The purpose of this study is to define a site and procedure specific trigger levels, using online dose indicator, able to inform the interventional radiologist when the peak skin dose (PSD) has reached a value of 2 Gy during the procedure. In this way, the radiologist can consider the benefit-risk balance taking into account the possibility that the skin of the patient is at risk for delayed erythema or other implications [1]. It is extremely relevant to define these values locally due to the wide variability of the methodology in performing the procedure, the X-ray equipment and operator’s skills.

In most cases, during the procedure, the angiographic systems provide information on the cumulative air-kerma (K_a,r) at the interventional reference point (IRP) [2] or on the Air-Kerma Area product (KAP), while the PSD is not available. These indicators do not map the skin dose distribution nor assess the PSD, which is  the most useful index to identify potential adverse effects. Instead, in those centres where software for skin dose map estimation is not available or for older equipment, K_a,r and KAP remain a PSD estimator [3].

The NCRP (National Council on Radiation Protection and Measurements) [4] suggests a value of air-kerma of 3 Gy (corresponding to PSD of 2 Gy), to alert that the maximum skin dose is about to reach a Substantial Radiation Dose Level (3 Gy of PSD) and about the possibility of skin injuries.

Nevertheless, the NCRP trigger level is generic: the type of procedure may involve significant variations in the skin dose distribution, for example, in those cases without beam movement (no changes in the position or angle of the radiation field). In Figure 1 two skin dose distribution of two different procedure are compared: they show two different PSD (1.8 Gy for PAE and 5.2 for TIPS) even though they have same KAP (500 Gy·cm2) and K_a,r (2.3 Gy).