The AAPM/RSNA physics tutorial for residents: X-ray image intensifiers for fluoroscopy

Area of Science:

• Medical Imaging Physics
• Radiological Technology

Background:

• X-ray image intensifiers (IXIs) are crucial components in medical imaging, converting X-rays into visible light.
• They utilize input phosphors, photocathodes, and output phosphors to amplify faint X-ray signals.
• Cesium iodide is commonly used for input phosphors due to its high efficiency, reducing patient radiation dose.

Purpose of the Study:

• To explain the fundamental working principles of X-ray image intensifiers.
• To highlight the importance of conversion factors in specifying performance.
• To discuss image artifacts and performance degradation over the lifespan of an IXI.

Main Methods:

• Description of the photon conversion process from X-ray to light.
• Explanation of electron acceleration and focusing mechanisms.
• Discussion of factors affecting image quality, such as brightness gain and phosphor aging.

Main Results:

• Each X-ray photon can generate thousands of light photons, enabling image amplification.
• Image intensifiers are characterized by their conversion factors, measuring X-ray to light conversion efficiency.
• Image quality parameters like spatial and contrast resolution degrade over time due to aging.

Conclusions:

• X-ray image intensifiers are complex devices requiring careful management.
• Performance degradation is inevitable, necessitating proactive quality control.
• Regular quality control programs are vital for ensuring diagnostic accuracy and patient safety.