VERTEBRAL DIMENSIONS - INFLUENCE OF X-RAY TECHNIQUE AND PATIENT SIZE ON MEASUREMENTS

In this study a new reference value, ''corrected vertebral dimension,' ' is presented for vertebral height measurements. Of 68 females (age 1 8-88 years; mean 44.2 years) and 40 males (age 16-81 years; mean 55 ye ars) the projected vertebral dimensions (T-4-L-5) were measured on lat eral radiographs. In addition to this, the vertebra-to-film distances (VFD) were measured and a fixed focus-to-film distance (FFD) was used during the study. Corrected dimensions of the thoracic and lumbar vert ebrae (T-4-L-5) were calculated using the FFD and VFD. These corrected dimensions were then used to recalculate projected vertebral dimensio ns at different focus-to-film distances. The applied geometric correct ions were verified in a phantom study repp resenting an in vitro situa tion. The results indicate that studies using different X-ray techniqu es for making lateral radiographs of the spine can become comparable w hen using corrected vertebral dimensions.