The Human Research Ethics Committee of the Royal Melbourne Institute of Technology (RMIT) University (BSEHAPP 06-15) approved the project, including its design and recruitment methods.
Chiropractic students in the second semester of year four of the program in 2016 were recruited as part of their traditional practical sessions in radiography. Informed consent was obtained in the first test item of an online survey, with respondents able to exit at this point if they so preferred.
Participating chiropractic students were scheduled to attend one laboratory session which used the computer-based virtual radiography simulation software Projection VR™. Projection VR™ simulation in this university setting could be adequately delivered via Windows 8 or 7 (64 or 32 bit) with a graphics processor of at least DirectX and Shader Model 3.0 or 4.0 hardware support and 512 megabytes or more of dedicated video RAM. The standard computer laboratory equipment at the university met or exceeded these requirements.
A worksheet on simulated radiography of the lumbar spine was developed for chiropractic students using Projection VR™. No training was conducted prior to using the simulated radiography system as students learned to use the technology while they undertook the activity under the guidance of an experienced lecturer in radiography. The detailed worksheet allowed the students to use the technology as they undertook the laboratory activity. Each student used the simulation individually.
There were three key areas of focus for this activity. Firstly, for each student to simulate patient positioning and technical set up in preparation for taking the Anterior to Posterior lumbopelvic image and to generate an AP lumbopelvic (APLP) image (Figure 1). Secondly, having produced an unrotated APLP, students were then asked to rotate their patient so that the patient’s right posterior side was closer to the image receptor (Figure 2). Before generating the image, students were asked what distinguishing anatomical features they expected to see on the image (Figure 2). This strategy was used to support active and engage critical thinking as students consciously paused and reflected before they undertook their next action . Thirdly, the effect of exposure factor selection on the digital image as well as patient dose was investigated. This was tested using two methods, namely application of the 15% rule and the effect of decreasing and increasing milliamp seconds (mAs) on digital images. Increasing kilo volt peak (kVp) with a concomitant decrease in mAs is expressed as the 15% kVp rule. The 15% rule states that a 15% increase in kVp is the equivalent of doubling the exposure received at the image receptor [10, 11]. To maintain exposure at the image receptor, the mAs is halved. The increase in kVp, when applying the 15% rule, is variable and dependent on the original kVp. For example, at 60 kVp, the calculated change in kVp is be 9 kVp whereas at 80 kVp, the required change is 12 kVp. Studies examining application of the 15% kVp rule demonstrate a considerable reduction in patient dose (22% - 60%) without adversely affecting image quality [12, 13]. This is an important finding as increasing kVp reduces subject contrast and could therefore potentially negatively impact image quality [10, 11] . Before generating the image acquired using the 15% rule, students were asked what change if any they may expect to see on the image (Figure 3) and what impact, if any, applying the 15% rule would have on patient dose. Technical data available in Projection VR™ relating to radiation dose for the two images generated is provided in Figure 4. Entrance surface dose (ESD) measurements were compared for the two exposure techniques. The final aspect of selection of exposure factors on digital images was undertaken by asking students what difference they would expect to see on the radiographic image and on patient dose if they were to half or double the mAs. Generated images are provided in Figure 5.
Figure 1 Technical set up for Anterior to Posterior lumbopelvic (left) and resultant image generated (right) using Projection VR™
Figure 2 Technical set up for rotated (Right anterior oblique position) Anterior to Posterior lumbopelvic (left) and resultant image generated (right) using Projection VR™
Figure 3 Images generated using Projection VR™ with 15% rule applied. Image on right 81 kVp, 40 mAs and image on left 93 kVp, 20 mAs.
Figure 4 Technical data display available when using Projection VR™ allowing for comparison of Entrance Surface Dose (ESD) with 15% rule applied. Image on right 81 kVp, 40 mAs and image on left 93 kVp, 20 mAs.
Figure 5 Images generated using Projection VR™ at 81 kVp and varying mAs 20 mAs (left), 40 mAs (centre) and 80 mAs (right)
Throughout the session, students were asked to predict the outcome of each change in patient position or exposure factors before they generated and saw images or technical data. This method was used to encourage students to think critically in applying their decision-making skills in a clinical setting and has been found to reinforce learning by other authors [9, 14, 15] .
Evaluation of virtual radiography
Students who were enrolled in the radiographic positioning course in the chiropractic program were invited to participate anonymously in an online Qualtrics survey during the session. The survey comprised a mix of quantitative and qualitative items including Likert scales and open-ended questions. This assessed the ease with which students used Projection VR™ and the extent to which they developed program skills. Survey data were then entered for analysis.
The survey data were entered into SPSS 21.0® and descriptive and inferential statistics were used for analysis. Cross tabulations were performed using age group and gender and self-reported confidence using computer technology to determine if relationships existed. Differences between groups were examined using chi-square analysis and Fisher's exact test.
Analysis of survey data was descriptive only as this research involved an exploratory snap-shot process - that is, the survey was only administered once  .