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PubMedDate not supplied

[Digital bone densitometry].

Normal values of bone mineral composition were defined, based on examinations of 600 male and female volunteers of various age groups by digital roentgenodensitometry. The mineral compactness was found reduced in the patients with endocrine diseases, in subjects who participated in liquidation of the Chernobyl power plant accident aftereffects, and in those suffering from skeletal pains. The authors emphasize the value of digital roentgenodensitometry as a method for monitoring the efficacy of treatment of patients with endocrine diseases and chronic renal insufficiency.

Absorptiometry, Photon↗
PubMed1995

Magnetic resonance bone densitometry. Comparison of different methods based on susceptibility.

RATIONALE AND OBJECTIVES: Three different magnetic resonance techniques for the assessment of the density of trabecular bone are presented and compared. METHODS: All methods are based on the susceptibility difference between marrow and bony components. Localized spectroscopic (PRESS single voxel spectroscopy) and two different imaging approaches (FLASH gradient echo imaging and MAGSUS imaging) are demonstrated to be sensitive to the trabecular structures on application to the distal femur of a healthy volunteer. This region was chosen because a continuous rarefication of the trabecular density from the epiphysis to the metaphysis occurs physiologically. In addition, results from the heel-bones of five young healthy volunteers were compared with data from three patients with severe osteoporosis. RESULTS: All methods allowed differentiation between the two groups. Advantages and disadvantages of the methods concerning spatial resolution, preparation and measuring time, necessity of postprocessing, problems with shim adjustment, and occurrence of several chemical shift components are reported. The MAGSUS technique combines simple application and avoidance of postprocessing for at least qualitative assessment of bone density with sufficient spatial resolution. CONCLUSIONS: A reliable assessment of osteoporosis by magnetic resonance is possible in peripheral marrow regions of adults. Further studies are needed to establish standard measuring protocols.

Adult↗
PubMed1994

[Bone mineralization in Chilean children determined by dual photon bone densitometry].

In 198 school age children, aged 6 to 13 years, the bone mineral density (BMD) and total bone mass (TBM) was measured in total body, lumbar spine and hip, using a double beam photon densitometer with a Gd 153 source. An increase with age of BMD and TBM was found in all the analyzed areas. At 12 years of age, TBM and BMD of total body were higher in girls than in boys. BMD of lumbar spine was significantly higher in girls than in boys at ages between 11 to 13 years. BMD of lumbar spine and femoral neck of 9 years old females were 36% and 18% respectively, lower than values of young adult Chilean females. The importance of normal values of bone mineralization for the diagnosis of bone diseases and for the evaluation of programmes directed to solve this problems is emphasized.

Absorptiometry, Photon↗
PubMedDate not supplied

[Current methods and equipment in densitometry of the bone tissue].

In the past 15 years there has been an intensive development of methods and equipment for non-invasive quantitative determination of the mineral status of the human skeleton in the USA and some Western European countries. The specialized osseous densitometers which are based on photon absorptiometry and which use various radionuclides or an X-ray tube as a source of radiation have extensively spread.

Absorptiometry, Photon↗
PubMed1994

[Densitometry in suspected preclinical osteoporosis: quantitative computerized tomography versus dual energy roentgen absorptiometry].

The bone mineral density of 85 patients with suspicion of a preclinical osteoporosis was measured at the lumbar spine by using quantitative computed tomography (QCT) in single-energy technique (SEQCT) and dual-energy technique (DEQCT) as well as by using dual-energy X-ray absorptiometry (DEXA). Additionally, the bone density of 63 of these patients was measured at the left femoral neck using DEXA. DEQCT und DEXA of the lumbar spine showed only a moderate correlation (R = 0.75) and differed considerably concerning the classification of the patients as normals or individuals with a mineral deficit when compared with age-matched normals (relative mineral deficit). The DEXA proved to be susceptible to degenerative alterations of the lumbar spine. Because of the extremely low dose of radiation and the good reproducibility the DEXA could nevertheless be recommended as a method for the long-time progress control especially for younger patients. SEQCT and DEQCT showed a very strong correlation (R = 0.98). The SEQCT with its lower dose of radiation should be sufficient for a long-time progress control and in many cases also for the initial diagnostics. Significant but only moderate correlations were found between the bone density at the femoral neck and the DEXA or DEQCT results (R = 0.68 respectively R = 0.63) for the lumbar spine, so that the linear regression did not render any useable approximations. Sufficiently exact information about the mineralization status of a certain skeletal site can only be obtained by direct measurement.

Absorptiometry, Photon↗
PubMedDate not supplied

X-ray densitometry applied to the study of prenatal ossification.

To evaluate bone mass (BMC) and bone density (BMD) it is possible to utilize x-ray absorptiometry. This method is usually employed in clinical practice for the evaluation of metabolic osteopathies. The authors describe an application of this diagnostic technique to the study of the ossification pattern of the human vertebral column in pre- and post-natal life. On this regard, an ultra high resolution software allowed to analyze quantitative aspects of the ossification of small size vertebral bodies by lateral scans directly performed on bone specimens.

Absorptiometry, Photon↗
PubMed1993

Dosimetric implications of shifts in linear accelerator electron beam energy detected in routine constancy checks: a scanning film densitometry detection method.

The effects of change in electron beam energy are primarily manifest by changes in the range parameters of the depth ionisation/dose curve. Even for a change of up to 10% in the mean energy at the surface, E0, the dose to the depth of maximum on the central axis changes by less than 1%. Using as a limit of acceptability that the change in the therapeutic range (R85) should not be more than +/- 1.5 mm, the precision required by beam energy checking is that a change of 0.4 MeV in E0 should be detectable for all electron beams provided by the accelerator. To satisfy this criterion a routine method is proposed that uses therapy verification film exposed to the electron beam under a perspex wedge. The automatically processed film is then scanned with the densitometer of a beam data acquisition system (BDAS). The optical density versus distance plot is analysed using the BDAS computer that converts it to a quasi-depth dose curve and then calculates E0 and Ep,0 from the range parameters. The results for electron beams from "console" energies of 5 to 14 MeV show that the test criterion is within the capability of the method, and that the method is very practical for routine use in a quality assurance program.

Calibration↗