Tomotherapy – a different way of dose delivery in radiotherapy

Aim of the study: Helical tomotherapy is one of the methods of radiotherapy. This method enables treatment implemen tation for a wide spectrum of clinical cas es. The vast array of therapeutic uses of helical tomotherapy results directly from the method of dose delivery, which is sig nificantly different from the classic method developed for conventional lin ear accelerators. The paper discusses the method of dose delivery by a to motherapy machine. Moreover, an analy sis and presentation of treatment plans was performed in order to show the ther apeutic possibilities of the applied tech nology. Dose distributions were ob tained for anaplastic medulloblastoma, multifocal metastases to brain, vulva can cer, tongue cancer, metastases to bones, and advanced skin cancer. Tomothera py treatment plans were compared with conventional linear accelerator plans. Results: Following the comparative analysis of tomotherapy and conven tional linear accelerator plans, in each case we obtained the increase in dose distribution conformity manifested in greater homogeneity of doses in the ra diation target area for anaplastic medul loblastoma, multifocal metastases to brain, vulva cancer, metastases to bones, and advanced skin cancer, and the re duction of doses in organs at risk (OAR) for anaplastic medulloblastoma, vulva cancer, tongue cancer, and advanced skin cancer. The time of treatment delivery in the case of a tomotherapy machine is comparable to the implementation of the plan prepared in intensity-modulated ra diotherapy (IMRT) technique for a con ventional linear accelerator. In the case of tomotherapy the application of a frac tional dose was carried out in each case during one working period of the machine. For a conventional linear ac celerator the total value of the fractional dose in the case of anaplastic medul loblastoma and metastases to bones was delivered using several treatment plans, for which a change of set-up was nec essary during a fraction. Conclusion: The obtained results confirm that tomotherapy offers the possibility to obtain precise treatment plans to gether with the simplification of the ther apeutic system.