I don’t believe we are allowed to post links, but try an internet search for "low iodine" and "thyroid cancer".
Thyroid cancer survivors use a low-iodine diet prior to getting periodic scans, so there is a cancer support group that offers low-iodine tips as well as a free cookbook in PDF format that you can download.
I have actually heard different stories as to whether the low-iodine diet is necessary prior to a scan, but my endo had me follow one for 2 weeks. The free cookbook was a huge help…I also bought an additional one from Amazon that I found by searching for "low iodine".
Best of luck!
Kimberly