Modelo para estimar doses acumuladas em tempo real para procedimentos intervencionistas

Abstract

In interventionist procedures that use fluoroscopy, medical staff is exposed to ionizing radiation, often with doses exceeding the recommended limits. These doses are only observed at the end of the procedure, or after one month utilizing individual dosimeters. The objective of the present study was to develop a method to estimate doses of ionizing radiation in realtime during the interventionist medical procedure using fluoroscopy. The performance of the remote-controlled fluoroscopy system in scattered radiation measurements was tested at 50 kV and 30 mA with a Ludlum 9DP ionization chamber and a PMMA phantom. Dose rates were collected by the ionization chamber for the gonad regions at 90 cm, for the hands at 109, for the chest at 128 and the lens of the eyes at 166 cm with the ground level about the beam distances main at 19, 38, 76 and 152 cm, around the 45 to 45-degree fluoroscopy table. To estimate doses in real-time, an ionization chamber was attached to the top of the fluoroscopy table and used as a fixed reference point. The collected data were sent to the developed software to determine the estimated doses. The numerical values of the estimated doses are visualized in real-time using a monitor showing the intensities of the accumulated doses, with a visual indication of the color scale of the doses received by the members of the medical team in the position they are concerning the table To validate the estimate doses in a real-time system, the hypothesis of the measured dose rates and the estimated real-time measures were implemented using Student’s t-test for independent samples with a significance level of 5%. We evaluated the estimate of the equivalent dose in a scattered object during an average time of exposure to scattered radiation in 20 minutes, which corresponds on average to an interventionist procedure, and we find, respectively, the following estimates in the scattered dimension object 30x30x15 cm: for the gonad region at 539, 159, 76, 42, and 22 μSv; for hands at 858, 392, 172, 74 and 22 μSv; for the chest at 539, 282, 152, 98 and 22 μSv; and the lens of the eyes 221, 159, 110, 78 and 22 μSv, which correspond to the X-ray beam distances in 19, 38, 57, 76 and 152 cm respectively around the fluoroscopy table. The results are similar according to the literature. The estimated dose in real-time helps the interventionist physician optimize their exposure to scattered radiation during the intervention procedure, allowing them to enhance personal protection and reduce the occupational dose.