Calculation method for novel upright CT scanner isodose curves

Area of Science:

• Medical Physics
• Computational Dosimetry
• Radiation Protection

Background:

• New upright and tilting CT scanners require accurate radiation protection assessments.
• Traditional methods for radiation shielding rely on dose distribution estimations.

Purpose of the Study:

• To develop and apply a Monte Carlo computational method for calculating isodose curves.
• To assess radiation protection requirements for a novel upright and tilting CT scanner.

Main Methods:

• Utilized the TOPAS code platform with imported CAD files to model the scanner.
• Simulated a water phantom to represent patient scatter.
• Calculated maximum intensity dose maps across various tilt angles.

Main Results:

• Isodose lines were more rounded and closer to isotropic compared to single-tilt angle calculations.
• Results align with isotropic scatter assumptions used in CTDI and DLP-based radiation protection.
• Dose distribution showed less dose above the isocenter due to increased shielding material.

Conclusions:

• The upright tilting CT scanner's radiation shielding needs are comparable to standard CT scanners.
• The assumption of an isotropic scatter source is valid for radiation protection planning.
• No unique shielding modifications are necessary for this new scanner design.