RT Book, Section
A1 Hoel, David G.
A2 Klaassen, Curtis D.
A2 Watkins III, John B.
SR Print(0)
ID 1113951817
T1 Toxic Effects of Radiation and Radioactive Materials
T2 Casarett & Doull’s Essentials of Toxicology, 3e
YR 2015
FD 2015
PB McGraw-Hill Education
PP New York, NY
SN 9780071847087
LK accessbiomedicalscience.mhmedical.com/content.aspx?aid=1113951817
RD 2024/04/18
AB The  four  main  types  of  radiation  are  due  to  alpha  particles,  electrons  (negatively  charged  beta  particles  or  positively  charged  positrons),  gamma-rays,  and  X-rays.Alpha  particles  are  helium  nuclei  (consisting  of  two  protons  and  two  neutrons),  with  a  charge  of  +2,  that  are  ejected  from  the  nucleus  of  an  atom.Beta  particle  decay  occurs  when  a  neutron  in  the  nucleus  of  an  element  is  effectively  transformed  into  a  proton  and  an  electron,  which  is  ejected.Gamma-ray  emission  occurs  in  combination  with  alpha,  beta,  or  positron  emission  or  electron  capture.  Whenever  the  ejected  particle  does  not  utilize  all  the  available  energy  for  decay,  the  excess  energy  is  released  by  the  nucleus  as  photon  or  gamma-ray  emission  coincident  with  the  ejection  of  the  particle.The  Compton  Effect  occurs  when  a  photon  scatters  at  a  small  angle  from  its  original  path  with  reduced  energy  because  part  of  the  photon  energy  is  transferred  to  an  electron.Ionizing  radiation  loses  energy  when  passing  through  matter  by  producing  ion  pairs  (an  electron  and  a  positively  charged  atom  residue).Radiation  may  deposit  energy  directly  in  DNA  (direct  effect)  or  may  ionize  other  molecules  closely  associated  with  DNA,  hydrogen,  or  oxygen,  to  form  free  radicals  that  can  damage  DNA  (indirect  effect).