Purpose: Because Micro‐CT utilizes ionizing radiation for image formation, radiation exposure during imaging is a concern. The objective of this study is to quantify the radiation exposure delivered during a Micro‐CT scan and to assess potential therapeutic effects associated with this radiation dose in a murine cancer model. Materials and Methods: Radiation exposure was measured using calibrated thermoluminescent dosimeters (TLD‐100) irradiated during a typical Micro‐CT scan protocol. TLD calibration curves were generated with a Cs‐137 irradiator. TLD's were implanted into a euthanized mouse and was imaged with Micro‐CT. TLD's were removed post‐scan and analyzed. Internal exposures were converted to dose in water. A C57BL/6 mouse lung tumor model derived by IV injection of 400,000 B16F10 murine melanoma cells was assessed for survivability and potential therapeutic effects due to absorbed radiation doses during Micro‐CT imaging. Results: A single Micro‐CT scan dose of 7.8±0.5 cGy was achieved when using a lucite anesthesia support module and a dose of 9.2±0.6 cGy with out the use of the anesthesia module. TLD data was validated using an ion chamber, providing measured radiation exposures of 8.1±0.4 cGy and 9.7±0.5 cGy with and with out the anesthesia module, respectively. Internal TLD analysis demonstrated an average mouse organ absorbed dose of 7.3±0.6 cGy. Conclusions: Survival analysis demonstrated a mean survival of nontreated control animals of 29±2 days, with animals receiving up to five sequential Micro‐CT studies surviving a mean of 30.5±1.5 days (total estimated dose of 39±2.5 cGy). The calculated cell survival fraction for a 9.2 cGy Micro‐CT scan was 99.25%. Therefore, negligible therapeutic effect from the radiation exposure delivered during Micro‐CT analysis was observed in the animal model investigated.
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging