Bone densitometer
US4811373A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 27, 1987 |
| Grant date | Mar 7, 1989 |
| Priority date | — |
| Expiry date | Jul 27, 2007 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B6/4266
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In an x-ray bone densitometer, special calibration techniques are employed to accommodate variations. In one aspect, a bone-like calibration material is interposed and the system determines the calibration data from rays passing only through flesh. In another aspect, a rotating device carries the calibration material through the beam. The specific densitometer shown uses an x-ray tube operated at two different voltages to generate a pencil beam, the energy levels of the x-ray photons being a function of the voltage applied. An integrating detector is timed to integrate the detected signal of the patient-attenuated beam over each pulse, the signals are converted to digital values and a digital computer converts the set of values produced by the raster scan into a representation of the bone density of the patient. Multiple reference detectors with differing absorbers are used by the system to continuously correct for variation in voltage and current of the x-ray tube. Calibration is accomplished by the digital computer on the basis of passing the pencil beam through known bone-representing substance as the densitometer scans portions of the patient having bone and adjacent portions h…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.