Converting computed tomography images into photon interaction coefficients by using stoichiometric calibration and...

Area of Science:

• Medical Physics
• Radiological Imaging
• Radiation Dosimetry

Background:

• X-rays and gamma-rays are crucial in radiology, radiotherapy, and nuclear medicine.
• Accurate linear attenuation and energy absorption coefficients are vital for dose calculations and image correction.

Purpose of the Study:

• To develop a novel method combining stoichiometric calibration and parametric physical models.
• To convert computed tomography (CT) images into linear attenuation coefficients and linear energy absorption coefficients.

Main Methods:

• Performed calibration scans with tissue-equivalent materials to characterize X-ray energy spectrum.
• Established relationships between CT numbers and tissue parameters using literature data.
• Calculated linear attenuation and energy absorption coefficients via a parametric fit model.

Main Results:

• Demonstrated a linear correlation between CT numbers and tissue parameters.
• Identified potential errors in mass attenuation coefficient estimation at low photon energies (<50 keV) due to differences between tissue-equivalent materials and human tissues.
• Achieved validation errors of less than ±5% and ±8% for mass attenuation and mass energy transfer coefficients, respectively, compared to ICRU 46 report values.

Conclusions:

• The proposed method accurately evaluates photon interaction probabilities and tissue physical characteristics.
• The method has potential for diverse clinical applications in radiology and nuclear medicine.