Trigger levels to prevent tissue reaction in interventional radiology procedures

Abstract

It is well known that the large use of fluoroscopy in interventional radiology procedures may induce unintended patients' skin injuries. For that reason assessment of skin dose for these procedures is getting more and more important. Aim of the study is to investigate the role of cumulative air kerma (CK) as on-line dose indicator and to evaluate the possibility to define a local CK trigger level which can help operators to identify situations with high probability to exceed a peak skin dose of 2 Gy, the threshold dose for transient skin erythema. Cerebral angiography, aneurysm embolisation and chemoembolisation of liver cancer have been identified as the interventional procedures where high skin doses could be delivered. Dosimetric data (CK, air kerma area product (KAP) and fluoroscopy time) have been collected in a sample of procedures and peak skin dose (PSD) have been measured from dose distributions measured with large area radiochromic films (Gafchromic, IPS, USA) located between table top and patient. PSD varied in very wide range and in a few cases were close to the threshold for main erythema and epilation (6 Gy). The correlations between PSD and CK have been successfully assessed for each procedure type and a trigger level for CK has been derived to alert the interventionalist on the probability to have reached a PSD of 2 Gy. In our center trigger levels of 5200 mGy and 2500 mGy has been established for brain aneurysm embolisation and chemoembolisation procedures respectively. As suggested by ICRP in the publication No. 85, a follow-up for patients whose estimated peak skin dose was 3 Gy or greater has been implemented as a routine practice. © 2009 Springer-Verlag.