Reproducibility of image quality for moving objects using respiratory-gated computed tomography: a study using a...

Area of Science:

• Medical Imaging
• Radiation Oncology
• Radiotherapy Physics

Background:

• Accurate radiation treatment planning for movable tumors requires reproducible computed tomography (CT) imaging.
• Respiratory motion significantly affects imaging quality and treatment accuracy.

Purpose of the Study:

• To evaluate the reproducibility of CT imaging quality under various respiratory motion conditions for radiation treatment planning.
• To determine the impact of regular and irregular respiratory motion on the accuracy of object volume and shape reproducibility.

Main Methods:

• A thorax dynamic phantom simulated regular (2.5-4s cycle, 4-10mm amplitude) and irregular respiratory motions.
• CT images were acquired six times using respiratory-gated data acquisition.
• Reproducibility was assessed by calculating volume variations and shape overlap percentages.

Main Results:

• Significant variations in volume and shape reproducibility were observed with changes in the respiratory cycle.
• Irregular respiratory motion led to further inferior shape reproducibility, with overlap as low as 35.26% in mixed cycle groups.
• Amplitude variations showed no significant impact on volume or shape reproducibility.

Conclusions:

• Respiratory cycle changes are a critical factor reducing image quality reproducibility in respiratory-gated CT.
• These findings highlight challenges in radiotherapy for movable tumors due to motion-induced imaging inconsistencies.