Radiation dose calculation for Tc-99m HIDA in health and disease.

Radiation dose from Tc-99m HIDA has been calculated for normal subjects and for patients with various hepatobiliary diseases classified into four groups based on serum bilirubin level. The calculation was performed on biokinetic radioactivity data from blood, urine, liver, gallbladder, and intestines, using a biological approach that included a catenary model of the digestive organs. For normal subjects the critical organs were the gallbladder and the upper and lower large intestine, with doses of 910, 300, 200 mrad/mCi, respectively. The bone marrow, ovaries, and testes received 24, 62, and 4 mrad/mCi. For Group 4 patients with severe hepatobiliary disease (bilirubin greater than 10 mg/dl), the critical organs were the kidney, urinary bladder, and gallbladder, with doses of 130, 110, and 100 mrad/mCi. The bone marrow, ovaries, and testes received 9, 13, and 6 mrad/mCi. Thus the critical organs and overall radiation doses to organs change between health and disease.