Accelerators radiation safety

As for the accelerated ion beams, contrary to PIXE and RBS, in NRA the use of deuterons is favored because of the high yields produced with them. However, the deuteron beam itself can produce more neutrons than any other ion beams therefore, its use is associated with the possibility of neutron hazard. NRA requires only very small deuteron beam intensities, the orders of 100 pA-10 nA, contrary to basic nuclear physics, where pA beams are common. Moreover, the energy of the deuteron beam used for analysis is quite low (usually lower than 2 MeV), thus practically no health hazard is expected around the experimental facility (Kiss et al. 1994). Nevertheless, radiation safety rules demand heavy shielding against neutrons for laboratories working with deuteron beams, which is not available around many accelerators. This is a limiting factor for the wide use of deuteron-induced NRA. 

Improvements in the physical selectivity, from orthovoltage x-ray to cobalt-60 and high-energy linear accelerators, combined with more powerful diagnostic tools and radiation delivery methods have continuously improved the results of photon therapy (3-D or inverse planning, conformal- and intensity-modulated radiation therapy, and stereotactic methods). The safety and the reliability of photon therapy are well established. 

Similarly, carbon-14-labeled compounds have no equal for assessment of their metabo-hsm in vitro (such as with hepatocytes, cytochrome P450 subtypes or other enzyme or subceUular tissue preparations), or for in vivo characterization of their absorption, distribution, metabolism and excretion (ADME) in animals and humans, as they can be detected by several different methods and accurately quantified in complex biological matrices. One of the newer of these methods is accelerator mass spectrometry (AMS)", whose exquisite sensitivity allows the use of far smaller quantities of carbon-14 than standard ADME studies, therefore providing increased safety margins with regard to radiation exposure to human volunteers. 

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