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We present our results of 3D CT/MRI brachytherapy (BT) planning in 115 patients with locally advanced cervical cancer T2b-3bN0-1M0. The aim of this study was to assess the differences in the visualization of tumor target volumes and risk organs during the 3D CT/MRI BT. The results of the study revealed that the use of MRI imaging for dosimetric planning of dose distribution for a given volume of a cervical tumor target was the best method of visualization of the soft tissue component of the tumor process in comparison with CT images, it allowed to differentially visualize the cervix and uterine body, directly the tumor volume. Mean D90 HR-CTV for MRI was 32.9 cm3 versus 45.9 cm3 for CT at the time of first BT, p = 0.0002, which is important for local control of the tumor process. The contouring of the organs of risk (bladder and rectum) through MRI images allows for more clearly visualizing the contours, which statistically significantly reduces the dose load for individual dosimetric planning in the D2cc control volume, і.є. the minimum dose of 2 cm3 of the organ of risk: D2cc for the bladder was 24.3 Gy for MRI versus 34.8 Gy on CT (p = 0.045); D2cc for the rectum - 18.7 Gy for MRI versus 26.8 Gy for CT (p = 0.046). This is a prognostically important stage in promising local control, which allows preventing manifestation of radiation damage.

Purpose: To assess the quality of planning for the combined radiotherapy of patients with advanced cervical cancer (cervical cancer). To assess the impact of taking into account not only the external, but also the internal wall of the organ of risk during contouring on the magnitude of the radiation load on the organ of risk (OR). Estimate the total dose to the OR from the remote and intracavitary components.Material and methods: The planning quality assessment was carried out for three technologies of remote exposure, namely: 3DCRT, IMRT and IMRT in the rotational RapidArc mode. Radiotherapy was performed on linac Clinac iX models (Varian, USA) with photon energy of 6 MeV, intracavitary RT (IRT) — on a MicroSelectron apparatus with a 192Ir source. The calculation was carried out on the treatment planning system Eclipse (Varian, USA) and Oncentra Brachy.Results: The evaluation of the quality of conformal radiotherapy planning was carried out in 69 patients with locally advanced cervical cancer 2b–3b stages according to homogeneity and dose conformance indexes in target volumes and OR in combined radiation therapy programs. The best values of the indices of homogeneity and conformity were obtained with the IMRT technology and 3DCRT. The values of the conformity index CI for PTV for the IMRT technology has advantages in terms of doses to OR. For a group of 94 patients, an analysis of dose loads on the rectum, bladder was carried out with only the external contour of the OR and taking into account the inner wall. For 37 patients, the total values of doses to OR for combined RT were evaluated.Conclusion: The quantitative advantages of homogeneity and conformance indices for the tumor and dose loads in OR of 3D CRT and IMRT technologies for patients with cervical cancer 2b–3b are revealed. We removed from the use of technology RapidArc for this group of patients. The advantages of contouring with or without thickness are not revealed. The contouring for all the mentioned cases of technology can be carried out along the outer contours of the OR.