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Objectives: Accurate image registration is vital in cervical cancer where changes in both planning target volume (PTV) and organs at risk (OARs) can make decisions regarding image registration complicated. This work aims to determine the impact of a dedicated educational tool compared with experience gained in MR‐guided radiotherapy (MRgRT). Methods: 10 therapeutic radiographers acted as observers and were split into two groups based on previous experience with MRgRT and Monaco treatment planning system. Three CBCT‐CT, three MR‐CT and two MR‐MR registrations were completed per patient by each observer. Observers recorded translations, time to complete image registration and confidence. Data were collected in two phases; prior to and following the introduction of a cervix registration guide. Results: No statistically significant differences were noted between imaging modalities. Each group was assessed independently pre‐ and post‐education, no statistically significant differences were noted in either CBCT‐CT or MR‐CT imaging. Group 1 MR‐MR imaging showed a statistically significant reduction in interobserver variability (p=0.04), in Group 2, the result was not statistically significant (p=0.06). Statistically significant increases in confidence were seen in all three modalities (p≤0.05). Conclusions: At The Christie NHS Foundation Trust, radiographers consistently registered images across three different imaging modalities regardless of their previous experience. The implementation of an image registration guide had limited impact on inter‐ and intraobserver variability. Radiographers' confidence showed statistically significant improvements following the use of the registration manual. Advances in knowledge: This work helps evaluate training methods for novel roles that are developing in MRgRT. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the consistency of therapy radiographers performing image registration using cone beam computed tomography (CBCT)-CT, magnetic resonance (MR)-CT, and MR-MR image guidance for cervix cancer radiotherapy and to assess that MR-based image guidance is not inferior to CBCT standard practice. 10 patients receiving cervix radiation therapy underwent daily CBCT guidance and magnetic resonance (MR) imaging weekly during treatment. Offline registration of each MR image, and corresponding CBCT, to planning CT was performed by five radiographers. MR images were also registered to the earliest MR interobserver variation was assessed using modified Bland–Altman analysis with clinically acceptable 95% limits of agreement (LoA) defined as ±5.0 mm. 30 CBCT-CT, 30 MR-CT and 20 MR–MR registrations were performed by each observer. Registration variations between CBCT-CT and MR-CT were minor and both strategies resulted in 95% LoA over the clinical threshold in the anteroposterior direction (CBCT-CT ±5.8 mm, MR-CT ±5.4 mm). MR–MR registrations achieved a significantly improved 95% LoA in the anteroposterior direction (±4.3 mm). All strategies demonstrated similar results in lateral and longitudinal directions. The magnitude of interobserver variations between CBCT-CT and MR-CT were similar, confirming that MR-CT radiotherapy workflows are comparable to CBCT-CT image-guided radiotherapy. Our results suggest MR–MR radiotherapy workflows may be a superior registration strategy. This is the first publication quantifying interobserver registration of multimodality image registration strategies for cervix radical radiotherapy patients. [ABSTRACT FROM AUTHOR]