Iodine-131

Changed by Matt A. Morgan, 20 Jan 2016

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I131I-131
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I-131​ (or 131I) is a radioisotope used in the diagnosis and treatment of thyroid lesions. It is one of the oldest radiotracers used in nuclear medicine, spanningin use for over 50 years. It is predominately used in thyroid ablation therapy, for patients post thyroidectomy, and for metastatic thyroid cancer. 

131I-131​ is taken up by the thyroid cells and undergoes trapping and organification. It decays by

  • decay
    • beta emission (which damages the thyroid tissue) and
    • gamma emission (with a 364 keV photopeak used in imaging), with a
  • half life of approximately-life: approximately 8 days.

The high energy gamma emission leads to poor resolution images. However, the long half-life is beneficial for detecting occult metastatic disease because imaging can be done over a few days after oral administration of the radiopharmaceutical.

ItI-131 is predominately used in ablation therapy for patients post thyroidectomy for thyroid cancer. Generally, thea surgeon performs a near-total thyroidectomy (in order to preserve parathyroid function and due to the inherent difficulty in locating thyroid tissue deep within the neck). Therefore, an 131I  scan-131 scan is first performed after the patient has had surgery to look for and ablate functioning remnant thyroid tissue. 

  • -<p><sup>131</sup>I is a radioisotope used in the diagnosis and treatment of thyroid lesions. It is one of the oldest radiotracers used in nuclear medicine, spanning over 50 years. It is predominately used in ablation therapy for patients post thyroidectomy for thyroid cancer. </p><p><sup>131</sup>I is taken up by the thyroid cells and undergoes trapping and organification. It decays by beta emission (which damages the thyroid tissue) and gamma emission (with a 364 keV photopeak used in imaging), with a half life of approximately 8 days. The high energy gamma emission leads to poor resolution images. However, the long half-life is beneficial for detecting occult metastatic disease because imaging can be done over a few days after oral administration of the radiopharmaceutical.</p><p>It is predominately used in ablation therapy for patients post thyroidectomy for thyroid cancer. Generally, the surgeon performs a near-total thyroidectomy (in order to preserve parathyroid function and due to the inherent difficulty in locating thyroid tissue deep within the neck). Therefore, an <sup>131</sup>I  scan is first performed after the patient has had surgery to look for functioning remnant thyroid tissue. </p>
  • +<p><strong>I-131​</strong> (or <strong><sup>131</sup>I</strong>) is a radioisotope used in the diagnosis and treatment of <a title="thyroid" href="/articles/thyroid">thyroid</a> lesions. It is one of the oldest <a title="radiotracers" href="/articles/radiotracers">radiotracers</a> used in nuclear medicine, in use for over 50 years. It is predominately used in thyroid ablation therapy, for patients post thyroidectomy, and for metastatic thyroid cancer. </p><p>I-131​ is taken up by the thyroid cells and undergoes trapping and organification.</p><ul>
  • +<li>decay<ul>
  • +<li>
  • +<a title="beta emission" href="/articles/beta-emission">beta emission</a> (which damages the thyroid tissue)</li>
  • +<li>gamma emission (with a 364 keV photopeak used in imaging)</li>
  • +</ul>
  • +</li>
  • +<li>half-life: approximately 8 days</li>
  • +</ul><p>The high energy gamma emission leads to poor resolution images. However, the long half-life is beneficial for detecting occult metastatic disease because imaging can be done over a few days after oral administration of the radiopharmaceutical.</p><p>I-131 is predominately used in ablation therapy for patients post thyroidectomy for thyroid cancer. Generally, a surgeon performs a near-total thyroidectomy (in order to preserve parathyroid function and due to the inherent difficulty in locating thyroid tissue deep within the neck). Therefore, an I-131 scan is first performed after the patient has had surgery to look for and ablate functioning remnant thyroid tissue. </p>

References changed:

  • 1. Mettler FA, Guiberteau MJ. Essentials of Nuclear Medicine Imaging: Expert Consult - Online and Print, 6e. Saunders. ISBN:1455701041. <a href="http://books.google.com/books?vid=ISBN1455701041">Read it at Google Books</a> - <a href="http://www.amazon.com/gp/product/1455701041">Find it at Amazon</a><span class="auto"></span>

Tags changed:

  • radiopharmaceutical
  • nuclear medicine
  • radiotracer

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