Organ dose calculation in CT based on scout image data and automatic image registration.

Area of Science:

• Medical Imaging
• Radiological Physics
• Computational Anatomy

Background:

• Computed tomography (CT) is a major source of cumulative radiation exposure in medical imaging.
• Accurate patient radiation exposure history is crucial for effective management and justification of radiological procedures.

Purpose of the Study:

• To develop and validate an automated image registration technique for precise organ dose calculation in CT examinations.
• To improve the accuracy of cumulative radiation dose tracking for individual patients undergoing CT scans.

Main Methods:

• Co-registration of planning radiograph (scout) images from thoracic and abdominal CT scans with a reference trunk CT scout image.
• Utilized 2-D affine transformation and normalized correlation for image registration.
• Converted longitudinal scan range coordinates to slice locations on anthropomorphic models for organ and effective dose calculations.

Main Results:

• Achieved an average z-location deviation of 6.2 mm between patient images and the reference scout image.
• Organ doses ranged from 0 to 28.0 mGy, and effective doses ranged from 7.3 to 14.5 mSv.
• Mean dose deviation was 1% for fully irradiated organs, 5% for partially irradiated, and 22% for non-irradiated organs post-registration.

Conclusions:

• The automated image registration method for CT scout radiographs is feasible and effective.
• This technique enables accurate determination of individual scan ranges for calculating organ dose values.
• The method supports automatic organ dose calculation in CT, facilitating patient radiation exposure monitoring.