20.500.12556/RUL-169989 Deviation of the upper, middle and lower thirds of the rectum during irradiation of rectum cancer Background In patients with rectal cancer, daily fluctuations in rectal volume often lead to large deformations of the target volume that cannot be corrected by adjusting the radiation couch. The main aim of the study was to determine the deviation of all three thirds of the rectum from the reference position and to determine whether these deviations are influenced by the alignments to the bony structures (the sacrum) and the posterior rectal wall. Patients and methods The conduct of the study was divided into review of the database, contouring of the anatomic structures on the cone-beam computed tomography (CBCT) images, data collection of the deviations and data output, with the alignment to the bony structures (the sacrum) - and the alignment to the posterior rectal wall performed separately. Results Fifty preoperatively irradiated patients were included in the study. The analysis revealed statistically significant differences in terms of alignment to the bony structures for different variations of the rectal thirds in the anterior (+), posterior (+), posterior (−), left (−), right (+) and right (−) directions. With regard to the alignment to the posterior rectal wall, the analysis showed statistically significant differences for different variations of the rectal thirds in directions anterior (+), posterior (+), posterior (−), left (−), right (+), right (−) and bone (+). (The positive value (+) means that the rectum was larger and the negative value (−) means that the rectum is smaller than in the reference position of the CT simulator images.) Conclusions The position of the rectal thirds changes daily in alignment with the bony structures (the sacrum), and in alignment with the posterior rectal wall. rectal movement rectal cancer preoperative radiotherapy radiotherapy true false true Angleški jezik Ni določen Članek v reviji 2025-07-01 10:54:11 2025-07-01 10:54:12 2025-07-02 04:07:20 0000-00-00 00:00:00 2025 0 0 Str. 277-284 no. 2 Vol. 59 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 2025-01-01 616-07 1581-3207 10.2478/raon-2025-0020 240925443 Deviation-of-the-upper,-middle-and-lower-thirds-of-the-rectum-during-irradiation-of-rectum-cancer.pdf Deviation-of-the-upper,-middle-and-lower-thirds-of-the-rectum-during-irradiation-of-rectum-cancer.pdf 1 4D841A4859D2961D3DEB384D3CAA768F 06c3040707cab103aee81ba84c2a47d7d02595b04aeee34a7ce6e3b80b0525a4 4dbf092a-5657-11f0-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=211885 https://sciendo.com/article/10.2478/raon-2025-0020 1 120c4004-5657-11f0-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=211884 Zdravstvena fakulteta Medicinska fakulteta 0 0 0