Digital fluoroscopy quality control measurements

The aim of this work was to perform quality control (QC) on three digital fluoroscopy systems used for cardiovascular, digital subtraction angiography (DSA) and digital spot imaging (DSI). Measurements were based on the QC protocol developed in the framework of European Commission (EU) DIMONDIII project. Initially, measurements were performed on a digital fluorography system used for DSI. Measurements included beam quality (half-value layer, HVL), peak tube voltage (kV) accuracy and reproducibility, tube-current exposure-time product (mAs) linearity and automatic brightness control (ABC). Then, patient dose and image quality were measured for the two digital fluoroscopy systems using a patient equivalent phantom. Spatial resolution was measured using the Huettner Type 53 spatial frequency grating. A contrast detail phantom CDRAD 2.0 was used to measure the threshold contrast detail performance. The results show that the measured HVL and peak tube voltage were within the recommended limits of 10%. Maximum patient entrance surface dose (ESD) rate of 27.8 mGy min^-1, 46.5 mGy min^-1 and 84.1 mGy min^-1 (values differ from those in Table 4) were measured using a 20 cm thick polymethylmethacrylate (PMMA) phantom at the cardiovascular unit operated in low, normal and high dose mode of operation, respectively. ESD rate of 28 mGy min^-1 and 42.2 mGy min^-1 (values differ from those in Table 4) were measured using a 20 cm thick PMMA phantom at the DSA unit operated in pulsed and continuous mode of operation, respectively (lowest value should be for pulsed mode). These values are in reasonable agreement with internationally established reference levels. The median limiting resolution was 1.6 lp mm^-1 for image intensifier field diameters between 14 and 38 cm. Mean low contrast resolution expressed as image quality figure (IQF) was 107. The values can be used as baseline for future studies.