Multiple approaches for dosimetric characterization of a preclinical in vivo micro scanner: complementarity of...

The use of noninvasive imaging systems, such as microCT, is increasing for preclinical studies, especially to perform longitudinal studies. Although this imaging system offers advantages, it relies on the use of low-energy X-rays, and the dose absorbed by the tissues during acquisitions must be considered. This study aims to estimate the absorbed dose to soft tissue and bone during mouse microCT imaging, using experimental and numerical methods.

Experimental measurements estimated the tissue dose in euthanized mice or mouse phantoms during acquisitions with a microCT (90 kVp). Doses were assessed using radiochromic films, an ionization chamber and alanine pellets. Absorbed dose in bone tissues was assessed through EPR spectroscopy using bone samples taken from mice. Monte Carlo simulations were performed with GEANT4 to compare with experimental data and obtain the 3D dose distribution.

Experimental measurements for soft tissue dose estimation remain within acceptable limits, indicating satisfactory consistency between the different techniques of dosimetry (mean dose rate of 0.208Gy/min ± 7.4% at the center of the abdominal mouse region), consistent with the manufacturer's estimation (0.228Gy/min). Experimental and numerical methods also show good agreement for absorbed dose in bone, indicating that the dose in bone is approximately seven times higher than that to tissue (relative difference between experimental and simulation values of 2.50%).

The complementarity of experimental and numerical methods allowed for an accurate estimate of dose deposition in soft and bone tissues. MicroCT acquisition can lead to significant dose deposition in animal tissues and should not be neglected.