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4D radiotherapy
RYBÁKOVÁ, Aneta
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.
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