Experimental studies on injury effects of repeated computed tomography scan in mice / 中华放射医学与防护杂志

ABSTRACT

Objective To investigate the effects of repeated computed tomography (CT) scan on hematological and immunological index in mice,and to explore the related mechanism.Methods A total of 60 BALB/c mice were randomly divided into six groups as control,once,twice,4,6 and 8 times of CT scans,and administered with whole-body scan by 64-slice spiral CT with the pelvis scan mode.Thermoluminescence dosimeter was used to detect the absorbed doses of CT scan,while DNA damage (γ-H2AX),apoptosis,autophagy,cell cycle and percentages of CD4/CD8 in peripheral lymphocytes and bone marrow cells were analyzed by flow cytometry.γ-H2AX was detected 1 h after the last CT scan,and the other indexes were detected 24 h after the last CT scan.Results γ-H2AX increased after more than twice CT scans in peripheral lymphocytes and after than 4 times of CT scan in bone marrow cells (P ＜ 0.05).Apoptosis increased in peripheral blood lymphocytes and decreased in bone marrow cells after more than 4 times of CT scan (P ＜ 0.05),suggesting that lymphocytes were more sensitive while different cell subpopulation in bone marrow showed different sensitivity and response phase.No obvious changes of autophagy level were observed in peripheral blood lymphocytes,while autophagy increased in bone marrow cells after single CT scan (F =81.10,P ＜ 0.05).8 times of CT scan significantly increased the percentages of cells at G0/G1 phase and G2/M phase(x2 =11.29,28.57,P ＜0.05).The percentage of CD4 + T,CD8 + T cells decreased after CT scan,but no effects on the ratio of CD4 +/CD8 +.Conclusions Repeated CT scans could induce injury effects on hematopoietic system and immune system,and then the apoptosis.Apoptosis,autophagy and cell cycle arrest might be initiated to maintain genome stability but there is no influence on immune balance.