Entrance surface dose during three-dimensional imaging with a flat-panel detector angiography system

Area of Science:

• Medical Imaging
• Radiation Dosimetry

Background:

• Three-dimensional (3D) imaging utilizes advanced techniques for enhanced visualization.
• Accurate measurement of radiation dose, specifically entrance surface dose (ESD), is crucial for patient safety.
• Dose-area product (DAP) is a commonly used metric in radiation monitoring.

Purpose of the Study:

• To quantify the entrance surface dose (ESD) in a phantom during 3D imaging procedures.
• To assess the efficacy of using dose-area product (DAP) values for estimating patient ESD.

Main Methods:

• Utilized an angiographic unit with a digital flat-panel system for 3D imaging.
• Measured ESD and DAP on square phantoms of varying thicknesses (12-25 cm) and a human-shaped phantom.
• Acquisitions were performed over 5 seconds, with ESD measured at multiple surface locations.

Main Results:

• Posterior ESDs ranged from 7.3 mGy to 38.5 mGy across phantom thicknesses.
• A strong correlation (r=0.998) was found between DAP and posterior ESD, with a derived regression equation (D = DAP x 0.0014).
• Estimated posterolateral ESDs closely matched actual doses in the human-shaped phantom, with minor variations (<10%).

Conclusions:

• The measured ESD for a single 3D imaging study is significantly lower than levels associated with radiation skin injuries.
• DAP serves as a reliable and practical tool for estimating the maximum patient ESD during 3D imaging.