Abstract
Objectives:The radiographical process of projection of a complex human form onto a two-dimensional image plane gives rise to distortions and magnifications. It is important that any simulation used for educational purposes should correctly reproduce these. Images generated using a commercially available computer simulation widely used in radiography education (ProjectionVRTM) were tested for geometric accuracy of projection in all planes.Methods:An anthropomorphic skull phantom was imaged using standard projection radiography techniques and also scanned using axial CT acquisition. The data from the CT was then loaded into the simulator and the same projection radiography techniques simulated. Bony points were identified on both the real radiographs and the digitally reconstructed radiographs (DRRs). Measurements sensitive to rotation and magnification were chosen to check for rotation and distortion errors.Results:The real radiographs and the DRRs were compared by four experienced observers and measurements taken between the identified bony points on each of the images obtained. Analysis of the mean observations shows that the measurement from the DRR matches the real radiograph +1.5 mm/−1.5 mm. The Bland Altman bias was 0.55 (1.26 STD), with 95% limits of agreement 3.01 to −1.91.Conclusions:Agreement between the empirical measurements is within the reported error of cephalometric analysis in all three anatomical planes. The image appearances of both the real radiographs and DRRs compared favourably.Advances in knowledge:The commercial computer simulator under test (ProjectionVRTM) was able to faithfully recreate the image appearances of real radiography techniques, including magnification and distortion. Students using this simulation for training will obtain feedback likely to be useful when lessons are applied to real-world situations.
Highlights
The ability to ‘produce accurate and correct images’ is seen by qualified radiographers as one of the most important competencies
The accurate projection and collimation of an image was seen as the most important technical competency by radiographers with less than 5 years’ experience. Gaining this competence is not trivial; more than 200 unique diagnostic radiographic projections are in standard use.[2]. It is an important area of training, as having to repeat a radiographic exposure is a major cause of increased risk to patients in projection radiography.[3]
This analysis of the mean observations shows that the measurement from the digitally reconstructed radiographs (DRRs) matches the real radiograph +1.5 mm/−1.5 mm
Summary
The ability to ‘produce accurate and correct images’ is seen by qualified radiographers as one of the most important competencies. Andersson et al (2012) surveyed 406 qualified staff of all levels of experience This competence was scored as the sixth priority out of the 29 competencies evaluated.[1] In the same study, the accurate projection and collimation of an image was seen as the most important technical competency by radiographers with less than 5 years’ experience. Gaining this competence is not trivial; more than 200 unique diagnostic radiographic projections are in standard use.[2] It is an important area of training, as having to repeat a radiographic exposure is a major cause of increased risk to patients in projection radiography.[3] Findings of major studies suggest that it is errors in patient positioning, centring and collimation that are the main reasons radiographic examinations are repeated.[4,5,6] These repeats are implicated in increased risks, and patient dissatisfaction, reduction in capacity and increased waiting times. The most frequently occurring repeated examination types are shoulder, hip, spines, in-d epartment chest, skull/ facial bones and pelvis.[7]
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