الفهرس 
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Abstract
Humans are naturally exposed to ionizing radiation from cosmic rays, and artificially through diagnostic procedures, medical treatments or occupationally during work shifts. It is well known that ionizing radiation produces DNA damage through different mechanisms: by loss of bases, single-strand breaks, double strand breaks, and damage to purine and pyrimidine bases. It is considered that no dose of ionizing radiation exposure is safe. However, once the accurate absorbed dose is estimated, one can be given appropriate medical care and the severe consequences can be minimized.
Among the key cellular components that are sensitive to IR are lymphocytes which DROP sharply after exposure to the different doses of irradiation. This reduction may be due to irradiation damage of lymphocyte DNA since there is no lethal damage to red blood cells (RBCs) because they lack nuclei. However, other damages to erythrocytes may influence the quality of RBC concentrates. However, they did not observe damage to the hemoglobin structure, as assessed by the degree of hemoglobin denaturation.
Methemoglobin is a form of haemoglobin, which contains the ferric ion. In the normal physiological state, methemoglobin is formed by auto-oxygenating the heme iron of oxygenated haemoglobin. The rate of auto-oxygenation is about 3 % per day. Free radicals generated by ionizing radiation in an organism may take one electron from the ferrous ion of oxygenated haemoglobin to form methemoglobin. Methemoglobin cannot bind oxygen, unlike oxyhemoglobin. In human blood, a trace amount of methemoglobin is normally produced spontaneously. A higher percentage than this can be genetic or caused by exposure to various chemicals and ionizing radiation. In this study, we used methemoglobin to estimate the absorbed dose to radiation workers.
The aim of this study was to determine the impact of occupational exposure to low dose ionizing radiation on red blood cells hemoglobin.
This study included 100 subjects divided into four main groups:
group I: High dose exposure group: 25 breast cancer patients were treated with post-operative radiotherapy.
group II: Low dose exposure group: 25 hospital radiation workers.
group III: 25 female healthy volunteers’ age and sex matched as control group for breast cancer patients who had never worked in radiation-related jobs.
group VI: 25 healthy volunteers’ age and sex matched as control group fpr radiation workers who had never worked in radiation-related jobs
Our results showed that:
• A significant decrease in WBCs and MCV was observed among radiation workers in comparison to control group while there was insignificant difference in mean values of Hb, RBCs, Ht, RDW and M.C.H.
• Methemoglobin levels and Reticulocyte % were significantly higher in radiation workers when compared to control group.
• Serum ferritin levels were significantly lower in radiation workers than those in control group while insignificant difference was found in serum iron levels among radiation workers when compared to their corresponding controls.
• Mean values of WBCs, HB and RBCs were significantly lower in BCPs after radiotherapy treatment when compared to radiation workers while there was insignificant difference in mean values of Ht, MCV, MCH and RDW.
• Serum methemoglobin and Reticulocyte % were significantly higher in radiation workers in comparison to BCPs after radiotherapy.
• A significant decrease in serum levels of ferritin in radiation workers when compared to BCPs after radiotherapy while insignificant difference was found in serum iron levels.