Radiation dose in repeated CT guided radiofrequency ablations.

OBJECTIVE: To calculate the cumulative effective and skin doses in patients that underwent repeated CT guided radiofrequency ablations (RFA). MATERIALS AND METHODS: From all patients that had undergone RFA during a five years period those which had three or more RFAs were selected. Using the CT images DICOM data, the dose length product (DLP), effective dose (E), skin dose profiles as well as the peak skin dose (PSD) were calculated, using appropriate methods and software developed for this purpose. For each patient, cumulative DLP and E were also calculated from the sum of the respective figures of each individual procedure. To calculate PSD, the skin dose profiles of each procedure were overlaid on the same Z-axis scale using anatomical landmarks for reference and the skin doses to each point were summed up. RESULTS: Five patients were studied; four had undergone 3 RFAs and one 10 RFAs. Cumulative DLP, E and PSD ranges were 5.6-22.3 Gy cm, 0.08-0.36 Sv and 0.8-3.4 Gy, respectively. Median E and PSD values per RFA were 35 mSv and 0.4 Gy, respectively. For comparison purposes it must be noted that in this CT department a routine abdomen-pelvis scan results to an E of about 10 mSv. CONCLUSIONS: Patients that undergo repeated RFAs are exposed to considerably high radiation exposure levels. When these patients are in the final stage of malignant diseases, stochastic effects may not be of major concern. However, optimization of the exposure factors and monitoring of these patients to avoid skin injuries are required.

Metastatic disease to the pancreas: an imaging challenge.

Metastatic lesions of the pancreas are uncommon, accounting for approximately 2% of pancreatic malignancies. Many tumours involve the pancreas secondarily and may manifest with different clinical and imaging characteristics. Although many patients have widespread disease, isolated metastases can be found. Surgical management is associated with improved survival in these cases. The experience of the pancreatic surgery unit and imaging department of our hospital in many patients presenting with pancreatic metastases is presented, and a review of the recent literature is undertaken. Main Messages • The early recognition of secondary pancreatic tumours on US, CT and MRI is extremely important. • Pancreatic metastases may mimic primary pancreatic adenocarcinoma or induce acute pancreatitis. • Most pancreatic metastases are discovered on a CT examination performed for follow-up.