EuroSafe Imaging 2020
Action 7 - Radiation protection of children, Biliary Tract / Gallbladder, Interventional non-vascular, Liver, Fluoroscopy, Dosimetry, Equipment, Radiation safety, Foetus, Not applicable, Performed at one institution
R. Gerasia, G. S. Gallo, L. Maruzzelli, C. Cannataci, R. Miraglia
Description of activity and work performed
To protect the uterus from external scattered radiation (scatter emanating from the exposed tissue or imaging equipment) the patient’s abdomen with the exception of the right upper quadrant, was wrapped in two lead aprons (0.5 mm lead equivalent).To monitor her equivalent dose at the depth of 10 millimeters (Hp10), two electronic personal dosimeters (EPD MK2, Thermo Fisher Scientific) were positioned above and below the aprons.
The procedure was performed in a monoplane flat-panel-based detector angiographic suite using a postero-anterior projection. The angiographic equipment used was the GE Innova 2100, an angiographic suite targeted for interventional cardiology procedures, which had been in use for 9 years. It was not possible to perform the procedure on the angiographic suite used for the bilioplasty (GE Innova 4100) because this had been dismantled in the interim to make way for a new angiographic suite. However, experience and expert knowledge of the GE Innova 4100 allowed for the appropriate modification of protocols on the GE Innova 2100.
To minimize patient exposure as possible, out of five different fluoroscopic trajectories available, the one chosen for the procedures used only 35% (the lowest option available) optimized to produce low noise images. In addition, because the equipment used allows the choice between adult and pediatric settings for the same auto exposition trajectory, the pediatric setting was chosen so as to lower kV and mA while maintaining the same dose threshold and the same image characteristics. (Figure 3)
The equipment table was kept as far from the source as possible to reduce skin entry dose, while the patient was positioned as close to the image detector as possible. The “Last Image Hold” function was used to store fluoroscopic images, tight collimation was employed such that the field of view was restricted only to the liver and no magnification was used during procedure. (Figure 4)
The lowest possible frame rate available on the angiographic system (7.5 frame/sec) with low image detail level was employed. The anti-scatter grid was removed. DAP (Gy*cm2) and AK (Gy) of the procedures were measured with a dual channel DIAMENTOR M4-KDK DAP/Dose meter transmission ion chamber fixed to the collimator of the angiographic equipment.
The patient’s effective dose and the uterus equivalent dose (in mSv) were extrapolated by the medical physicists using Monte Carlo PCXMC software. (Figure 5)