PATIENTS DOSE ESTIMATION IN CT EXAMINATIONS USING SIZE SPECIFIC DOSE ESTIMATES.

Area of Science:

• Medical Physics
• Radiology
• Diagnostic Imaging

Background:

• Computed Tomography (CT) is a vital diagnostic tool, but patient radiation exposure is a significant concern.
• Standard dose metrics like CTDIvol may not accurately reflect individual patient radiation doses due to variations in body size.
• Accurate dose assessment is crucial for optimizing patient safety in CT examinations.

Purpose of the Study:

• To evaluate and compare patient radiation exposure using Computed Tomography Dose Index (CTDI) and Size-Specific Dose Estimates (SSDE) methods.
• To assess radiation doses for head, chest, pelvis, and abdomen CT examinations on a 16-slice CT machine.
• To compare measured SSDE values with established benchmarks from the American Association of Physicist in Medicine (AAPM).

Main Methods:

• Radiation exposure was estimated using the Size-Specific Dose Estimates (SSDE) method.
• Patient dimensions were incorporated into phantom-measured CTDI values to calculate SSDE.
• Median CTDIvol and SSDE values were determined for head, chest, pelvis, and abdomen CT examinations.

Main Results:

• Median CTDIvol values were 26.76 mGy (head), 16.27 mGy (chest), 29.81 mGy (pelvis), and 14.74 mGy (abdomen).
• Median SSDE values were 54.1 mGy (head), 23.1 mGy (chest), 42.8 mGy (pelvis), and 20.1 mGy (abdomen).
• Measured SSDE values were 4-8% lower than AAPM reported values and showed significant variation compared to CTDI values.

Conclusions:

• CTDI parameters from the CT console are insufficient for specifying patient radiation dose.
• SSDE provides a more accurate patient-specific radiation dose estimation than CTDI.
• Accurate dose reporting in CT requires methods that account for individual patient characteristics.