Iodine-123
Last revised by Andrew Murphy ◉ on 3 Apr 2020
Citation, DOI, disclosures and article data
Citation:
Radswiki T, Murphy A, Bell D, et al. Iodine-123. Reference article, Radiopaedia.org (Accessed on 26 Sep 2023) https://doi.org/10.53347/rID-12706
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rID:
12706
Article created:
2 Jan 2011, The Radswiki ◉
Disclosures:
At the time the article was created The Radswiki had no recorded disclosures.
View The Radswiki's current disclosuresLast revised:
3 Apr 2020, Andrew Murphy ◉
Disclosures:
At the time the article was last revised Andrew Murphy had no recorded disclosures.
View Andrew Murphy's current disclosuresRevisions:
11 times, by 7 contributors - see full revision history and disclosures
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Synonyms:
- I-123
- Iodine-123 (I-123)
- I123
Iodine-123 (I123 or I-123) is a radioisotope of the element iodine (atomic number 53) used in nuclear medicine imaging including to scan the thyroid gland.
On this page:
Uses, dosages, and time of Imaging
- standard scan: 3.7-14.8 MBq (100-400 μCi) PO, image at 4-6 or 24 hours
- thyroid cancer scan: 55.5 MBq (1.5 mCi) PO, image at 4-6 or 24 hours
Physical properties
- photon energy: 159 keV
- physical half life: 13.2 hours
Normal distribution
- thyroid gland (target organ)
- nasopharynx
- salivary glands
- stomach (target organ)
- colon
- bladder (target organ)
- lactating breasts
Pharmacokinetics
Iodine-123 is rapidly absorbed from the gastrointestinal tract, with detectable activity in the thyroid gland within minutes. It reaches the thyroid follicular lumen in 20-30 min, with rapid trapping and organification.
Excretion
Excretion is primarily renal. It should be noted that it is also secreted in breast milk and crosses the placenta. As such it is contraindicated in pregnancy and requires precautions if breast feeding.
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