Gamma/ x ray radiation is an electromagnetic wave or photon and has no electrical charge
Gamma/ x ray radiation can ionize as a result of direct interactions with orbital electrons and is transmitted directly to its target. Because Gamma/ x ray radiation have no charge and no mass, it has a very high penetrating power.
Neutron radiation consists of neutrons that are ejected from the nucleus and have no electrical charge
Due to their neutral charge, neutrons interact with matter either directly or indirectly
Because of the lack of a charge, neutrons have a relatively high penetrating ability and are difficult to stop.
The reactions caused by ionizing radiation occur rapidly, they are nonselective and random.
The majority of damage caused by radiation is due to chemical reactions with water within the cell.
H 2 O HOH + e - water electron Positively charged water molecule Radiation reacts with water to produce an electron and a positively charged water molecule.
H 2 O HOH + e - + H 2 O HOH - water negatively charged water molecule electron water Positively charged water molecule The electron reacts with another water molecule to produce a negatively charged water molecule
H 2 O HOH + H + OH * e - + H 2 O HOH - water negatively charged water molecule Hydrogen ion Hydroxyl radical electron water Positively charged water molecule The positively charged water molecule dissociates into a hydrogen ion and a hydroxyl radical.
H 2 O HOH + H + OH * H * OH - e - + H 2 O HOH - water negatively charged water molecule Hydrogen ion Hydroxyl radical electron water Positively charged water molecule hydrogen radical Hydroxyl ion The negatively charged water molecule dissociates into a hydrogen radical and a hydroxyl ion.
The arrangement of nitrogenous bases provide a blueprint for DNA for the synthesis of specific proteins necessary for individual cell function.
In the event of a loss or change of one or more of the nitrogenous bases, base sequence and normal functioning of the cell is altered.
Another form of DNA damage due to radiation involves a break in the hydrogen bonds between the Adenine – Thymine and Cytosine – Guanine base pairs. These bonds function to keep the DNA strands together
Bonds can also break between deoxyribose sugar and the phosphate groups which can lead to cross-linking of DNA
Leaver, D., Washington C.M. (2004) Principals and Practice of Radiation Therapy. Second Edition pp. 55-84 St Louis, Mosby
Statkiewicz Sherer, M.A., Ritenour, E.R., Visconti, P.J. (2002) Radiation Protection in Medical Radiography. Fourth Edition, pp85-154, St. Louis, Mosby.
Ott, M.E. (2006, April 12) Radiation and why it is bad for humans. A videotaped lecture describing Radiation Types, Effects & Sources http://video.google.com/videoplay?docid=-1764500297917980309&q=radiation
Gwozdz, J. T. (2002, July 20). IMRT - Intensity Modulated Radiation Therapy. A powerpoint presentation of IMRT Intensity Modulated Radiation Therapy. http://drjohng.com/Talk/IMRT/Slide1_GIF.html