Daniel Bednarek PhD, Presenter: Grant, Toshiba Corporation

Vijay Rana, Abstract Co-Author: Nothing to Disclose

Stephen Rudin PhD, Abstract Co-Author: Grant, Toshiba Corporation

To provide a summary of peak-skin dose (PSD) values determined during clinical cardiac catheterization procedures using a custom-dose-tracking system (DTS) and to compare these to dose–related procedure parameters including the cumulative-dose (CD) values provided by the imaging system.

A DTS has been developed that automatically calculates the skin dose to the patient in real time using a computer patient model and the imaging system geometry and exposure parameters obtained from the fluoroscopic system. The system provides a color-coded graphic of the skin-dose distribution and the numerical PSD values. The DTS has been interfaced to a Toshiba Infinix C-Arm unit installed in a cardiac catheterization laboratory and about 65 procedures have been monitored to date. The DTS also records total fluoroscopy and cine exposure times, projection views and technique parameters, which are provided in a report at the end of the procedure. In addition, we manually recorded patient height, weight and DOB, and the C-Arm unit’s display of CD and dose-area-product values. Correlations between these parameters and PSD are evaluated.

PSD values for all cardiac procedures ranged between 124 and 4500 mGy with a median value of 790 mGy, while the CD ranged between 257 and 5250 mGy with a median value of 1560 mGy. The PSD values were generally lower than the FDA-mandated CD displayed value, which is the total air kerma at a reference point and does not consider “dose spreading”. About 10% of procedures resulted in a PSD over 2000 mGy, which is considered to be the threshold for temporary erythema. The ratio of PSD to CD ranged from 0.27 to 1.18 with a median value of 0.55. The wide range of these ratios shows poor correlation between PSD and CD. The large variability between procedures resulted in little correlation between PSD and fluoroscopy time, body mass index or other procedure dose-related parameters.

Insufficient correlation exists between PSD and CD, as well as other dose-surrogate parameters, to justify their use in managing deterministic risk during interventional fluoroscopic procedures.

The ability to track skin dose during interventional fluoroscopic procedures using a system such as we describe is necessary to properly manage patient risk for deterministic radiation effects.

Bednarek, D, Rana, V, Rudin, S, Peak Skin Dose for Cardiac Catheterization Procedures Determined with an Automatic Dose-tracking System.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11012154.html