Просмотр кода страницы Английская Википедия:Fluorine-18

{{Английская Википедия/Панель перехода}}
{{Short description|Isotope of fluorine emitting a positron}}
{{Infobox isotope
 |image=Fluorine-18 decay.svg
 |image_caption=Decay over 24 hours
 |alternate_names =  Fluorine-18
 |mass_number =      18
 |symbol =           F
 |num_neutrons =     9
 |num_protons =      9
 |abundance =        [[Radioisotope]]
 |halflife =         {{val|109.771|(20)|ul=min}}
 |decay_mode1 =      [[Positron emission]] (97%)
 |decay_energy1 =    0.6335
 |decay_mode2 =      [[Electron capture]] (3%)
 |decay_energy2 =    1.6555
 |decay_product =    Oxygen-18
 |decay_symbol =     O
 |decay_mass =       18
 |mass =             18.0009380(6)
 |spin =             1<sup>+</sup>
 |excess_energy = {{val|873.431|0.593}}
 |binding_energy = {{val|137369.199|0.593}}
}}

'''Fluorine-18''' (<sup>18</sup>F) is a [[fluorine]] [[radioisotope]] which is an important source of [[positron]]s. It has a mass of 18.0009380(6) u and its [[half-life]] is 109.771(20) minutes. It decays by [[positron emission]] 96.7% of the time and [[electron capture]] 3.3% of the time. Both modes of decay yield stable [[oxygen-18]].

== Natural occurrence ==
{{chem|18|F}} is a natural [[trace radioisotope]] produced by [[cosmic ray spallation]] of atmospheric argon as well as by reaction of protons with natural oxygen: <sup>18</sup>O + p → <sup>18</sup>F + n.<ref name=SCOPE50>
[http://www.scopenvironment.org/downloadpubs/scope50 SCOPE 50 - Radioecology after Chernobyl] {{webarchive|url=https://web.archive.org/web/20140513065145/http://www.scopenvironment.org/downloadpubs/scope50/ |date=2014-05-13 }}, the [[Scientific Committee on Problems of the Environment]] (SCOPE), 1993. See table 1.9 in Section 1.4.5.2.</ref>

== Synthesis ==
In the [[radiopharmaceutical]] industry, fluorine-18 is made using either a [[cyclotron]] or [[linear particle accelerator]] to bombard a target, usually of natural or enriched [<sup>18</sup>O]water<ref>Fowler J. S. and Wolf A. P. (1982). The synthesis of carbon-11, fluorine-18 and nitrogen-13 labeled radiotracers for biomedical applications. Nucl. Sci. Ser. Natl Acad. Sci. Natl Res. Council Monogr. 1982.</ref> with high energy [[protons]] (typically ~18 [[MeV]]). The fluorine produced is in the form of a water solution of [<sup>18</sup>F][[fluoride]], which is then used in a rapid chemical synthesis of various radio pharmaceuticals. The organic oxygen-18 pharmaceutical molecule is not made before the production of the radiopharmaceutical, as high energy protons destroy such molecules ([[radiolysis]]). Radiopharmaceuticals using fluorine must therefore be synthesized after the fluorine-18 has been produced.

== History ==
First published synthesis and report of properties of fluorine-18 were in 1937 by Arthur H. Snell, produced by the nuclear reaction of <sup>20</sup>Ne(d,α)<sup>18</sup>F in the cyclotron laboratories of [[Ernest Lawrence|Ernest O. Lawrence]].<ref>{{Cite journal|last=Anonymous|date=1937-01-15|others=#5 shows the abstract of Arthur H. Snell about the discovery of the first produced fluorine-18.|title=Minutes of the Pasadena Meeting, December 18 and 19, 1936|url=https://link.aps.org/doi/10.1103/PhysRev.51.142|journal=Physical Review|language=en|volume=51|issue=2|pages=142–150|doi=10.1103/PhysRev.51.142|bibcode=1937PhRv...51..142. |issn=0031-899X}}</ref>

== Chemistry ==
Fluorine-18 is often substituted for a [[hydroxyl group]] {{no break|(–OH)}} in a radiotracer parent molecule, due to similar [[steric]] and [[electrostatic]] properties. This may however be problematic in certain applications due to possible changes in the molecule [[Chemical polarity|polarity]].

== Applications ==
Fluorine-18 is one of the early tracers used in [[positron emission tomography]] (PET), having been in use since the 1960s.<ref>{{cite journal|last1=Blau|first1=Monte|last2=Ganatra|first2=Ramanik|last3=Bender|first3=Merrill A.|title=18F-fluoride for bone imaging|journal=Seminars in Nuclear Medicine|date=January 1972|volume=2|issue=1|pages=31–37|doi=10.1016/S0001-2998(72)80005-9|pmid=5059349 }}</ref>
Its significance is due to both its short half-life and the emission of positrons when decaying. 
A major medical use of fluorine-18 is: in positron emission tomography (PET) to image the brain and heart; to image the thyroid gland; as a radiotracer to image bones and seeking cancers that have metastasized from other locations in the body and in radiation therapy treating internal tumors.

