Influence of a long air gap and a ratio 15:1 antiscatter grid on pediatric fluoroscopy and angiography image quality

Objective X-ray angiography and fluoroscopy systems are used to diagnose and treat congenital heart disease in pediatric patients. Among the substantial variabilities in this clinical patient population is that patient weight ranges from <1 kg premature infants to large adolescents. The primary aim of this work was to assess whether an air gap or antiscatter grid is more efficient to mitigate the detrimental influence of scatter radiation on pediatric image quality. Approach The experimental approach was guided by a 2 year review of pediatric patient imaging conditions. Uniform density water-equivalent phantoms with thickness in the range 6-24 cm were used. For each phantom thickness, the X-ray technique was manually set to mimic the technique selected by automatic dose rate control. The influence of four combinations of air gap and ratio 15:1 antiscatter grid on test object SNR was measured. The air gap was varied by changing the X-ray source to detector distance from 107 to 120 cm. The analytical methods estimated pixel-specific snr2 contributions to object SNR2, thus providing for the use of iodine disks and pediatric implantable devices as test objects. Main results Patient weight ranged from 0.5 to 134 kg. The relationship between patient water equivalent thickness and weight was demonstrated. For all phantom thicknesses, object SNR was highest using a long air gap, non-grid technique. Decreasing the air gap between the phantom and detector and use of the anti-scatter grid both degraded SNR. These major findings were consistent between iodine disks and clinical devices as test objects. Significance The findings of this phantom study suggest that a long air gap, non-grid imaging technique may improve radiation dose efficiency of fluoroscopy and angiography imaging across a broad range of pediatric patient sizes. .