An approach to iodine quantitation using digital fluorography

Abstract

A technique is suggested for quantitative estimation of contrast medium in human organs using digital subtraction fluorography.A reference wedge of tin is placed in the x-ray field for one of two mask images. The subtracted sequence then contains a set of reference pixel values which can be used as calibration data for the administered contrast medium.The factors affecting quantitative measurement are discussed and experimental estimates of errors made. The characteristics of veiling glare in the system were measured and the effectiveness of a deconvolution algorithm demonstrated.Pixel values corresponding to various thicknesses of a tin reference wedge were compared with those corresponding to thicknesses of tin in a test wedge positioned within a phantom to simulate the patient. Differences between pixel values were measured for variations in several radiographic parameters. Frame-to-frame changes in x-ray output were minimised by using the modal pixel value in the image as a background reference.An estimation of mass thickness of known iodine solutions was made using the technique. In the range 0.5-20.0 mg cm" iodine, the mean estimated value was 0.8 mg cm-2 lower than nominal, with an uncertainty of 1.1 mgcm".

Dose optimization in cardiac x‐ray imaging

“…The authors previously found a marginal difference ( 5%) between contrast measurements with the test details placed at the entrance, exit, or midpoint of the phantom. Tin was used due to the similarity of its x-ray attenuation characteristics compared with iodine contrast material used clinically 22,39 and copper was used to simulate stent and guide wire materials. Air kerma rates and ESD rates were measured using a 20X6-6 and 20X6-60E ionization chamber (Radcal Corporation, Monrovia, USA) respectively with a 2026C Radcal dosimeter.…”

Dose optimization in pediatric cardiac x‐ray imaging

“…Tin ͑Sn͒ has similar x-ray attenuation characteristics to iodine, which makes it a useful and practical surrogate to measure contrast. 40 Using the same sets of imaging conditions, the effect of antiscatter grid removal was also explored.…”

Signal and contrast to noise ratio evaluation of fluoroscopic loops for interventional fluoroscope quality control

“…While this phantom was not one singular phantom, collectively the slabs were only used as an initial proof of concept for SNR and CNR testing methodology. A rectangular tin foil swatch (50 mm × 50 mm × 0.05 mm thick) was employed as a target for CNR measurements and utilized as a surrogate for an iodinated contrast agent, similar to the method described by Kotre et al The tin swatch (Goodfellow Corporation, Coraopolis, PA, USA) was placed directly on top at the center of the first 2.54 cm slab of PMMA (Fig. ) and imaged with clinically used programs, at 7.5 pulses per second (pps), at maximum Source To Image Distance (SID), and with the table top at the Interventional Reference Point.…”