Trabecular bone mineral density (TBMD) was measured in vivo in the calcaneus by a new method that uses the ratio of coherent to Compton-scattered photons arising from irradiation of a small volume of trabecular bone by a gamma ray source with highly collimated geometry. TBMD values for healthy men (22-77 years) were in the range of 180-357 mg/ml, and values for healthy women (18-73 years) were in the range of 160-321 mg/ml. In contrast, values in a small group of paraplegics were in the range of 90-199 mg/ml.

Adult↗

PubMed1984

Analyzing chemical data with computers: errors & pitfalls.

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Chemistry Techniques, Analytical↗

PubMed1973

Pollution. Heavy metals: a review of lead.

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Air Pollution↗

PubMedDate not supplied

Method for registering brain SPECT and MR images.

We have developed a simple method for locating functional regions of interest on successive SPECT scans obtained at different times and for locating neuroanatomical regions defined with MR on functional images obtained with SPECT. Plastic molds are made for each external auditory meatus and the glabella. A pocket is then made in each mold in which either a 57Co disk (for SPECT) or an identical disk containing CuSO4 solution (for MRI) can be placed. Transaxial tomographic slices are reconstructed with the same slice thickness in the two modalities. The SPECT software rotates both SPECT and MRI reconstructed images so that the three 57Co markers lie in one SPECT reference plane and the three CuSO4 markers lie in one MRI reference plane. Corresponding SPECT and MR images may then be displayed simultaneously to locate chosen regions of interest. The technique was validated by taping test markers to the forehead of 12 subjects; the difference between the positions of the centers of the test markers on SPECT and MR scans was within 1 SPECT acquisition pixel size.

Brain↗

PubMedDate not supplied

Quantitative assessment of bone mineral by photon scattering: accuracy and precision considerations.

A method to determine the bone mineral density of the calcaneum has been reported earlier by our laboratory. In this method, the calcaneum is irradiated by a 60-keV photon beam from 241Am source and both the coherent and Compton scattered photons are detected by a high-purity Ge detector. The bone mineral density is determined by measuring the ratio of coherent-to-Compton scattered photons. The accuracy and the precision (in vitro) of the method are reported in this paper. The accuracy was determined to be 5%. This was obtained by comparing the bone mineral density values of cadaver calcanea measured directly by Archimedes' volume displacement method with the values measured by the scattering method. The precision was determined to be 3% by measuring the bone mineral density of a calibration phantom intermittently over a ten-month period by the scattering method.

Bone and Bones↗

PubMedDate not supplied

Quantitative assessment of bone mineral by photon scattering: calibration considerations.

The ratio of the coherent-to-Compton photons scattered from bone can be used to measure its mineral density. Conversion of this ratio (R) to bone mineral density (BMD) requires calibration using bone simulating phantoms. The widely used aqueous solution of K2HPO4 proved unsatisfactory for calibration purposes when using the coherent-to-Compton technique. These solutions differ markedly in their scatter spectra and composition from trabecular bone. In this study a new and more realistic series of phantoms is proposed which simulates well the trabecular bone of the calcaneum. These phantoms are made of bone ash suspended in white petrolatum in varying concentrations. A calibration curve has been established using these phantoms with a range of BMD values of 0 to 347 mg/cm3. The scatter spectra, and range of R values and BMD of these phantoms are in very good agreement with those of real trabecular bone. A measuring device has been built for the determination of the BMD of the calcaneum by using the established calibration curve.

Biophysical Phenomena↗

PubMedDate not supplied

A study of the homogeneity of the trabecular bone mineral density in the calcaneus.

In the past our laboratory has reported a method of measuring trabecular bone mineral density (TBMD) in the calcaneus in vivo by using the coherent-to-Compton scattering ratio. In the present work the distribution of TBMD in the calcaneus has been studied, and the reproducibility of this technique in vivo has been determined. It is found that although the TBMD may vary within the calcaneus, a region exists over which the variation in density is not large. This region coincides with the midportion of the heel and is the site chosen for the measurement of TBMD by the coherent-to-Compton scattering ratio technique. The reproducibility of this technique in vivo has been determined to be 3.4%.

Bone and Bones↗