Single dose planning for radioiodine-131 therapy of Graves' disease.
OBJECTIVE
Patients with Graves' disease were studied one year after radioiodine-131 therapy to assess the relationship between the effectiveness of the therapy and the radioiodine doses used.


METHODS
Patients were classified into three groups according to thyroid function as hyperthyroidism, euthyroidism and hypothyroidism at one year after I-131 therapy. In these groups we compared the mean values of dose, dose per thyroid weight calculated with I-123 uptake before the therapy (pre D/W), dose per thyroid weight calculated with therapeutic I-131 uptake (post D/W), and absorbed dose.


RESULTS
No significant differences were found between the three groups in terms of dose or pre D/W. The mean values of post D/W and absorbed dose in the non-hyperthyroid (euthyroid and hypothyroid) group were significantly greater than those in the hyperthyroid group. Post D/W of 6.3 MBq/g was a threshold separating the non-hyperthyroid group from the hyperthyroid group. There was no correlation between pre D/W and post D/W; however, the mean post D/W was significantly greater than the mean pre D/W. All patients with pre D/W above 6.3 MBq/g showed non-hyperthyroidism at one year after the radioiodine treatment.


CONCLUSIONS
No indicators before the radioiodine therapy had significant relationships with the effectiveness of the therapy at one year after the treatment. However, the single therapy planned for setting the pre D/W above 6.3 MBq/g will certainly make the patients non-hyperthyroid. As this proposal of dose planning is based on a small number of patients, further study is needed.
Kita
Tamotsu
T
Department of Biotracer Medicine, Kanazawa University Graduate School of Medical Sciences, Japan. happyman@nmd.m.kanazawa-u.ac.jp
Yokoyama
Kunihiko
K
Kinuya
Seigo
S
Taki
Junichi
J
Michigishi
Takatoshi
T
Tonami
Norihisa
N
D000328:Adult; D000368:Aged; D019583:Dose Fractionation, Radiation; D005260:Female; D006111:Graves Disease / Q000175:diagnosis* / Q000532:radiotherapy*; D006801:Humans; D007457:Iodine Radioisotopes / Q000008:administration & dosage*; D008297:Male; D011874:Radiometry / Q000379:methods*; D019275:Radiopharmaceuticals / Q000008:administration & dosage*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D011881:Radiotherapy, Computer-Assisted / Q000379:methods*; D016896:Treatment Outcome
D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals