I don't understand why my doctor is telling me to get radioactive therapy

[Kim87]

Hello, everyone I've been gone for a while dealing with college but now ,once again I'm dealing with more thyroid problems. I'm sorry that this is so long. Here is a little update, a few months ago my endo sent me to have an  a thyroid scan/uptake because my ultrasound showed that I had several cystic subcentimeter nodules. The results from the uptake scan showed no hot or cold nodules but my uptake percentages were slightly high and the nodules that were present in my ultrasound were too small to be seen during the scan. BTW- ALL OF MY BLOODWORK IS NORMAL. My endo started me on  50 mcg(0.05 mg) of  Synthroid to take once a day to try and shrink my cystic nodules because they are really bothering me. After being on the synthroid for two months, she told me to stop taking it because it's not working, she said nothing has changed and therefore in 6 weeks she wants me to get radioactive therapy to shrink my cystic nodules. She also had me do another ultrasound here are the results:

The right lobe of the thyroid gland measures 4.5x 1.4x 2.4 cm and has a heterogenous echotexture. There are multiple cystic nodules seen in the middle and lower portions of the right thyroid gland containing inspissated colloid material, the largest of these measures 4mm. The isthmus measures 3mm in thickness. The left lobeof the thyroid gland measures 4.1x1.2x2.0 cm and contains multiple cystic nodules, which a group of cystic nodules are seen aggregated in the lower portion of the left lobe. The largest discrete nodule measures 5mm. Some of these nodules appear to contain inspissated colloid material. No dominant nodule is identified. There is no cervial lymphadenopathy.

Impression: No dominant single nodule is seen. There are several cystic subcentimeter nodules seen in both lobes of the thyroid gland as described above.

I'm so confused now, is radioactive thearpy REALLY MY ONLY OPTION and what does my ultrasound results mean? She also ordered more blood results that include thyroid stimulating immunoglob, T-3 FREE, Hemoglobin A1C, thyroid cascade profile, CBC  w/DIFF, COMP METABOLIC ,T-4 ,and TSH. I've already had some of these tests a few months ago.

Thanks so much,

Frances