C J Kotre1, K J Robson. 1. 1 Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK.
Abstract
OBJECTIVE: To investigate the use of conventional diagnostic X-ray tubes for applications in which specialist microfocus sources are normally required. METHODS: A conventional diagnostic X-ray tube was used in conjunction with a range of apertures to investigate improvements in spatial resolution using a line-pairs test object. Phase-contrast effects were investigated by varying source-to-object and object-to-receptor distances using a 2-French catheter as a clinically realistic test object. RESULTS: For magnification radiography using a computed radiography receptor and conventional X-ray tube with a 1-mm nominal focus size, the limiting spatial resolution was improved from 3.55 line-pairs per millimetre, for a conventional contact image, to 5.6 line-pairs per millimetre, for a ×2 magnified view with a 250-µm aperture. For inline phase-contrast radiography, phase contrast enhancement of a 2-French catheter was demonstrated, and the expected trends with variations in source-to-object and object-to-receptor distances were found. Images of a neonatal phantom demonstrated a subtle improvement in visibility of a superimposed 1-French catheter simulating a percutaneously inserted central catheter for no increase in patient radiation dose. CONCLUSION: Spatial resolution improvement and visible phase contrast can be produced in clinically relevant objects using a pseudo-microfocus geometry at X-ray energies in the normal diagnostic range, using conventional diagnostic X-ray tubes and image receptors. The disadvantages of the proposal are the large distances required to produce phase contrast and limitations imposed by the resulting tube loading. ADVANCES IN KNOWLEDGE: It is possible to use conventional diagnostic X-ray equipment in applications that normally require microfocus X-ray sources. This presents some possibilities for clinical applications.
OBJECTIVE: To investigate the use of conventional diagnostic X-ray tubes for applications in which specialist microfocus sources are normally required. METHODS: A conventional diagnostic X-ray tube was used in conjunction with a range of apertures to investigate improvements in spatial resolution using a line-pairs test object. Phase-contrast effects were investigated by varying source-to-object and object-to-receptor distances using a 2-French catheter as a clinically realistic test object. RESULTS: For magnification radiography using a computed radiography receptor and conventional X-ray tube with a 1-mm nominal focus size, the limiting spatial resolution was improved from 3.55 line-pairs per millimetre, for a conventional contact image, to 5.6 line-pairs per millimetre, for a ×2 magnified view with a 250-µm aperture. For inline phase-contrast radiography, phase contrast enhancement of a 2-French catheter was demonstrated, and the expected trends with variations in source-to-object and object-to-receptor distances were found. Images of a neonatal phantom demonstrated a subtle improvement in visibility of a superimposed 1-French catheter simulating a percutaneously inserted central catheter for no increase in patient radiation dose. CONCLUSION: Spatial resolution improvement and visible phase contrast can be produced in clinically relevant objects using a pseudo-microfocus geometry at X-ray energies in the normal diagnostic range, using conventional diagnostic X-ray tubes and image receptors. The disadvantages of the proposal are the large distances required to produce phase contrast and limitations imposed by the resulting tube loading. ADVANCES IN KNOWLEDGE: It is possible to use conventional diagnostic X-ray equipment in applications that normally require microfocus X-ray sources. This presents some possibilities for clinical applications.