The goal of this clinical trial study is to(1) determine the tissue specific dose of I-131 taken up by residing thyroid issue in the thyroid bed post-RAI along with any other sites in the neck and mediastinum as well as (2) correlate the dose delivered to residual tissues in the neck with patient follow-up based clinical outcomes, biochemical and imaging data following RAI therapy in patients with well-differentiated thyroid cancer (DTC). The main question[s] it aims to answer are:

• [question 1] How can obtained whole body and planar images more adequately depict residual iodine-avid disease in the thyroid bed, neck or mediastinum?
• [question 2] How can we obtain information on the dose taken up by the tumor remnant to know how much radionuclide actually went to the residual disease/tissue? Participants will [describe the main tasks participants will be asked to do, treatments they'll be given and use bullets if it is more than 2 items].

In our current clinical practice, patients with well-differentiated thyroid cancer (DTC) who receive oral administration of radioiodine 1-131 (RAI) have whole body and planar images obtained 4-5 days post-treatment. These images often do not adequately depict residual iodine-avid disease in the thyroid bed, neck or mediastinum. Further, no information about what dose taken up by the tumor remnant is obtained and thus we are unable to know how much radionuclide actually went to the residual disease/tissue.

Using single photon emission computed tomography (SPECT)/CT we will be able to better localize and evaluate disease/tissue remnant or distant iodine-avid metastatic disease. In addition, using Varian Velocity Theranostics Dosimetry suite of software applications, we will be able to do dosimetry on post-RAI therapy patients and be able to better correlate clinical outcomes with tumor absorbed dose in addition to provide quality improvement for the radioiodine ablation.

Inclusion Criteria:

• All minorities

• 18 years of age and older

• Ability to give consent

• Male or female

• Differentiated thyroid cancer (DTC)

• Previous total thyroidectomy

• Has either:

  • local lymph node metastases
  • distant mediastinal/cervical metastases
  • lung or osseous metastases as seen on prior imaging studies

Exclusion Criteria:

• Non-iodine avid disease
• Under 18 years of age
• Unable to give consent
• Pregnant women, Non-viable neonates or neonates of uncertain viability.
• Non-English-speaking patients

Thyroid Disease

De-identified data will be the only information available for sharing purposes.