الفهرس 
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Abstract
There is a worldwide concern about the use of ionizing radiation (IR) in the medical field. Occupational exposures in medical practice emerge from the implementation of processes in the most widespread use of X-ray diagnostic investigations and in nuclear medicine. The personnel involved are physicians, physicists, technologists, nurses and chemists representing the largest group of workers occupationally exposed to ionizing radiation from man-made sources. Two mechanisms induce biological impacts of ionizing radiation: direct damaging of DNA or indirect through generating free-radicals. The dominant approach during IR exposure to low-level doses (LLD) is the indirect one relying on the transfer of kinetic energy from electrons or photons to molecules.This transmission leads to water radiolysis and ROS formation. Multiple studies have shown that ROS is directly involved in oxidative damage to cellular macro-molecules, such as tissue lipids, proteins, and nucleic acids. This process is considered a cause of 70% of biological effects.(Jabeen et al. 2010, Masood et al. 2013).
In this study, our aim was to determine the effect of occupational exposure to low doses of ionizing radiation on serum immunoglobulin levels (IgG, IgA and IgM) and complement levels (C3 and C4) and main T-cell subsets (CD4+% and CD8+%) in hospitals radiation workers.
Individuals included to this study were divided into 2 main groups:
group I: 30 hospital radiation workers.
group II: 30 healthy volunteers’ age and sex matched as control group who had never worked in radiation-related jobs.
Our results showed that:
The mean values of serum concentration of immunoglobulins IgG, IgA and IgM in radiation workers were significantly higher than normal control group.The mean values of percentage and absolute count of CD4+ and CD8+ cells in radiation workers were significantly higher than normal control group.
The mean values of serum concentration of complement C3 and C4 were nearly in the same range in radiation workers and normal control subjects. Also there was nonsignificant difference between CD4/CD8 ratioin radiation workers and normal control subjects.
There were significant negative correlations between age and IgM, CD4+%, CD8+%, CD4/CD8 ratio and CD8+ absolute count. While nonsignificant correlations were present between the other studied parameters.There were significant negative correlations between working period and IgM, CD4+%, CD8+%, CD4/CD8 ratio and CD8+ absolute count. While nonsignificant correlations were present between the other studied parameters.