technique of irradiation of 4D radiotherapy is Respiratory gating simultaneously using image-controlled radiotherapy. The theoretical part of the thesis describes the individual elements of the process of preparation for irradiation, evaluation of the irradiation plan, verification processes in radiotherapy and modern irradiation methods of 3D conformal radiotherapy. The theoretical processing of the topic, a key part of the thesis, describes the methods and properties of 4D radiotherapy, treatment planning, lists indications suitable for 4D radiotherapy and a describes the fractionation of treatment. In the practical part of this thesis, the irradiation plans of patients treated with 4D radiotherapy at the Radiotherapy Department of Nemocnice České Budějovice, a.s. are compared with irradiation plans obtained from more conventional 3D radiotherapy. In this department, one of the methods of 4D radiotherapy called deep inspiration breath hold (DIBH), has been used since 2019. The objective of the practical part was to demonstrate the benefit of using 4D radiotherapy in the irradiation of left breast cancer, comparing the doses to critical organs (heart, lungs, spinal cord) of patients treated with Respiratory gating with critical organs doses of randomly selected patients treated with conventional 3D radiotherapy. The results of this thesis and the methodology of the workplace mainly pointed out that the choice of 4D radiotherapy is subjected to a consistent selection of patients. The Respiratory gating technique should not be used in patients who are affected by irregular or difficult breathing or insufficiently by the departure of the chest wall from the heart when inhaled. The conclusion of the thesis supports a trend commonly found in the literature describing the advantage of using Respiratory gating in left-sided breast cancers to reduce radiation toxicity to the heart. This may represent, for example, the development of ischaemic heart disease or myocardial fibrosis. It is therefore necessary to pay attention to modern methods that try to eliminate this undesirable consequence of breast irradiation.