X-ray bone densitometry apparatus

摘要

Radiological apparatus, such as bone densitometry measurement systems that utilize a penetrating radiation source (52), such as an x-ray source is provided. The apparatus includes a patient table (50) with a length extending along a Y-axis and a width extending along an X-axis and a C-arm supporting, for example, an x-ray source at one side of the table and an x-ray detector (54) at an opposite side of the table such that the source and detector are aligned along a source-detector axis. The source is selectively energized to emit a fan beam (3a) of x-rays which conform to a beam plane which is transverse to the Y-axis and contains the source-detector axis. Either, or both, the C-arm (56) or the table are selectively movable relative to the other along the X-axis, along the Y-axis, and along a Z-axis which is transverse to both the X-axis and the Y-axis, so that selected regions of a patient on the table can be selectively scanned with the fan beam of X-rays. In addition, the C-arm is selectively rotatable around a rotational axis extending along the Y-axis to selectively change the angle of the fan beam relative to a patient on the table. The apparatus of the present invention provides various functions that complement and enhance the scanning function and resulting images derived from detected x-rays. For example, the apparatus has a multi-position attenuator mechanism (6c) for placement of different attenuating materials in the radiation beam. The apparatus also includes a detector response flattener coupled to and responsive to the output of detector elements in the x-ray detector. A dark current system interleaves the detector outputs with dark current responses of the detector elements and accounts for dark current characteristics of the elements. The apparatus includes an optical crosshair device (12c) that projects a visible crosshair coaxial with the source-detector axis, and patient positioning aides operative in conjunction with the patient table which facilitate positioning of x-rays and the patient for certain bone density measurements. The apparatus of the present invention may also be constructed as a portable unit suitable for transportation between rooms of a medical facility through generally standard doorways. The portable unit has a base portion capable of rolling ambulation by at least one human operator during transportation and selective stabilization on a floor for patient scanning, and a patient table. The patient table includes a central portion coupled with the base portion, and at least one table leaf coupled with the table central portion for extending table length parallel to the Y-axis.