Patient dose measurements from femoral angiography

Investigation of patient dose from femoral angiography requires detailed logging of dose-area product (DAP) measurements, which is time-consuming and only possible on small numbers of patients. A simple model for the femoral angiogram study consists of two regions; lower limbs and torso. The experimental phantom was the abdominal and pelvic sections of a Rando phantom, and two 10 cm diameter water filled cylinders to represent a lower limb. DAP rate during screening, and the DAP per spot film exposure were obtained in two rooms. Total DAP values were measured on 100 patients in each room. The median screening time and number of spot film exposures were divided between the two regions. The DAP from screening and spot films for each region was estimated by combining the phantom and patient data. The total DAP predicted by the model agreed to within 7% of the median DAP from the patient studies. Conversion to effective dose gave 9.0 mSv for the newer room compared with 2.8 mSv for the older room. In the newer room it was estimated that digital spot film exposure contributed 88% of the total effective dose. In the same room, exposure of the torso contributed 98% of the total effective dose. The model will enable interpretation of total DAP measurements made from femoral angiogram studies without the need for detailed DAP measurements on every patient. Attempts to reduce patient dose from femoral angiography must concentrate on reduction of the number and dose per exposure from abdominal and pelvic digital spot films.