320. Radioiodine kinetic in small pool hyperthyroid patients. (December 2018)

• Record Type: Journal Article
• Authors: Canzi, C.; D'Alessio, A.; Longari, V.; Buffoni, F.; Martina, I.; Roveretti, D.; Benti, R.
• Is Part Of: Physica medica. Volume 56(2018)Supplement 2
• Page Start: 257
• Publication Date: 2018-12
• Subjects: Medical physics -- Periodicals; Biophysics -- Periodicals; Biophysics -- Periodicals; Imagerie médicale -- Périodiques; Radiothérapie -- Périodiques; Rayons X -- Sécurité -- Mesures -- Périodiques; Physique -- Périodiques; Médecine -- Périodiques; 610.153
• DOI: 10.1016/j.ejmp.2018.04.329
• Languages: English
• ISSNs: 1120-1797

Abstract

Abstract : Purpose: Small pool (SP) hyperthyroid patients have a high intrathyroidal radioiodine turnover with a rapid excretion of iodine bound to proteins that circulate into blood and accumulate into liver. The aim of this work was to study the radioiodine kinetic in thyroid, blood, WB and liver in SP patients in comparison to non small pool (NSP) patients and to evaluate contributions of blood self-irradiation and penetrating radiation from WB to mean absorbed dose to blood ( D blood / A 0 ) and the dose to the liver. Methods: After pre-therapy dosimetry 10 hyperthyroid patients were classified as SP. After therapeutic administration, blood samples were taken since 0.1 h to 168 h and thyroid and WB images were acquired at 2, 5, 24, 48, 96, 168 h to study iodine kinetic in blood, thyroid, WB and liver. The same study was performed on 4 NSP patients. Results: Thyroid: in SP patients mean uptake at 5 h was higher than at 24 h: 73 ± 6% vs 60 ± 12%; in NSP it was the contrary: 31 ± 12% vs 46 ± 10%. Blood: up to 5 h there was no difference between SP and NSP patients. After 24 h NSP patients presented a continuous decrease of 131 I concentration, while in SP ones there was a high increase, in correspondence of thyroid dismission, with slow clearance. Contribution of blood self-irradiation to D blood / A 0 was 0.46 ± 0.20 Gy/GBq and 0.09 ± 0.06 Gy/GBq for SP and NSP patients (p = 0.004) respectively. WB: there was no difference between SP and NSP patients. Contribution of penetrating radiation from WB to D blood / A 0 was 0.19 ± 0.05 Gy/GBq and 0.16 ± 0.03 Gy/GBq for SP and NSP patients (p = 0.23) respectively. Liver: in NSP patients liver was never visible, in SP patients it was since 24 h. Liver mean dose was 953 ± 721 mGy/GBq. Conclusions: Radioiodine kinetic in SP hyperthyroid patients is different from NSP ones: in thyroid, uptake is higher at 5 h than at 24 h; in blood, after an initial fast clearance, there is an increment of concentration at 24 h; in WB scans liver is visible since 24 h and so it is self-irradiated by radioiodine; contribution of blood self-irradiation to D blood / A 0 is higher than that from penetrating radiation from WB.