Radiopharmaceuticals
Updates to Article Attributes
Radiopharmaceuticals are drugs that are bound to radioactive substances. They may be used for diagnostic imaging, as therapeutic agents, or both (theranostic).
The most commonly used radionuclide is Technetium-99m. In some cases, such as Iodine-123, the radioactive molecule itself has a physiologic distribution that allows it to image the target organ. In others, the radioactive portion of the molecule is used primarily to tag and provide an imaging method for the pharmaceutically-active portion, which changes the biological distribution. One example of this is I-123 MIBG.
The particles emitted from diagnostic radiopharmaceuticals are detected either directly or indirectly by specialised equipment (e.g. SPECT, PET, gamma camera, etc.) to generate imaging. In other cases, the agent is used to have a tissue effect locally. For example, the alpha-emitter Ra-223 dichloride is used as a treatment for symptomatic osseous metastases and is not typically imaged.
The radioactivity of radiopharmaceuticals are commonly measured by using miliCurie (mCi) and megaBecquerel (MBq) where 1mCi is equivalent to 37MBq 1.
Properties of an ideal diagnostic radiopharmaceutical
short physical half life time
eliminated from the body with an effective half life time approximately equalling the examination time to prevent subsequent exposure to the body
pure gamma emitter by isomeric transition
gamma rays emitted should be monoenergetic (~150KeV)
high specific activity
localise largely and quickly at the target site
decay into a more stable daughter nucleus
easily and effectively attached to the chemical compound at room temperature
low cost per patient dose
can be easily produced or stored at the hospital site
-<p><strong>Radiopharmaceuticals</strong> are drugs that are bound to radioactive substances. They may be used for diagnostic imaging, as therapeutic agents, or both (<a href="/articles/theranostics" title="Theranostics">theranostic</a>).</p><p>In some cases, such as <a href="/articles/iodine-123" title="Iodine-123">Iodine-123</a>, the radioactive molecule itself has a physiologic distribution that allows it to image the target organ. In others, the radioactive portion of the molecule is used primarily to tag and provide an imaging method for the pharmaceutically-active portion, which changes the biological distribution. One example of this is <a href="/articles/mibg" title="MIBG">I-123 MIBG</a>.</p><p>The particles emitted from diagnostic radiopharmaceuticals are detected either directly or indirectly by specialised equipment (e.g. <a href="/articles/single-photon-emission-computed-tomography-spect" title="SPECT">SPECT</a>, <a href="/articles/positron-emission-tomography" title="PET">PET</a>, <a href="/articles/gamma-camera">gamma camera</a>, etc.) to generate imaging. In other cases, the agent is used to have a tissue effect locally. For example, the alpha-emitter <a href="/articles/radium-223-dichloride" title="Ra-223 dichloride">Ra-223 dichloride</a> is used as a treatment for symptomatic osseous metastases and is not typically imaged.</p><p>The radioactivity of radiopharmaceuticals are commonly measured by using miliCurie (mCi) and megaBecquerel (MBq) where 1mCi is equivalent to 37MBq <sup>1</sup>.</p><h4>Properties of an ideal diagnostic radiopharmaceutical</h4><ul>-<li><p>short <a href="/articles/half-life-time-1">physical half life time</a></p></li>-<li><p>eliminated from the body with an <a href="/articles/half-life-time-1">effective half life time</a> approximately equalling the examination time to prevent subsequent exposure to the body</p></li>-<li><p>pure <a href="/articles/gamma-decay" title="Gamma decay">gamma emitter</a> by <a href="/articles/isometric-transition">isomeric transition</a></p></li>-<li><p><a href="/articles/gamma-rays">gamma rays</a> emitted should be monoenergetic (~150KeV)</p></li>-<li><p>high <a href="/articles/specific-activity">specific activity</a></p></li>-<li><p>localise largely and quickly at the target site</p></li>-<li><p>decay into a more stable daughter nucleus</p></li>-<li><p>easily and effectively attached to the chemical compound at room temperature</p></li>-<li><p>low cost per patient dose</p></li>-<li><p>can be easily produced or stored at the hospital site</p></li>- +<p><strong>Radiopharmaceuticals</strong> are drugs that are bound to radioactive substances. They may be used for diagnostic imaging, as therapeutic agents, or both (<a href="/articles/theranostics" title="Theranostics">theranostic</a>).</p><p>The most commonly used radionuclide is Technetium-99m. In some cases, such as <a href="/articles/iodine-123" title="Iodine-123">Iodine-123</a>, the radioactive molecule itself has a physiologic distribution that allows it to image the target organ. In others, the radioactive portion of the molecule is used primarily to tag and provide an imaging method for the pharmaceutically-active portion, which changes the biological distribution. One example of this is <a href="/articles/mibg" title="MIBG">I-123 MIBG</a>.</p><p>The particles emitted from diagnostic radiopharmaceuticals are detected either directly or indirectly by specialised equipment (e.g. <a href="/articles/single-photon-emission-computed-tomography-spect" title="SPECT">SPECT</a>, <a href="/articles/positron-emission-tomography" title="PET">PET</a>, <a href="/articles/gamma-camera">gamma camera</a>, etc.) to generate imaging. In other cases, the agent is used to have a tissue effect locally. For example, the alpha-emitter <a href="/articles/radium-223-dichloride" title="Ra-223 dichloride">Ra-223 dichloride</a> is used as a treatment for symptomatic osseous metastases and is not typically imaged.</p><p>The radioactivity of radiopharmaceuticals are commonly measured by using miliCurie (mCi) and megaBecquerel (MBq) where 1mCi is equivalent to 37MBq <sup>1</sup>.</p><h4>Properties of an ideal diagnostic radiopharmaceutical</h4><ul>
- +<li><p>short <a href="/articles/half-life-time-1">physical half life time</a></p></li>
- +<li><p>eliminated from the body with an <a href="/articles/half-life-time-1">effective half life time</a> approximately equalling the examination time to prevent subsequent exposure to the body</p></li>
- +<li><p>pure <a href="/articles/gamma-decay" title="Gamma decay">gamma emitter</a> by <a href="/articles/isometric-transition">isomeric transition</a></p></li>
- +<li><p><a href="/articles/gamma-rays">gamma rays</a> emitted should be monoenergetic (~150KeV)</p></li>
- +<li><p>high <a href="/articles/specific-activity">specific activity</a></p></li>
- +<li><p>localise largely and quickly at the target site</p></li>
- +<li><p>decay into a more stable daughter nucleus</p></li>
- +<li><p>easily and effectively attached to the chemical compound at room temperature</p></li>
- +<li><p>low cost per patient dose</p></li>
- +<li><p>can be easily produced or stored at the hospital site</p></li>