Spectra of clinical CT scanners using a portable Compton spectrometer

Area of Science:

• Medical Physics
• Radiological Imaging Technology

Background:

• X-ray spectral information from CT scanners is crucial for accurate CT number conversion and quality assurance.
• Accurate measurement of X-ray spectra is essential for optimizing CT scanner performance.

Purpose of the Study:

• To design, validate, and apply a compact, portable Compton spectrometer for precise X-ray spectrum measurement in CT scanners.
• To enable improved quality assurance and performance evaluation of CT scanners.

Main Methods:

• Designed a Compton spectrometer with optimized shielding to minimize background noise.
• Reconstructed original X-ray spectra from Compton scattered spectra using Monte Carlo simulations.
• Validated the reconstruction method by comparing with direct and indirect measurements.
• Assessed the spectrometer in a clinical setting on multiple CT scanner X-ray tubes.

Main Results:

• Reconstruction method validated with good agreement (ratio 0.99) between directly and indirectly measured spectra.
• Measured X-ray spectra from medical CT scanners align with theoretical and manufacturer data.
• Demonstrated the spectrometer's ability to accurately capture X-ray spectra.

Conclusions:

• A compact Compton spectrometer was successfully developed, validated, and applied for CT scanner X-ray spectrum measurement.
• The spectrometer is easily deployable using CT scanner alignment lasers for rapid setup.
• The device is suitable for CT scanner commissioning, troubleshooting, and annual performance evaluations.