Effects of scatter correction processing on image quality of portable thoracic radiography in calves

Thoracic radiography provides diagnostic assistance in assessing the severity of lung lesions in bovine respiratory diseases. We investigated the effects of a novel scatter correction processing software on the image quality of portable thoracic radiography in calves: this scatter correction method was recently developed for mobile bedside chest radiography in humans. Thoracic radiographs of the caudodorsal region were obtained from 30 calves of various sizes. Scatter correction processing of a grid ratio of 3 : 1 or 8 : 1 was applied to each image. The delineation of caudal thoracic vertebral bodies, scapulae, proximal third of the ribs, pulmonary vessels, and the aortic arch, as well as overall image quality were graded by five veterinarians using 5-point scales. Three types of images (original and scatter-corrected with grid ratios of 3 : 1 and 8 : 1) were compared using visual grading characteristics analysis. Scatter correction with a grid ratio of 3 : 1 improved the overall image quality, at least for calves with a body thickness of ≤40 cm, and improved the delineation of some anatomical structures for larger calves. Scatter correction with a grid ratio of 8 : 1 did not improve the delineation of any anatomical structures examined for calves ＞40 cm in thickness or the overall image quality for calves ＞30 cm in thickness. The present findings support the efficacy of scatter correction processing with a grid ratio of 3 : 1 for portable thoracic radiography in calves

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

DEVELOPMENT OF FPGA-BASED TDC WITH WIDE DYNAMIC RANGE FOR MONITORING THE TRIGGER TIMING DISTRIBUTION SYSTEM AT THE KEKB INJECTOR LINAC

Abstract A new field-programmable gate array (FPGA)-based time-to-digital converter (TDC) with a wide dynamic range greater than 20 ms has been developed to monitor the timing of various pulsed devices in the trigger timing distribution system of the KEKB injector linac. The pulsed devices are driven by feeding regular as well as any irregular (or event-based) timing pulses. For monitoring the timing as precisely as possible, a 16-ch FPGA-based TDC has been developed on a Xilinx Spartan-6 FPGA equipped on VME board with a time resolution of 1 ns. The resolution was achieved by applying a multisampling technique, and the accuracies were 2.6 ns (rms) and less than 1 ns (rms) within the dynamic ranges of 20 ms and 7.5 ms, respectively. The various nonlinear effects were improved by implementing a high-precision external clock with a built-in temperaturecompensated crystal oscillator