Organ Dose Evaluations Based on Monte Carlo Simulation for CT Examinations Using Tube Current Modulation

Area of Science:

• Medical Physics
• Radiological Sciences
• Computational Imaging

Background:

• Accurate organ dose estimation is crucial for patient safety in computed tomography (CT).
• Tube current modulation (TCM) is a technique used to optimize radiation dose in CT examinations.
• Validation of simulation methods against experimental measurements is essential for reliable dose assessment.

Purpose of the Study:

• To estimate tube current values for X-ray projection angles in adult chest and abdomen-pelvis CT with TCM.
• To validate organ doses calculated using Monte Carlo (MC) simulations by comparing them with in-phantom dosimetry measurements.

Main Methods:

• Organ doses were simulated using MC software with CT scanner geometry, TCM curves, and phantom images.
• In-phantom dosimetry was performed using radio-photoluminescence glass dosemeters placed at organ positions.
• Simulated and measured organ doses were compared for chest and abdomen-pelvis CT scans.

Main Results:

• Relative differences between simulated and measured organ doses ranged from -2.5% to 11.0% for chest CT.
• Relative differences between simulated and measured organ doses ranged from -1.5% to 10.5% for abdomen-pelvis CT.
• The study demonstrated good agreement between MC-simulated and measured organ doses.

Conclusions:

• MC simulations with estimated TCM curves provide accurate organ dose estimations for adult CT.
• In-phantom dosimetry validates the reliability of MC simulations for CT dose assessment.
• These findings support the use of validated MC simulations for optimizing radiation protection in CT.