 While carrying out blood sampling, the operator will wear an electronic portable dosimeter EPD to measure radiation exposure. This device will be positioned on the operators chest to reflect the whole body dose received, and will be configured to record the radiation dose as a function of time during the procedure. After the procedure, the data from the EPD will be downloaded and split into two segments representing each blood sampling procedure, using the recorded timing information. Each segment will then be integrated to give the total radiation exposure received by the operator for each procedure. At the end of the treatment, patients will be asked which of the two blood sampling methods were the most tolerable. 