Radiation Effects

Ionizing radiation is a recognized carcinogen.  X-rays are ionizing,  meaning they have the ability to interact with electrons, causing the atoms to  have an electrical charge.  The area of a cellular structure that is  interacted with can have a significant impact on a cells ability to function. If  the x-rays simply interact with water molecules within the cell, no damage may  be evident.  However, if the x-rays interact with protein molecules, DNA,  RNA, or enzymes, the cell can be greatly affected. When this happens, the cell  can either repair itself, survive in a damaged state, or die. So what can  happen?

  1. Instant cellular death - When a cell receives a massive dose of radiation, cellular disruption occurs rapidly.  DNA molecules break down and fatal chemical changes occur, leading to instant death.  Doses required to cause instant cellular death are much higher than those seen in medical x-ray imaging.  This kind of phenomenon would occur in nuclear accidents.
  2. Reproductive death - A cell can survive exposure to ionizing radiation and function as normal, but lose its ability to reproduce. 
  3. Genetic death - Some cells may be adversely effected, but still able to reproduce.  Usually cell division occurs only once or a few times and then the cell dies.
  4. Chromosomal breakage - In some cases, ionizing radiation can cause breaks in the DNA strand. The cell maintains its ability to reproduce, but may have permanent chromosomal abnormalities. This can lead to genetic mutations for future cellular generations.

Law of Bergonie and Tribondeau

Two scientists established a law which states the  radiosensitivity of cells is directly proportional to their reproductive  activity and inversely proportional to their degree of differentiation.  In  normal people speak, this means immature or rapidly dividing cells are much more  sensitive to radiation than mature cells or those that do not reproduce rapidly.   This is true for ALL types of cells.  Examples of various cells and tissues  and their radiosensitivity are: