The increasing role of functional visualization modalities for navigation of external beam radiation therapy and brachytherapy in prostate cancer

Brachytherapy is successfully used in the treatment of malignant neoplasms in males and females and rare cases in children, as an independent method (with localized prostate cancer) or adjuvant with remote focal radiation therapy (with cancer of the cervix, anal canal, head and neck, breast, etc.). The expansion of diagnostic capabilities (the advent of computer and magnetic resonance imaging) due to three-dimensional imaging has given brachytherapy an important technological advantage over other methods. Many options are available for combining brachytherapy with remote radiation or systemic antitumor therapy in the first line, as well as in a single mode for localized tumor recurrence in a previously irradiated area. Intrastates (hollow tubes) for intra-tissue high-dose brachytherapy are administered during surgery and encapsulated (closed) radioactive micro-sources for low-dose brachytherapy are directly administered (percutaneously). A distinctive feature of brachytherapy is a sharp drop in the dose outside the tumor focus, which minimizes the risk of irradiation of surrounding organs and tissues. The main advantage of brachytherapy in comparison with remote radiotherapy is a higher radiation dose gradient at the tumor border (from all sides). Moreover, clarifying the boundaries of uncertainty when irradiating the target is unnecessary. When the tumor changes during treatment, the sources fixed in the tumor synchronously change their position. In addition to the advantages in efficiency and safety, the total financial costs of brachytherapy are significantly lower than other radiotherapy options.