Tracers include [[sodium fluoride]] which can be useful for skeletal imaging as it displays high and rapid bone uptake accompanied by very rapid blood clearance, which results in a high bone-to-background ratio in a short time<ref>{{cite journal|last1=Ordonez|first1=A. A.|last2=DeMarco|first2=V. P.|last3=Klunk|first3=M. H.|last4=Pokkali|first4=S.|last5=Jain|first5=S.K.|title=Imaging Chronic Tuberculous Lesions Using Sodium [18F]Fluoride Positron Emission Tomography in Mice.|journal=Molecular Imaging and Biology|date=October 2015|volume=17|issue=5|pages=609–614|doi=10.1007/s11307-015-0836-6|pmid=25750032|pmc=4561601}}</ref> and
[[fluorodeoxyglucose]] (FDG), where the <sup>18</sup>F substitutes a [[hydroxyl]].
New dioxaborolane chemistry enables radioactive fluoride (<sup>18</sup>F) labeling of [[Antibody|antibodies]], which allows for [[positron emission tomography]] (PET) imaging of [[cancer]].<ref>{{Cite journal|last1=Rodriguez|first1=Erik A.|last2=Wang|first2=Ye|last3=Crisp|first3=Jessica L.|last4=Vera|first4=David R.|last5=Tsien|first5=Roger Y.|last6=Ting|first6=Richard|date=2016-04-27|title=New Dioxaborolane Chemistry Enables [18F]-Positron-Emitting, Fluorescent [18F]-Multimodality Biomolecule Generation from the Solid Phase|journal=Bioconjugate Chemistry|language=EN|volume=27|issue=5|pages=1390–1399|doi=10.1021/acs.bioconjchem.6b00164|pmc=4916912|pmid=27064381}}</ref> A <u>H</u>uman-<u>D</u>erived, <u>G</u>enetic, <u>P</u>ositron-emitting and <u>F</u>luorescent (HD-GPF) reporter system uses a human protein, [[Glutamate carboxypeptidase II|PSMA]] and non-immunogenic, and a small molecule that is positron-emitting (<sup>18</sup>F) and fluorescent for dual modality PET and fluorescence imaging of genome modified cells, e.g. [[cancer]], [[CRISPR/Cas9-mediated genome editing|CRISPR/Cas9]], or [[CAR-T cell|CAR T]]-cells, in an entire mouse.<ref>{{Cite journal|last1=Guo|first1=Hua|last2=Harikrishna|first2=Kommidi|last3=Vedvyas|first3=Yogindra|last4=McCloskey|first4=Jaclyn E|last5=Zhang|first5=Weiqi|last6=Chen|first6=Nandi|last7=Nurili|first7=Fuad|last8=Wu|first8=Amy P|last9=Sayman|first9=Haluk B.|date=2019-05-23|title=A fluorescent, [ 18 F]-positron-emitting agent for imaging PMSA allows genetic reporting in adoptively-transferred, genetically-modified cells|journal=ACS Chemical Biology|language=en|doi=10.1021/acschembio.9b00160|pmid=31120734|issn=1554-8929|pmc=6775626|volume=14|issue=7 |pages=1449–1459}}</ref> The dual-modality small molecule targeting [[Glutamate carboxypeptidase II|PSMA]] was tested in humans and found the location of primary and [[Metastasis|metastatic]] [[prostate cancer]], fluorescence-guided removal of cancer, and detects single cancer cells in tissue margins.<ref>{{Cite journal|last1=Aras|first1=Omer|last2=Demirdag|first2=Cetin|last3=Kommidi|first3=Harikrishna|last4=Guo|first4=Hua|last5=Pavlova|first5=Ina|last6=Aygun|first6=Aslan|last7=Karayel|first7=Emre|last8=Pehlivanoglu|first8=Hüseyin|last9=Yeyin|first9=Nami|last10=Kyprianou|first10=Natasha|last11=Chen|first11=Nandi|date=March 2021|title=Small Molecule, Multimodal [18F]-PET and Fluorescence Imaging Agent Targeting Prostate Specific Membrane Antigen: First-in-Human Study|journal=Clinical Genitourinary Cancer|volume=19 |issue=5 |language=en|pages=405–416| pmid=33879400 | doi=10.1016/j.clgc.2021.03.011| pmc=8449790|doi-access=free}}</ref>

== References ==
{{Reflist}}

{{Isotope sequence
|element=fluorine
|lighter=[[fluorine-17]]
|heavier=[[fluorine-19]]
|before=[[neon-18]]
|after=[[oxygen-18]]
}}

[[Category:Isotopes of fluorine]]
[[Category:Medicinal radiochemistry]]
[[Category:Positron emitters]]
[[Category:Medical isotopes]]
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