title: X-ray dose delivered during a longitudinal micro-CT study has no adverse effect on cardiac and pulmonary tissue in C57BL/6 mice.
abstract: BACKGROUND
  Micro-computed tomography (micro-CT) offers numerous advantages for small animal imaging, including the ability to monitor the same animals throughout a longitudinal study. However, concerns are often raised regarding the effects of X-ray dose accumulated over the course of the experiment.
  
  
  OBJECTIVE
  To scan C57BL/6 mice multiple times per week for 6 weeks, in order to determine the effect of the cumulative dose on pulmonary and cardiac tissue at the end of the study.
  
  
  METHODS
  C57BL/6 male mice were split into two groups (irradiated group = 10, control group = 10). The irradiated group was scanned (80 kVp/50 mA) three times weekly for 6 weeks, resulting in a weekly dose of 0.84 Gy, and a total study dose of 5.04 Gy. The control group was scanned on the final week. Scans from week 6 were reconstructed and the lungs and heart were analyzed.
  
  
  RESULTS
  Overall, there was no significant difference in lung volume or lung density or in left ventricular volume or ejection fraction between the control group and the irradiated group. Histological samples taken from excised lung and myocardial tissue also showed no evidence of inflammation or fibrosis in the irradiated group.
  
  
  CONCLUSIONS
  This study demonstrated that a 5 Gy X-ray dose accumulated over 6 weeks during a longitudinal micro-CT study had no significant effects on the pulmonary and myocardial tissue of C57BL/6 mice. As a result, the many advantages of micro-CT imaging, including rapid acquisition of high-resolution, isotropic images in free-breathing mice, can be taken advantage of in longitudinal studies without concern for negative dose-related effects.
authors: Imaging Research Laboratories, Robarts Research Institute, Western University, London, ON Department of Medical Biophysics, Western University, London, ON, Canada.
authors: Sarah A
authors: SA
authors: Detombe
authors: Imaging Research Laboratories, Robarts Research Institute, Western University, London, ON.
authors: Joy
authors: J
authors: Dunmore-Buyze
authors: Imaging Research Laboratories, Robarts Research Institute, Western University, London, ON.
authors: Ivailo E
authors: IE
authors: Petrov
authors: Imaging Research Laboratories, Robarts Research Institute, Western University, London, ON Department of Medical Biophysics, Western University, London, ON, Canada maria.drangova@imaging.robarts.ca.
authors: Maria
authors: M
authors: Drangova
mesh_terms: D000818:Animals; D055424:Cardiac-Gated Imaging Techniques; D006321:Heart / Q000000981:diagnostic imaging / Q000528:radiation effects*; D008137:Longitudinal Studies; D008168:Lung / Q000000981:diagnostic imaging / Q000528:radiation effects*; D008297:Male; D008810:Mice, Inbred C57BL; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D055425:Respiratory-Gated Imaging Techniques; D055114:X-Ray Microtomography / Q000379:methods*
keywords: Micro-CT; X-ray dose; cardiac function; lung density; lung volume; myocardial tissue; pulmonary tissue