# The Use of Mixed Reality in Training Trainers--A Single-Centre Study
## 3 Materials and Methods  
A single-centre prospective study was conducted over a 2-year period at Cambridge University Hospitals. Two cohorts of students attending a course on postgraduate certificate on education and clinical research were approached for this study. As part of understanding new technologies in medicine, a dedicated 2-h period was utilised to introduce the use of mixed-reality technology in education. The students were not asked to prepare for this session and no study materials were provided prior to the teaching session.  
For this study, a Microsoft HoloLens 2 was used. After a general introduction of the team's experience with mixed reality [8], a brief demonstration on the use of mixed-reality headsets was given for 15 min. The audience was divided into 3 groups due to the availability of 3 headsets. Two trainers with previous experience in utilising the MR headsets conducted the session.  
One headset was connected to a livestream display of the usage. Computed tomography (CT) of a normal brain, magnetic resonance imaging (MRI) of a large meningioma, a CT of abdomen pelvis, and a 3D-printed cranioplasty scan were displayed using the headset. Anonymized preoperative computed tomography (CT)/magnetic resonance imaging (MRI) obtained from 3 patients admitted to the department was used. Consent was obtained from all patients to utilise their imaging without any identifiers for neurosurgical teaching. The imaging files were uploaded onto the Microsoft Azure Cloud. The images were anonymized prior to uploading and processing. For the purposes of this study, we used Virtual Surgery Intelligence (VSI, VSI HoloMedicine by apoQlar, Hamburg, Germany) Version 1.9 software. VSI provided the software capability for image rendering. It converted the CT and MRI files in Digital Imaging and Communications in Medicine (DICOM) standard into a 3D rendering. VSI did not require the modification of imaging protocols for the rendering of the images. Hence, this software was used for the purposes of the study to look at the feasibility of teaching. Interchanging between all 4 images was carried out to allow the participants to visualise and interact in the mixed-reality environment. The trainees were then asked to complete a post-usage questionnaire in an anonymous fashion. Due to the anonymous and voluntary nature of the survey, ethical approval was not needed.  
Two questionnaires were provided to the trainees after the session. Trainees were allowed to provide anonymous responses. A formalised questionnaire was used to evaluate the possibility of using MR in neurosurgery training (Questionnaire SA). Each question was scaled from 1 to 7, with 1 referring to strongly disagree and 7 referring to strongly agree. This questionnaire was adapted from the study by [PERSON] (2018) [21] that compared traditional teaching modalities with VR. To evaluate the trainee feedback in using a MR platform, the User Experience Questionnaire (UEQ) [22] was employed (QuestionnaireSB). UEQ 7 is a 26-item 7-point scale to understand the user experience in utilising a commercially available device. These values are then converted to negative or positive values, ranging from \(-3\) up to \(+3\). Values between \(-0.8\) and \(0.8\) represent a neutral evaluation of the corresponding scale, values \(>0.8\) represent a positive evaluation, and values \(<0.8\) represent a negative evaluation. The authors have previously utilised the same user feedback in their previous study [8].