the distributions of radioactivity were monitored by recording pairs of anterior and posterior images of the abdomen using a gamma camera. Thepairs of images were recorded at approximately 20-minute intervals during the first 4 hours after dosing, then half-hourly to 10 hours and at 12 and 24 hours after doing. During the first 12 hours after dosing each image was of 50 sec duration and the 24-hour images were of 100 sec duration