Question

List what factors determine how dangerous a source of radiation is

Answer 1

Answer :

The following Factors determine how dangerous a source of radiation is :

Physical factors :

Physical factors include the type of radiation use : High LET radiation will usually have a greater biological effect. This is due to increased cell killing as radiation induced damage is more closely spaced. As LET increases over 100 keV/μm, cell killing decreases as the energy delivered exceeds that needed to kill the cell.
The rate at which dose is delivered will also impact on cell survival, as low dose rates allow for DNA repair to occur during radiation delivery. Very low dose rates may also allow reoxygenation or redistribution to occur.

The total dose : its the most important physical factor. Very low doses are unlikely to lead to any visible response, whereas very high doses (single dose over 20 Gy) have the potential to kill most human cells.  

and The temperature of the treated volume : Increased temperature leads to an increase in cell killing.

Biological factors :

Biological factors are due to the cell being irradiated or the organism as a whole. Different organisms have different tolerances to radiation. Most eukaryotic cell cultures demonstrate significant cellular death at doses of 1 – 2 Gy. Bacteria are relatively radioresistant, requiring doses far above those in mammalian cells before significant cell death occurs.

The different cells within an organism may also show differing radiosensitivity. Haemopoietic cells typically respond to low doses of radiation, whereas well differentiated skin cells do not suffer ill consequences except at very high doses.