Avrum Nathaniel Pollock MD, Presenter: Nothing to Disclose

Xiaowei Zhu, Abstract Co-Author: Nothing to Disclose

To better aid clinicians in understanding available options and dose performance of fluoroscopic units (FU). Using a series of phantom measurements, the possible effects upon Entrance Skin Exposure (ESE) and Dose Area Product(DAP) in pediatric patients, from various dose and pulse modes employed in fluoroscopy, were assessed.

Using an ionization chamber, quantitative dose measurements were performed on a Philips EasyDiagnost FU. ESE rates were measured under various dose(DM) (full(FD), reduced(RD), pediatric(PD), and pediatric combined with reduced (PCR)) and pulse modes(PM) (continuous(CP), 15 pulse per second (PPS), 7.5 PPS, 3.75 PPS) using a 15-cm Lucite phantom placed between the X-ray source and the image intensifier (I.I.) to simulate a typical VCUG in a small child. At the end of each 1 minute fluoroscopic exposure, DAP data were collected from the control consol. Measurements were also taken with collimations under both “open (OC)” and “tight (TC)” conditions.

The data revealed the significant differences in ESE rates and DAP from various DM and PM. For dose modes at large FOV, the % reduction of ESE rates in comparison to FD at equal pulse rates, is in the range of 30-61% under the “OC”; and in the range of 16-58% for “TC”. The DAP reductions (ranging from 8%-56%) from FD to various other DM are similar when measured under the “OC” and “TC”. The PCR mode offers the most effective DAP reduction. For various PM at large FOV, the % reduction of ESE rates in comparison to the “CP”, under the same DM conditions, is in the range of 9-70% for “OC”; and in the range of 8-69% for “TC”. The DAP reductions (from 2% to 65%) are similar for “OC” and “TC”.

DM and PM selection have significant impact in ESE rates and DAP. ESE rates and DAP can be decreased if proper DM and PM are selected.

ESE directly affects patients skin dose, which is very important, especially during long fluoroscopic procedures. DAP reflects overall radiation risk to the patients from the procedure, and should be minimized when possible.

Pollock, A, Zhu, X, Understanding the Fluoroscopic Unit Part I: The Effects of Dose Mode and Pulse Mode.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5011430.html