Optimization of beam quality for coronary angiography procedures in Interventional Paediatric Cardiology : a phantom study

Abstract

Background: Coronary angiography procedures deliver a high radiation dose to the patient, with newborns being especially radiosensitive. Current literature on dose optimisation during such procedures does not su ciently re ect the clinical situation. Objectives: To identify x-ray beam quality parameters which optimise the image quality to dose relationship through a clinically relevant setup. Research Design: Investigate the e ect of tube potential, ltration, and Anti-Scatter Grid (ASG) on Entrance Surface Air Kerma (ESAK), E ective dose (ED) and Contrast to Noise Ratio (CNR) using two optimisation Figures of Merit (FOMs): (1) CNR2/ESAK and (2) CNR2/E. Posteroanterior (PA) (0°/0°) and Lateral Anterior Oblique (LAO) (25°/0°) angulations were investigated. Set-up: A CIRS ATOM newborn anthropomorphic phantom was set up on a Siemens Axiom Artis system. A 100 μm thick tin detail simulated iodine contrast. Acquisitions were taken for 50{70 kVp, 0{1mmCu lters and grid in/out. CNR was evaluated through the use of pixel values and an Inverse Look-up-Table (ILUT). ESAK was measured directly while ED was calculated using Monte Carlo software. Results: The ASG was found to reduce FOMs in all cases. Without the grid, FOM (1) values falling in the top 5% (highest in brackets) for PA were 66{70 kVp (66 kVp), 0:6{0:9mmCu (0:6mmCu). For FOM (2): 50{66 kVp (66 kVp), 0:6{0:7mmCu (0:6mmCu). Similarly for LAO: 66{70 kVp (70 kVp), 0:8{0:9mmCu (0:8mmCu) and 60{70 kVp (70 kVp), 0:4{0:9mmCu (0:8 mmCu). Conclusions and recommendations: This study identi ed optimised x-ray beam quality exposure parameters for coronary angiography procedures for newborns for the Siemens Axiom Artis dBC. For newborns, the grid should be removed. In going from a PA to an LAO orientation, where slightly higher tube voltages are favoured, ltration should be increased from 0:6mm to Cu 0:8 mmCu.