Positron emission detection

Positron emission tomography (PET) is an imaging technique that relies on the emission of positrons from radionucleotides tagged to an injectable compound of interest. Each positron emitted by the radioisotope collides with an electron to emit two photons at 180° from each other. The photons are detected and the data processed so that the source of the photons can be identified and an image generated showing the anatomical localization of the compound of interest. 

Bastarrika G, Garcia-Velloso MJ, Lozano MD, et al. Early lung cancer detection using spiral computed tomography and positron emission tomography. Am J Respir Crit Care Med 2005 171(12) 1378-1383. 

A typical 19F NMR spectrum of a compound with a trifluorovinyl group is given in Fig. 6.20. This compound is the chemical precursor of the drug known as EF5, which is used in positron emission tomography imaging to detect hypoxic tissue. 

Positron emission tomography (PET) is another form of imaging that uses positron emitters, such as nC, 13N, 150 and 18F. These isotopes are incorporated into chemicals that are taken up by tissue. When the isotopes decay, the emitted positron reacts with a nearby electron, giving off 2 gamma rays, which are detected and an image of the tissue is created. 

Sawada SG, Allman KC, Muzik O, Beanlands RS, Wolfe ER, Jr., Gross M et al. Positron emission tomography detects evidence of viabiUty in rest technetium-99m sestamibi defects. J Am Coll Cardiol 1994 23 92-98... 

S.G. Stroobants, I. D Hoore, C. Dooms, P.R. De Leyn, P.J. Dupont, W.W. De, G. T. De, J.A. Verschakelen, L.A. Mortelmans, J.F. Vansteenkiste, Additional value of whole-body fluorodeoxyglucose positron emission tomography in the detection of distant metastases of non-small-cell lung cancer, Clin. Lung Cancer 4(4) (2003) 242-247. 

J. Leyton, J.R. Latigo, M. Perumal, H. Dhaliwal, Q. He, E.O. Aboagye, Early detection of tumor response to chemotherapy by 3 -deoxy-3 -[ F]fluorothymidine positron emission tomography The effect of cisplatin on a fibrosarcoma tumor model in vivo. Cancer Res. 65(10) (2005) 4202-4210. 

S. Hoegerle, C. Altehoefer, N. Ghanem, I. Brink, E. Moser, E. Nitzsche, F-DOPA positron emission tomography for tumor detection in patients with medullary thyroid carcinoma and elevated calcitonin levels, Eur. J. Nucl. Med. 28(1) (2001) 64-71. 

Another important characteristic is that ion beams can produce a variety of the secondary particles/photons such as secondary ions/atoms, electrons, positrons. X-rays, gamma rays, and so on, which enable us to use ion beams as analytical probes. Ion beam analyses are characterized by the respectively detected secondary species, such as secondary ion mass spectrometry (SIMS), sputtered neutral mass spectrometry (SNMS), electron spectroscopy, particle-induced X-ray emission (PIXE), nuclear reaction analyses (NRA), positron emission tomography (PET), and so on. 

Like the monoamine hypothesis of depression, such a simple hypothesis was appeaUng but, perhaps predictably, a Uttle too simple to be true. Further research using a technique known as positron emission tomography (PET) showed the relationship between dopamine and schizophrenia is more complex. PET detects radioactive emissions of certain isotopes these isotopes are incorporated into a molecule and injected into a patient. The machine measures the radioactivity with detectors positioned aroimd the body. PET lets researchers study the distribution of certain molecules in Uving tissue since, imUke autoradiography, the tissue is not sliced and treated chemically. The amoimt of radioactivity must be small, however, to avoid harming the human subjects. 

In positron emission tomography, positrons interact with electrons in body tissue to produce gamma rays that are detected and converted into an image. 

Sadzot, B., Mayberg, H.S., Frost, JJ. Detection and quantification of opiate receptors in man by positron emission tomography. Potential applications to the study of pain. Neurophysiol. Clin. 20(5), 323-334, 1990. 

Shinotoh, H., Iyo, M., Yamada, T., et al. Detection of benzodiazepine receptor occupancy in the human brain by positron emission tomography. Psvchophannacologv 99, 202 207, 1989. 

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