Editing Radioactive tracer (section)

==Applications==
{{See also|Nuclear medicine|List of PET radiotracers|Radionuclides associated with hydraulic fracturing}}
In [[metabolism]] research, tritium and [[carbon-14|<sup>14</sup>C]]-labeled glucose are commonly used in [[glucose clamp technique|glucose clamps]] to measure rates of [[glucose uptake]], [[fatty acid synthesis]], and other metabolic processes.<ref>{{cite journal | vauthors = Kraegen EW, Jenkins AB, Storlien LH, Chisholm DJ | title = Tracer studies of in vivo insulin action and glucose metabolism in individual peripheral tissues | journal = Hormone and Metabolic Research. Supplement Series | volume = 24 | pages = 41–8 | year = 1990 | pmid = 2272625 }}</ref>  While radioactive tracers are sometimes still used in human studies, [[stable isotope]] tracers such as [[carbon-13|<sup>13</sup>C]] are more commonly used in current human clamp studies. Radioactive tracers are also used to study [[lipoprotein]] metabolism in humans and experimental animals.<ref>{{cite journal | vauthors = Magkos F, Sidossis LS | title = Measuring very low density lipoprotein-triglyceride kinetics in man in vivo: how different the various methods really are | journal = Current Opinion in Clinical Nutrition and Metabolic Care | volume = 7 | issue = 5 | pages = 547–55 | date = September 2004 | pmid = 15295275 | doi = 10.1097/00075197-200409000-00007 | s2cid = 26085364 }}</ref>

In [[medicine]], tracers are applied in a number of tests, such as <sup>99m</sup>Tc in [[autoradiography]] and [[nuclear medicine]], including [[single-photon emission computed tomography]] (SPECT), positron emission tomography (PET) and [[Gamma camera|scintigraphy]]. The [[urea breath test]] for [[helicobacter pylori]] commonly used a dose of <sup>14</sup>C labeled urea to detect h. pylori infection. If the labeled urea was metabolized by h. pylori in the stomach, the patient's breath would contain labeled carbon dioxide. In recent years, the use of substances enriched in the non-radioactive isotope [[carbon-13|<sup>13</sup>C]] has become the preferred method, avoiding patient exposure to radioactivity.<ref>{{cite journal | vauthors = Peeters M | title = Urea breath test: a diagnostic tool in the management of Helicobacter pylori-related gastrointestinal diseases | journal = Acta Gastro-Enterologica Belgica | volume = 61 | issue = 3 | pages = 332–5 | year = 1998 | pmid = 9795467 }}</ref>

In [[hydraulic fracturing]], radioactive tracer isotopes are injected with hydraulic fracturing fluid to determine the injection profile and location of created fractures.<ref name="Reis_iodine" />  Tracers with different half-lives are used for each stage of hydraulic fracturing. In the United States amounts per injection of radionuclide are listed in the US [[Nuclear Regulatory Commission]] (NRC) guidelines.<ref name="NRC">{{cite web |url=https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1556/v14/#_1_26 |title=Consolidated Guidance About Materials Licenses: Program-Specific Guidance About Well Logging, Tracer, and Field Flood Study Licenses (NUREG-1556, Volume 14) |vauthors=Whitten JE, Courtemanche SR, Jones AR, Penrod RE, Fogl DB,((Division of Industrial and Medical Nuclear Safety, Office of Nuclear Material Safety and Safeguards)) |quote=labeled Frac Sand...Sc-46, Br-82, Ag-110m, Sb-124, Ir-192 |date=June 2000 |publisher=US Nuclear Regulatory Commission|access-date=19 April 2012}}</ref>  According to the NRC, some of the most commonly used tracers include [[antimony-124]], [[bromine-82]], [[iodine-125]], [[iodine-131]], [[iridium-192]], and [[scandium-46]].<ref name="NRC"/> A 2003 publication by the [[International Atomic Energy Agency]] confirms the frequent use of most of the tracers above, and says that [[manganese-56]], [[sodium-24]], [[technetium-99m]], [[silver-110m]], [[argon-41]], and [[xenon-133]] are also used extensively because they are easily identified and measured.<ref name="IAEA 2003">{{cite report |url=http://www-pub.iaea.org/MTCD/publications/PDF/Pub1171_web.pdf|title=Radiation Protection and the Management of Radioactive Waste in the Oil and Gas Industry |date=2003 |publisher=International Atomic Energy Agency |access-date=20 May 2012| pages = 39–40 |quote=Beta emitters, including <sup>3</sup>H and <sup>14</sup>C, may be used when it is feasible to use sampling techniques to detect the presence of the radiotracer, or when changes in activity concentration can be used as indicators of the properties of interest in the system. Gamma emitters, such as <sup>46</sup>Sc, <sup>140</sup>La, <sup>56</sup>Mn, <sup>24</sup>Na, <sup>124</sup>Sb, <sup>192</sup>Ir, <sup>99</sup>Tc<sup>m</sup>, <sup>131</sup>I, <sup>110</sup>Ag<sup>m</sup>, <sup>41</sup>Ar and <sup>133</sup>Xe are used extensively because of the ease with which they can be identified and measured. ... In order to aid the detection of any spillage of solutions of the 'soft' beta emitters, they are sometimes spiked with a short half-life gamma emitter such as <sup>82</sup>Br...}}</ref>