RFA is recommended as a technique for the treatment of early stage (Child A or B, solitary HCC or up to 3 nodules < 3 cm in size) HCC. The best outcomes have been reported in Child-Pugh A patients with small single tumour, commonly less than 2 cm in diameter. When the patient is considered inoperable, RFA can be indicated also in huge tumours, even in combination with other procedures. RF is coagulation induction from electromagnetic energy sources with frequencies less than 30 MHz For tumour ablation purposes the frequency is usually in the 375-500 kHz range. Even if there exist optimistic data concerning survival of the patients with HCC treated by RFA, RFA is "only" palliation with therapeutic potential. After correctly indicating and performing RFA we can expect 5-yr survival in 40-70% and curative treatments in 30% patients. Major complications after percutaneous ablation such as severe pain, neoplastic seeding, intrahepatic abscesses, intestinal perforation, pleural effusion and peritoneal bleeding after RFA have been reported in up to 6% of patients and mortality related to RFA up to 0.3%. The most common complications are abdominal haemorrhage, abscess, biliary tract damage, liver failure, pulmonary complications and ground pad burns. Follow-up imaging studies should be aimed at detecting local tumour progression, the development of new hepatic lesions, or the emergence of extra hepatic disease. A recommended follow-up protocol includes CT or MR examinations at 3-, 6-, 9-, and 12 months after the treatment and at 6-month intervals thereafter for the subsequent 3 years. Several methods have been developed to estimate conceptus dose from radiologic examinations. When the uterus is remote from the directly exposed tissues, the conceptus is exposed to scattered radiation and its dose is negligible (< 1 mGy). Examinations involving the abdomen-pelvis may deliver higher dose to the child. Variations in maternal body size and uterus position should be taken into account to obtain accurate conceptus dose estimation. Multidetector CT (MDCT) scanners have replaced conventional CT technology. Conceptus doses from abdominal MDCT range from about 13 to about 31 mGy during the first post-conception weeks for a scan acquired at 120 kVp, 200 mAs with a pitch of 1.0, depending on maternal body size and uterine position. Multi-phase abdominal CT examinations may deliver relatively high doses to the unborn child. Doses to the conceptus below 100 mGy should not be considered a reason for termination of pregnancy. The risk to the embryo/fetus for stochastic effects is assessed on the basis of dose using appropriate risk factors. Although these risks from a single diagnostic procedure are low for the majority of diagnostic x-ray examinations, it is important to ensure that doses are kept as low as reasonably achievable.