[Gamma dose estimation to the gastric wall after administration of a capsule containing a large dose of 131I (author's transl)].
Gamma dose to the gastric wall from a capsule containing 1.85 GBq (50 mCi) of 131I was estimated in 6 patients who had received total thyroidectomy for thyroid carcinoma some years before. The tests were done with a 37 MBq (1 mCi) capsule each in 5 patiens and with a 185 MBq (5 mCi) capsule in one patient. All the patients were requested to fast in the morning. The capsule was given with a glass of water (200 ml). Then, the patient kept supine position under the scintillation camera for a period of one hour except one patient on whom the test was suspended at 30 minutes because of early clearance of the radioactivity from the stomach. In one of 5 patients who were tested for a period of one hour, serial scinticamera images showed almost no movement and minimum dissolution of the capsule. The remaining 4 patients showed slight to moderate movements of the capsules with a variety of dissolution  speeds. Data processings were done by Scintipac-1200. The estimated doses at the distance of 0.5 cm from the source were 3.820, 2.074, 1.445, 1.154 and 1.462 grays (382.0, 207.4, 144.5, 115.4 and 146.2 rads) per initial one hour and 375 mGy (37.5 rad) per initial 30 minutes, respectively. From these data, it is thought to be wise to advise the patient to rotate or shake the body on bed occasionally after swallowing the capsules containing a large dose of 131I for the treatment of thyroid cancer. It is also desirable to recommend the patient to walk around even though the controlled patient's room is small. Additional water may be also meaningful to avoid unnecessary irradiation to the gastric wall.
D000328:Adult; D000368:Aged; D002214:Capsules; D005260:Female; D005720:Gamma Rays; D006801:Humans; D007457:Iodine Radioisotopes / Q000008:administration & dosage* / Q000627:therapeutic use; D008875:Middle Aged; D011829:Radiation Dosage; D013270:Stomach / Q000528:radiation effects*; D013964:Thyroid Neoplasms / Q000532:radiotherapy
D002214:Capsules; D007457:Iodine Radioisotopes