Influence of the antiscatter grid on dose and image quality in pediatric interventional cardiology X-ray systems

Objective To present a methodology and experimental results to assess the influence, in terms of dose and image quality, of the antiscatter grid (AG) in a pediatric cardiology X-ray system. Method Entrance surface air kerma and image quality, using a test object and different added thicknesses of polymethyl methacrylate (PMMA), for three different acquisition protocols, were measured with and without the AG, for fluoroscopy and cine modes. The image quality parameters, signal-to-noise ratio (SNR), high-contrast spatial resolution (HCSR) and two figures of merit (FOM) were evaluated. Results The average bucky factor values measured during this experiment were 1.99, 2.49, 2.85, and 3.30, respectively for 4, 8, 12, and 16 cm of PMMA. SNR variations do not appear to be relevant when removing the AG. However, the use of AG improves HCSR significantly. Imaging the test object with 4 cm of PMMA seems appropriate without the AG, but for 8 cm (equivalent to chest thicknesses of 12 cm) and greater thicknesses, a good image quality would require the use of AG. Conclusions The AG should not be used for neonates and very young children with chest thicknesses equal to or less than 6 cm and weight less that 6 kg.