[Measurement Accuracy of CT Beam Width with a Portable Flat-panel Detector]

Area of Science:

• Medical Imaging Physics
• Radiological Technology

Background:

• Computed radiography (CR) systems have been standard for clinical X-ray imaging.
• Portable flat-panel detector (FPD) systems are increasingly replacing traditional CR devices.
• FPD systems present a potential alternative for measuring CT beam width.

Purpose of the Study:

• To evaluate the accuracy of portable flat-panel detector (FPD) systems for measuring computed tomography (CT) beam width.
• To compare the measurement accuracy of FPD systems against traditional CR systems.

Main Methods:

• A CR cassette and an FPD were positioned at the isocenter for axial CT scans.
• Pixel values were measured under varying tube currents (10-40 mA) and a fixed tube potential (80 kVp).
• A double exposure technique with copper and lead shielding was used to measure beam widths (40-160 mm) and prevent saturation/artifacts.

Main Results:

• Log-linear relationships were established between pixel values and radiation exposure (up to 12.5 mAs) for both CR and FPD systems.
• Statistical analysis demonstrated equivalent measurement accuracy between the CR and FPD systems.
• Confidence intervals confirmed the non-inferiority of FPD measurements.

Conclusions:

• Portable FPD systems are suitable for measuring CT beam width.
• The accuracy of FPD systems is comparable to that of CR systems for this application.
• FPD systems can be reliably used as a substitute for CR in CT beam width measurements.