A method for calculating the dose length product from CT DICOM images

Area of Science:

• Medical Physics
• Radiological Sciences
• Imaging Technology

Background:

• Accurate patient dosimetry in CT examinations relies on CTDI(vol) and DLP.
• These metrics are influenced by various scan parameters and scan length.
• Objective auditing of patient doses is crucial for radiation safety.

Purpose of the Study:

• To develop and validate a software-based method for calculating CTDI(vol) and DLP from DICOM CT images.
• To enable objective auditing of patient radiation doses in CT examinations.
• To assess the accuracy of the developed method across different CT scanners.

Main Methods:

• A software tool was developed to automatically extract DICOM header information.
• The software calculates individual image contributions to CTDI(vol) and DLP.
• The method was validated using data from actual CT examinations on three multislice scanners with activated automatic exposure control.

Main Results:

• Calculated DLP values showed good agreement (±5%) with displayed values.
• Calculated average CTDI(vol) values agreed well for two of three scanners.
• One scanner overestimated displayed CTDI(vol) by approximately 25%.

Conclusions:

• The developed software method is a valuable tool for radiation dose surveys.
• It facilitates objective auditing of patient doses in CT examinations.
• The method can also investigate differences in tube modulation techniques across scanners.