The influence of x-ray contrast agents in computed tomography on the induction of dicentrics and gamma-H2AX foci in lymphocytes of human blood samples.
The aim of this study was to investigate and quantify two biomarkers for radiation exposure (dicentrics and gamma-H2AX foci) in human lymphocytes after CT scans in the presence of an iodinated contrast agent. Blood samples from a healthy donor were exposed to CT scans in the absence or presence of iotrolan 300 at iodine concentrations of 5 or 50 mg ml(-1) blood. The samples were exposed to 0.025, 0.05, 0.1 and 1 Gy in a tissue equivalent body phantom. Chromosome aberration scoring and automated microscopic analysis of gamma-H2AX foci were performed in parts of the same samples. The theoretical physical dose enhancement factor (DEF) was calculated on the basis of the mass energy-absorption coefficients of iodine and blood and the photon energy spectrum of the CT tube. No significant differences in the yields of dicentrics and gamma-H2AX foci were observed in the absence or presence of 5 mg iodine ml(-1) blood up to 0.1 Gy, whereas at 1 Gy the yields were elevated for both biomarkers. At an iodine concentration of 50 mg ml(-1) serving as a positive control, a biological DEF of 9.5 +/- 1.4 and 2.3 +/- 0.5 was determined for dicentrics and gamma-H2AX foci, respectively. A physical DEF of 1.56 and 6.30 was calculated for 5 and 50 mg iodine ml(-1), respectively. Thus, it can be concluded that in the diagnostic dose range (radiation and contrast dose), no relevant biological dose-enhancing effect could be detected, whereas a clear biological dose-enhancing effect could be found for a contrast dose well outside the diagnostic CT range for the complete radiation dose range with both methods.
Bayer Schering Pharma AG, 13353 Berlin, Germany.
G
G
Jost
S
S
Golfier
H
H
Pietsch
P
P
Lengsfeld
M
M
Voth
T E
TE
Schmid
F
F
Eckardt-Schupp
E
E
Schmid
D015415:Biomarkers / Q000378:metabolism; D001769:Blood / Q000187:drug effects / Q000528:radiation effects; D002869:Chromosome Aberrations; D003287:Contrast Media / Q000494:pharmacology*; D004307:Dose-Response Relationship, Radiation; D006657:Histones / Q000378:metabolism*; D006801:Humans; D007455:Iodine; D008214:Lymphocytes / Q000528:radiation effects*; D015233:Models, Statistical; D019047:Phantoms, Imaging; D011874:Radiometry / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014965:X-Rays
D015415:Biomarkers; D003287:Contrast Media; C468783:H2AX protein, human; D006657:Histones; D007455:Iodine