Evaluation of grid performance for thoracic radiography in calves using a portable x-ray unit

Thoracic radiography provides diagnostic assistance in assessing the severity of lung lesions in bovine respiratory diseases. We investigated the effects of grid use on overall image quality for portable thoracic radiography in calves. Thoracic radiographs of the dorsocaudal region were made for 30 calves of various sizes, using three acquisition techniques (digital radiography with no grid, with a 3 : 1 grid, and with an 8 : 1 grid). Overall image quality was graded independently by five veterinarians using a 5-point scale based on the visibility of the thoracic vertebral bodies, thoracic spinous processes, scapulae, proximal third of the ribs, caudal lobar pulmonary vessels, and aortic arch; and on the level of image noise. The results were evaluated using Visual Grading Characteristics analysis. The 3 : 1 grid significantly improved overall image quality, regardless of body size. The 8 : 1 grid improved image quality only for calves smaller than 30 cm in thickness. The results of this study support the value of a 3 : 1 grid for portable thoracic radiography in calves.