Correlation of size specific dose estimates with organ dose in abdominal spectral computed tomography.

BACKGROUND

In abdominal spectral Computed Tomography (CT), organ dose assessment is important for radiation safety but remains challenging due to the complexity of Monte Carlo (MC) simulations.

PURPOSE: This study aimed to compare the correlations of three size-specific dose estimate (SSDE) metrics (including the central slice SSDEcenter, the mean of all slices SSDEmean, and the organ-specific SSDEorgan) with organ doses and to establish a rapid estimation method for organ dose using linear regression in abdominal spectral CT.

METHODS

Monte Carlo N-Particle (MCNP6) was used to model the General Electric (GE) Revolution CT scanner, including its bowtie filter, radiation source, and simulations of tube voltage switching and the X-ray tube trajectory. Digital Imaging and Communications in Medicine (DICOM) data from 30 patients undergoing abdominal spectral CT with identical scan parameters were processed using 3D Slicer. Radiation-sensitive organs were delineated. Following this, digital models were constructed and subsequently voxelized. All patient external body contours were delineated using ImageJ software. Three SSDE metrics were calculated for all patients. Linear regression analysis was performed to correlate organ doses with the three SSDE metrics and to derive estimation coefficients.

RESULTS

The results indicated that in abdominal spectral CT examinations on a Revolution scanner, SSDEorgan exhibited the strongest correlation with organ dose. The R2 values for the liver, stomach, pancreas, spleen, kidneys, spinal cord, and bladder were 0.89, 0.61, 0.81, 0.85, 0.88, 0.94, and 0.68, respectively. The corresponding estimation coefficients derived from SSDEorgan for these organs were 0.42, 0.36, 0.37, 0.41, 0.36, 0.26, and 0.26, respectively. The estimation errors for the conversion coefficient combined with SSDEorgan, relative to the MC simulation results, were 7.34% for the liver, 6.09% for the kidneys, 13.25% for the spleen, 2.97% for the spinal cord, 13.61% for the pancreas, 17.64% for the stomach, and 18.56% for the bladder.

CONCLUSIONS

For abdominal spectral CT, SSDEorgan demonstrated the strongest correlation with individual organ doses. These findings enable rapid and accurate estimation of organ dose, providing a basis for personalized radiation dose assessment in clinical practice.