An investigation into the variability of radiographers assessing body composition prior to CT contrast media administration.

INTRODUCTION: To evaluate and report the variability of radiographers in determining a patient's body type and using this to determine contrast media (CM) volumes for chest computed tomography (CT). METHODS: This prospective study recruited 50 patients undergoing chest CT examinations. Three radiographers independently used two methods to determine patient body type and consequently CM volume. In Method 1, subjective evaluation of body type together with patient weight determined CM volume. In Method 2, patient weight along with additional criteria applied by the radiographer determined CM volume. Both the determination of body type and CM volumes were compared in terms of agreement and variability between radiographers, and between methods. RESULTS: Fleiss' kappa was lower (0.583) for Method 1 when compared to Method 2 (0.926) indicating stronger agreement in the radiographer determination of body type for Method 2. Median (IQR) CM volume was 95.0 mL (85.0-110.0) for Method 1, compared to 92.5 mL (85.0-100.0) for method 2 (P < 0.001). CONCLUSION: Method 2 provided greater agreement in determination of body type, and reduction of CM volumes compared to Method 1. IMPLICATIONS FOR PRACTICE: Determining body type as part of a CT CM strategy can be subjective and enhanced methods are required to ensure that the most appropriate CM volumes are reliably used.

Reduction of visual acuity decreases capacity to evaluate radiographic image quality.

INTRODUCTION: To determine the impact of reduced visual acuity on the evaluation of a test object and appendicular radiographs. METHODS: Visual acuity was reduced by two different magnitudes using simulation glasses and compared to normal vision (no glasses). During phase one phantom images were produced for the purpose of counting objects by 13 observers and on phase 2 image appraisal of anatomical structures was performed on anonymized radiographic images by 7 observers. The monitors were calibrated (SMPTE RP133 test pattern) and the room lighting was maintained at 7 ± 1 lux. Image display and data on grading were managed using ViewDEX (v.2.0) and the area under the visual grading characteristic (AUCVGC) was calculated using VGC Analyzer (v1.0.2). Inferential statistics were calculated using SPSS. RESULTS: For the evaluation of appendicular radiographs the total interpretation time was longer when visual acuity was reduced with 2 pairs of simulation glasses (15.4 versus 8.9 min). Visual grading analysis showed that observers can lose the ability to detect anatomical and contrast differences when they have a simulated visual acuity reduction, being more challenging to differentiate low contrast details. No simulation glasses, compared to 1 pair gives an AUCVGC of 0.302 (0.280, 0.333), that decreases to 0.197 (0.175, 0.223) when using 2 pairs of glasses. CONCLUSIONS: Reduced visual acuity has a significant negative impact on the evaluation of test objects and clinical images. Further work is required to test the impact of reduced visual acuity on visual search, technical evaluation of a wider range of images as well as pathology detection/characterization performance. IMPLICATIONS FOR PRACTICE: It seems that visual performance needs to be considered to reduce the risks associated with incomplete or incorrect diagnosis. If employers or professional bodies were to introduce regular eye tests into health screening it may reduce the risk of misinterpretation as a result of poor vision.