X-ray bone densitometry using a vertically scanning gantry

Abstract

The present invention provides a system that reduces the complexity of existing dual energy x-ray equipment which typically requires more complicated mechanisms to measure bone density, to a system with a single axis of mechanical motion and with a patient providing repositioning motions. This configuration allows for a much more compact design and smaller equipment 'footprint,' thus taking up less floor space in examination rooms and allowing for multiple uses of one room. The system of the present invention eliminates the need for a patient support table which can affect x-ray transmission because of the thickness and construction of the table which are dictated by the weight of the patient. The system includes a main cabinet or gantry enclosure which contains an x-ray source and ancillary support electronics and mechanisms. An extension arm positions a detector assembly on a side of the patient opposite to the source assembly and fixes the distance between the source and detector assemblies. The source and detector assemblies are capable of making dual energy bone measurements. The source assembly, detector assembly and extension arm form a gantry and the source assembly and detector assembly are confined to move in unison in a vertical scanning motion. A drive mechanism in conjunction with a precision guide rail provides a stable, smooth vertical scanning motion of the gantry. A counter balance system is provided to reduce the forces required to move the gantry. In addition, the extension arm may either fold or retract into the main cabinet to reduce the system volume when not in use.