EFFECTIVE DOSE ESTIMATION FROM ORGAN DOSE MEASUREMENTS IN FAST-kV SWITCH DUAL ENERGY COMPUTED TOMOGRAPHY.

Area of Science:

• Medical Physics
• Radiological Dosimetry
• Computed Tomography

Background:

• Accurate estimation of effective dose (E) is critical for patient safety in computed tomography (CT).
• Dual-energy CT (DECT) offers advanced imaging capabilities but requires precise dose assessment.
• Metal-oxide-semiconductor field-effect transistor (MOSFET) detectors present a potential tool for in-vivo dosimetry.

Purpose of the Study:

• To validate a novel method for estimating effective dose (E) in fast-kV switch dual energy CT using MOSFET detectors.
• To characterize the effective energy of the DECT beam and calibrate MOSFET detectors accordingly.
• To experimentally compare dose measurements from MOSFET detectors against ion chambers.

Main Methods:

• Characterized the effective energy of the dual energy CT scanner.
• Calibrated MOSFET detectors to match the effective energy of the DECT beam.
• Validated calibration by comparing MOSFET and ion chamber (IC) dose measurements in a CTDI body phantom.
• Measured organ doses using an anthropomorphic phantom with 18 MOSFET detectors during a DECT abdomen/pelvis scan.
• Calculated effective dose (E) using ICRP 103 tissue weighting factors and partial volume correction.

Main Results:

• MOSFET and ion chamber measurements showed excellent agreement (17.1 mGy ± 3.8% vs. 17.1 mGy ± 0.4%).
• Effective dose (E) in the abdomen/pelvis DECT protocol was calculated as 17.8 mSv ± 11.6%.
• Comparison with the dose-length product method yielded a different effective dose estimate (14.62 mSv).

Conclusions:

• The novel MOSFET-based approach provides a validated method for estimating effective dose in dual energy CT.
• This technique offers potential for accurate organ dose and effective dose assessment in advanced CT protocols.
• Further investigation is warranted to reconcile discrepancies with the dose-length product method.