Many radioactive isotopes are used in medicine for imaging andtreatment purposes. The specific isotopes used depends on theparticular organ or body system being studied (for example, Xe-133is used to image lung function and blood flow.) For thyroidimaging, isotopes of iodine are used, commonly I-123 and I-131,which have half-lives of 13.2 hours and 8.0 days, respectively.
Why is iodine used for thyroid imaging (as opposed to any otherelement)?
I-129 is an extremely rare isotope of iodine with a half-life of15.7 million years. Assuming it was much more abundant in nature,would I-129 be a good substitute for I-123 or I-131 in thyroidimaging? Why or why not?
Although both I-123 and I-131 can be used in imaging of thethyroid, only I-131 is used in treating thyroid cancer. Whatdifference in radioactivity between I-123 and I-131 accounts forthis preference?
Sometimes non-radioactive isotopes of iodine can be preferreddepending on the intended medical use. For example, many peoplepreparing for a nuclear disaster stockpile KI tablets(non-radioactive). Why would someone consume KI during aradioactive disaster? Would you consider purchasing KI tablets as aprecaution? Why or why not?
