Patient skin dose assessment during CT-guided interventional procedures

The purpose of this study was to investigate patient skin doses in the most frequent computed tomography-guided interventional radiology procedures. The study includes 14 abdominal biopsies and 15 radiofrequency (RF) ablations. Patient skin dose was assessed by slow verification films. The technical factors recorded were: tube kilovoltage (kV(p)), tube load (mAs), slice thickness and the total number of slices (S). The median value of maximum entrance skin dose (ESD(M)) in biopsy was 108 mGy (9.5-282 mGy). S had a range of 4-152 with a median of 44 slices. Significant correlation was found between S and dose (r = 0.80). Median ESD(M) in RF ablation was 238 mGy (104-500 mGy). S had a range of 108-175 with a median of 155 slices. No significant correlation was found between S and dose. The large range of results show that a more extensive investigation should be performed. In summary, diagnostic procedures such as biopsy present patient skin doses that are relatively low. On the other hand, patient skin dose in RF ablation can be high and can reach values higher than the value that a slow verification film is capable of measuring (1.2 Gy). For these procedures, an alternative method should be investigated.