Photon fluence spectra from various medical X-ray imaging systems measured using a compact cadmium telluride spectrometer

Abstract

This study presents the measured X-ray fluence spectra emitted by 15 diagnostic and interventional radiology X-ray imaging devices. The results, comprising more than 180 different spectra, may be used as a compendium and as a basis for further studies in medical X-ray applications. The measurements were conducted using a compact cadmium telluride (CdTe) spectrometer at multiple sites across Europe. The measured half-value layer (HVL) values spanned a wide range, confirming the need for new reference radiation qualities (RRQs) for calibrating medical diagnostic dosimeters. A new set of copper-filtered RRQs is proposed based on existing RQR qualities with filtration complemented with 0.1 mm, 0.3 mm, and 0.9 mm Cu. The new RRQs were designed to comprehensively cover the clinically relevant tube voltage–HVL range of diagnostic and interventional radiology radiation qualities. This will help reduce uncertainties in dosimetry measurements for medical physicists and technical services. Effects of the voltage ripple, the difference of actual and nominal tube voltage, influence of the patient table with mattress, presence of rhenium in the anode, and anode ageing recognized in some measured spectra are illustrated. Influence of anode ageing is compared with SpekPy calculations. The findings underline the practical applicability and relevance of in-beam X-ray spectrometry under clinical conditions, but also describe the persistent challenges in implementing routine spectrometric measurements.