Patient skin doses in complex cardiac procedures

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1 S1.P16 Patient skin doses in complex cardiac procedures R. Borisova* 1, J. Vassileva 2, V. Gelev 3, A. Doganov 3 1 Tokuda Hospital Sofia, Sofia, Bulgaria 2 National Centre of Radiobiology and Radiation Protection, Sofia, Bulgaria 3 University Hospital N. I. Pirogov, Sofia, Bulgaria *Presenting author: r.borisova@gmail.com International Conference on Radiation Protection in Medicine 1-3 September 2010, Varna, Bulgaria

2 Introduction Skin injuries have been an issue of growing importance in patient protection in interventional cardiological procedures. Skin erythema is an actual concern especially in cases of chronic total occlusion arteries that have been completely occluded for greater than 30 days. Maximum skin dose (MSD) is the quantity directly related to skin injury occurrence probability. However, its measurement is not always feasible. Efforts have been invested to relate MSD to other dose parameters available in real time during the procedure in order to avoid deterministic skin effects.

3 Purpose to explore the maximum skin doses that patients receive during complex coronary procedures to test two methods for patient skin dose measurement: Gafchromic XR film and Kodak Ready pack EDR2 to establish correlation between maximum skin dose and more readily available parameters such as kerma-area product P KA and cumulative dose CD

Materials and methods KODAK Ready pack EDR 2 Responsive range: 25 400 cgy, app. saturation at 7 Gy GAFCHROMIC XR-R Responsive range: 0.

4 Materials and methods KODAK Ready pack EDR 2 Responsive range: cgy, app. saturation at 7 Gy GAFCHROMIC XR-R Responsive range: cgy, self-developing film, no post-processing required kerma-area product (P KA ) cumulative dose (CD) GE Innova 2100 with a flat panel detector Eight complex cases of chronic total occlusions (CTO) One EDR2 and one Gafchromic positioned under patient s back during the procedure. Also recorded: fluoro time (FT) number of images (N)

5 Materials and methods GAFCHROMIC Calibration pieces of the film exposed to different doses on an angio unit and a conventional radiography unit at approximately 80 kv for the range Gy pieces scanned on a simple flatbed scanner only the red part of the image is used for calibration 0 Gy 0.5 Gy 1 Gy 2 Gy 3 Gy 4 Gy 5 Gy 6 Gy 7 Gy 7.5 Gy

6 Results No FT, min Number of images P KA, Gy.cm 2 Total Cine Fluoro CD, Gy MSD, Gy AV: Average MSD for complex CTO cases is 6 Gy and ranges from below 1 Gy to as much as 11 Gy!

7 Results Ready pack film is not suitable for skin dose measurements in interventional cardiology in practice saturation exposure is much lower than the reported 7 Gy. Gafchromic Calibration of Gafchromic is very time consuming; curves obtained from field calibration and from the calibration strip are practically the same the strip can be used for evaluation of clinically exposed films. Gafchromic calibration curve Patient No. 1: MSD = 0.7 Gy CD = 1.1 Gy P KA = 62 Gy.cm 2 Field calibration Calibration strip Ready pack

8 Results Maximum skin dose, Gy MSD correlation with cumulative dose: Very weak (R 2 = 0.62) but substantially improved if outlying cases are excluded from the plot. In all cases CD overestimates MSD y = x R² = Cumulative dose, Gy Maximum skin dose, Gy MSD correlation with kerma-area product: Good (R 2 = 0.86), excluding the outliers y = x R² = Kerma-area product, Gy.cm 2 MSD correlation with fluoroscopy time: No correlation at all.

Results Patient follow-up: All patients undergoing interventional cardiological procedures

Despite MSD reaching as high as almost 11 Gy for one of the patients, skin injuries have

Five patients have MSD > 6 Gy, the threshold for main erythema, stated to appear 10 days

9 Results Patient follow-up: All patients undergoing interventional cardiological procedures are scheduled for a follow-up examination one month later. Despite MSD reaching as high as almost 11 Gy for one of the patients, skin injuries have not been reported for any of the eight recorded patients. Five patients have MSD > 6 Gy, the threshold for main erythema, stated to appear 10 days after exposure. Has the erythema faded away by the time of the follow-up visit? Or did the patient fail to identify the injury as related to the procedure?

10 Conclusions Maximum skin dose for 8 complex cases varied between 0.7 and 10.9 Gy with an average of 6.1 Gy. Five cases had MSD > 6 Gy (main erythema threshold). Ready pack films are not suitable for skin dosimetry in interventional cardiology due to their saturation at relatively low doses. Field calibration of Gafchromic films and calibration strip yielded the same result. As field calibration is very time consuming, the strip can be used routinely for evaluation of clinically exposed films. Correlation was found between MSD, cumulative dose and kerma-area product. No correlation was observed between MSD and fluoro time. No radiation injuries were reported for any of the recorded patients. There were either no injuries present, or the patient failed to identify and report them.

Gafchromic XR-RV2 radiochromic films dosimetry in interventional radiology

Gafchromic XR-RV2 radiochromic films dosimetry in interventional radiology A. Neocleous *1, E. Yakoumakis 1, G. Gialousis 2, A. Dimitriadis 1, N. Yakoumakis 3 and E. Georgiou 1 1 Medical Physics Department,