NORMALIZED ORGAN DOSE DATA MEASURED AS A FUNCTION OF FIELD SIZE FOR ABDOMINAL EXAMINATIONS

Doses to 14 radiosensitive organs were measured as a function of field size for both antero-posterior (AP) and postero-anterior (PA) project ions of the abdomen. The organ doses were measured using thermolumines cent dosemeters (TLD) placed within a Rando anthropomorphic phantom. C ircular field sizes 14 cm, 26 cm and 36 cm in diameter (measured at th e image intensifier input plane) were set for the PA irradiations. For the AP projections, the circular field sizes measured 14 cm, 20 cm, 2 7 cm and 40 cm in diameter, again specified at the input plane of the image intensifier. Organ doses were also measured for the conventional 35 x 35 cm film/screen technique, for both AP and PA views. The dose measurements were made at a tube potential of 81 kV, which is commonly used in radiological examinations of the abdomen. TLD were also used to measure the entrance surface dose (with backscatter) for each field size and projection. The organ doses are presented normalized to this entrance surface dose. A brief comparison is made between the data me asured in the current study and normalized organ dose data published b y other authors.