20.500.12556/RUL-173359 vOARiability interobserver and intermodality variability analysis in OAR contouring from head and neck CT and MR images Background Accurate and consistent contouring of organs-at-risk (OARs) from medical images is a key step of radiotherapy (RT) cancer treatment planning. Most contouring approaches rely on computed tomography (CT) images, but the integration of complementary magnetic resonance (MR) modality is highly recommended, especially from the perspective of OAR contouring, synthetic CT and MR image generation for MR-only RT, and MR-guided RT. Although MR has been recognized as valuable for contouring OARs in the head and neck (HaN) region, the accuracy and consistency of the resulting contours have not been yet objectively evaluated. Purpose To analyze the interobserver and intermodality variability in contouring OARs in the HaN region, performed by observers with different level of experience from CT and MR images of the same patients. Methods In the final cohort of 27 CT and MR images of the same patients, contours of up to 31 OARs were obtained by a radiation oncology resident (junior observer, JO) and a board-certified radiation oncologist (senior observer, SO). The resulting contours were then evaluated in terms of interobserver variability, characterized as the agreement among different observers (JO and SO) when contouring OARs in a selected modality (CT or MR), and intermodality variability, characterized as the agreement among different modalities (CT and MR) when OARs were contoured by a selected observer (JO or SO), both by the Dice coefficient (DC) and 95-percentile Hausdorff distance (▫$HD_95$▫). Results The mean (±standard deviation) interobserver variability was 69.0 ± 20.2% and 5.1 ± 4.1 mm, while the mean intermodality variability was 61.6 ± 19.0% and 6.1 ± 4.3 mm in terms of DC and ▫$HD_95$▫, respectively, across all OARs. Statistically significant differences were only found for specific OARs. The performed MR to CT image registration resulted in a mean target registration error of 1.7 ± 0.5 mm, which was considered as valid for the analysis of intermodality variability. Conclusions The contouring variability was, in general, similar for both image modalities, and experience did not considerably affect the contouring performance. However, the results indicate that an OAR is difficult to contour regardless of whether it is contoured in the CT or MR image, and that observer experience may be an important factor for OARs that are deemed difficult to contour. Several of the differences in the resulting variability can be also attributed to adherence to guidelines, especially for OARs with poor visibility or without distinctive boundaries in either CT or MR images. Although considerable contouring differences were observed for specific OARs, it can be concluded that almost all OARs can be contoured with a similar degree of variability in either the CT or MR modality, which works in favor of MR images from the perspective of MR-only and MR-guided RT. variability analysis contouring organs-at-risk computed tomography magnetic resonance radiotherapy head and neck cancer analiza variabilnosti orisovanje kritični organi računalniška tomografija magnetna resonanca radioterapija rak glave in vrat true false true Angleški jezik Slovenski jezik Članek v reviji 2025-09-16 15:16:35 2025-09-16 15:16:41 2025-11-08 03:42:57 0000-00-00 00:00:00 2024 0 0 Str. 2175-2186 no. 3 Vol. 51 Mar. 2024 0000-00-00 Zaloznikova Objavljeno apc 0000-00-00 0000-00-00 0000-00-00 004.93 0094-2405 10.1002/mp.16924 181670147 Medical_Physics_-_2024_-_Podobnik_-_vOARiability__Interobserver_and_intermodality_variability_analysis_in_OAR_contouring.pdf Medical_Physics_-_2024_-_Podobnik_-_vOARiability__Interobserver_and_intermodality_variability_analysis_in_OAR_contouring.pdf 1 C8F9738DA0CFB483FEF6C1C70BD372D7 7c0910a4a9cb6d8fdc75bc8341885e1d6605de170fff5acea9b622429fc1e9d9 f58af22c-9301-11f0-9328-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=217757 https://aapm.onlinelibrary.wiley.com/doi/10.1002/mp.16924 1 37f357fd-92ff-11f0-9328-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=217751 Fakulteta za elektrotehniko 0 0 0