Advances in laboratory animal imaging have provided new resources for noninvasive biomedical research. Among these technologies is microcomputed tomography (microCT) which is widely used to obtain high resolution anatomic images of small animals. Because microCT utilizes ionizing radiation for image formation, radiation exposure during imaging is a concern. The objective of this study was to quantify the radiationdose delivered during a standard microCT scan. Radiationdose was measured using thermoluminescent dosimeters (TLDs), which were irradiated employing an x-ray source, with Al filtration and a total of for a full rotation of the unit. The TLD data were validated using a CT ion chamber probe. TLD results showed a single microCT scan air kerma of when using a poly(methylmethacrylate) (PMMA) anesthesia support module and an air kerma of without the use of the anesthesia module. The validation CT ion chamber study provided a measured radiation air kerma of and with and without the PMMA anesthesia module, respectively. Internal TLDanalysis demonstrated an average mouse organ radiation absorbed dose of . The author’s results have defined x-ray exposure for a routine microCT study which must be taken into consideration when performing serial molecular imaging studies involving the microCT imaging modality.
The authors wish to thank Dr. Michael J. Paulus from Siemens Pre-Clinical Solutions for providing information regarding the microCT unit and the x-ray source block, Mr. Richard Poelling from the Radiation Safety Office at the Harry S. Truman Memorial VA Hospital, Columbia, MO for providing the ion chambers employed in this investigation. They wish to acknowledge the contributions from the Environmental Health & Safety Office at the University of Missouri-Columbia for allowing them to use the Harshaw TLD reader, Dr. Tushar K. Ghosh from the Nuclear Science and Engineering Institute at the University of Missouri-Columbia for providing the ovens employed for TLD annealing, and Tammy L. Rold for her valuable assistance with animal handling and microCT scanning setup. This work was supported by American Cancer Society Grant No. RSG-99-331-04 CDD, DHHS-RO1-CA72942, DHHS 1 P50-CA130013, NIH-T32-RR07004, a VA Merit Award, and the VISN-15 HSTVA Research Award.
II. MATERIALS AND METHODS
II.A. Thermoluminescent dosimeters
II.B. TLD linearity and uncertainties
II.D. MicroCT system
II.E. MicroCT geometry
II.F. MicroCT radiation exposure
II.G. Mouse internal radiation absorbed dose measurements
III.B. MicroCT radiation exposure
III.C. Mouse internal radiation absorbed dose measurement
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