Carbon-11: positron emission

Self-Test 17.2B Identify the nuclide produced and write the nuclear equation for (a) electron capture by iron-55 (b) positron emission by carbon-1 1. 

Almeida, P., Ribeiro, M. J., Bottlaender, M. et al. Absolute quantitation of iodine-123 epidepride kinetics using single-photon emission tomography comparison with carbon-11 epidepride and positron emission tomography. Eur. J. Nucl. Med. 26 1580-1588,1999. 

Gropler RJ, Geltman EM, Sampathkumaran K, Perez JE, Schechtman KB, Conversano A et al. Comparison of carbon-11-acetate with fluorine-18-fluorodeoxyglucose for delineating viable myocardium by positron emission tomography. J Am Coll Cardiol 1993 22 1587-1597... 

Rauch, S.L., Jenike, M.A., Alpert, N.M., Baer, L., Breiter, H.C., Savage, C.R., and Fischman, A.J. (1994) Regional cerebral blood flow measured during symptom provocation in obsessive-compulsive disorder using oxygen 15-labeled carbon dioxide and positron emission tomography. Arch Gen Psychiatry 51 62-70. 

Self-Test 17.3B Identify the nuclides that result from (a) electron capture by beryllium-7 and (b) positron emission from carbon-11. 

Carbon-11 is a radioactive source used in positron emission tomography (PET) scans. The equation for this process is ... 

A positron is a particle with the small mass of an electron but with a positive charge. A positron emission converts a proton into a neutron. Carbon-11 decays by positron emission ... 

Meyer, J. H., Houle, S., Sagrati, S., Carella, A., Hussey, D. F., Ginovart, N., Goulding, V., Kennedy, J., Wilson, A. A. 2004, Brain serotonin transporter binding potential measured with carbon 11-labeled DASB positron emission tomography effects of major depressive episodes and severity of dysfunctional attitudes, Arch.Gen.Psychiatry, vol. 61, no. 12, pp. 1271-1279. 

The correct answer is (B). The most obvious feature to note about the isotope shown is that the number of neutrons is less than the number of protons. The most likely decay, therefore, is one that will increase the number of neutrons and decrease the number of protons. In a positron emission, a proton is converted to a neutron and a positron. This has the effect of decreasing the atomic number by one while maintaining the same mass number. In this case, nitrogen—13 becomes carbon 13, which now has more neutrons than protons. 

Hume SP, Myers R, Bloomfield PM, Opacka-Juffry J, Cremer JE, Ahier RG, Luthra SK, Brooks DJ, Lammertsma AA (1992) Quantitation of carbon-11-labeled raclopridein rat striatum using positron emission... 

Yoshii, F., Kozuma, R., Takahashi, W., Haida, M., Takagi, S., Shinohara, Y. (1998). Magnetic resonance imaging and IIC-N-methylspiperone/positron emission tomography studies in patients with the interval form of carbon monoxide poisoning. J. Neurol. Sci. 160 87-91. 

In 2002, researchers at the Brookhaven National Laboratory in Upton, New York, examined brain samples from living baboons and mice that were administered toluene, a chemical found in many inhalants that is known to have abuse potential. By radiolabeling carbon atoms in toluene, the researchers mapped out the distribution of toluene in the brain and body using a technique called positron emission tomography (PET). 

The Stille coupling has also found a use in medicinal chemistry the incorporation of carbon-11 (half-life 20.3 min) to give products which are applicable in positron emission tomography has been described [182] aryl or vinyl residues can be transferred from tin in reactions with labeled methyl iodide which are complete in only 4 min ... 

Positron emission from carbon-11 decreases the number of protons from six to five, and increases the number of neutrons from five to six. 

Figure 25-9 shows the positron emission of a carbon-11 nucleus. Carbon-11 lies below the band of stability and has a low neutron-to-proton ratio of 0.8 1. Carbon-11 undergoes positron emission to form boron-11. Positron emission decreases the number of protons from six to five, and increases the number of neutrons from five to six. The resulting atom, has a neutron-to-proton ratio of 1.2 1, which is within the band of stability. 

C-Labelled phosgene is a useful material in radiopharmaceutical and nuclear medical applications, since it combines the radiophysical properties of C with the extensive reaction chemistry of phosgene to permit the rapid synthesis of a wide range of biologically-active materials with radiochemical labels. Carbon-11 is a short-lived positron-emitting radionucleide, useful for in vivo measurements with positron emission tomography (PET) [519], Because of... 

When an electron and its antiparticle, the positron, collide, they disintegrate and their matter is converted entirely into energy in the form of two gamma rays. In a positron emission, a proton in the nucleus is converted into a neutron and a positron. The neutron remains in the nucleus, and the positron is ejected. The life span of the positron is very brief since it will disintegrate upon collision with an electron. An example of a positron emission can be seen in the example showing the breakdown of carbon-11 ... 

To make the subscripts balance, the subscript for the missing nuclide must be 6, so the symbol for the product nuclide is C, for carbon. The mass number stays the same in positron emission, so we write 13. 

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