The determination of the average patient skin dose and its factors affecting in cardiac catheterization procedures

Abstract

The patient dosimetry for cardiac catheterization and in this study were determined using Dose Area Product (DAP) method. The skin dose was calculated from DAP meter readout and information from portal film determination. The proposed potential factors affecting patient dose are fluoroscopic time, kVp, mAs, patient BMI, number of frames and experience of the cardiologists. The measurement was carried out from 73 patients who underwent the cardiac catheterization procedures such as Diagnostic Coronary Angiography (DCA), Cardiac intervention; Percutaneous Transluminal Coronary Angioplasty (PTCA) /stent and cardiac radiofrequency (RF) ablation at King Chulalongkorn Memorial Hospital. The result shows the average patient skin dose from DCA was 9.52 cGy (95 % confident interval (CI) : 8.39-14.24) in tube A (Postero-Anterior) and 18.67 cGy (95 % CI : 13.97-23.85) in tube B (Lateral), PTCA/stent was 35.95 cGy (95 % CI: 24.50-49.92) in tube A and 85.42 cGy (95 % CI: 40.75-132.96) in tube B. For cardiac RF ablation the average patient skin dose was 64.82 cGy (95 % CI: 42.27-87.43) for single plane. Factors influencing the patient skin dose in this study were fluoroscopic time, kVp, mAs and number of frames. The patient skin dose is more dependent on the fluoroscopic time than other factors especially from DCA, PTCA/stent and RF ablation which the correlation (r is 0.60, 0.83, 0.90, 95% CI : 2.41-8.19, 3.07-6.03, 1.54-2.52, p-value < 0.05) respectively. The average patient skin doses in this study were less than threshold dose of skin injury (2 Gy). Only two patients received the dose higher than the threshold dose (2.12, 4.51 Gy) from cardiac RF ablation and cardiac interventional studies respectively. The benefits of this study are the record and the establishment of the patient skin dose in order to protect the patient from skin injury and increase the cardiologist's awareness for cardiac catheterization procedure.