Densitometry


Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
Related to Densitometry: Bone densitometry

Densitometry

 

a branch of photographic sensitometry devoted to measurements of the absorption and scattering of light by developed photographic layers.

The methods of densitometry make possible the quantitative evaluation of the final photographic effect based on the optical density of blackening in the photosensitive layer. There is a nearly linear relationship between the surface concentration of silver in the blackened area and the optical density; their ratio is called the photometric equivalent of blackening. The optical density increases with the degree of dispersion of the silver in the blackened area. Correspondingly, the extent of the optical usefulness of the silver in the blackened area increases with the disperseness of the silver halide in the original light-sensitive layer and with the relative magnitude of the exposure of this layer to light. Because of the nonhomogeneous nature of the blackened areas, the light absorption in these areas is accompanied by strong diffusion. Therefore, the magnitude of optical density depends on the geometric structure (aperture) of the light beams that are incident on the blackened area and are directed to a receiver after passing through the blackened area.

A distinction is made between regular density (D ║) and integral density (DE), which are measured upon illumination of the blackened area by a beam of parallel light rays and upon reception, in the first case, of only that part of the light beam that has not changed direction during passage through the blackened area and, in the second case, of the entire light beam. In addition, diffuse density (D#), which is measured using an ideally diffuse beam of light to illuminate the blackened area, and effective density (D ψ), which is measured under intermediate conditions encountered in practice, are also distinguished. The difference D ║ -DE is a measure of the light diffusion in blackened areas. The diffuse density is commonly used in sensitometry.

The optical density of blackening is measured using densitometers and microphotometers.

The measurement of color fields in developed materials for color photography constitutes a special branch of densitometry.

References in periodicals archive ?
EggQus is light, compact and versatile compared to conventional ultrasound bone densitometry systems.
At this point, it is physicians' concern for patients, not the payment, that motivates them to continue to offer bone densitometry services, said Dr.
It's important to not just read the densitometry report but to look at the scan, he added.
2002 Densitometry Devices Approved by the Food and Drug Administration, in Bone Densitometry for Technologists.
market for bone densitometry scanners will be valued at almost $61 million.
chemiluminescence, fluorescence and autoradiographic densitometry colony counting and documentation system, and cell fluorescence analyzer autofluorescence calculator 1pc.
TechNavio's analysts forecast the Global Bone Densitometry market will grow at a CAGR of 3.
Adding in the results of the peripheral scan moved seven patients (23% of the normal group) out of the normal range and increased the numbers of osteopenic and osteoporotic patients, the investigators reported in a poster presentation at the annual meeting of the International Society for Clinical Densitometry.
Densitometry is being used more frequently to detect and treat diseases in childhood that can lead to osteoporosis in older adults, but there is a lack of consensus on how to acquire and interpret data in children and adolescents.
He recommends densitometry for women aged 65 years and older and postmenopausal women with risk factors for fracture.
The ISCD is a not-for-profit multidisciplinary professional society with a mission to enhance knowledge and quality of bone densitometry among healthcare professionals, to provide continuing education courses for clinicians and technologists, to increase patient awareness and access to bone densitometry, and to support clinical and scientific advances in the field.
The Women's Imaging Center at Rye Brook will provide services completely dedicated to women's health, including both conventional and digital mammography, ultrasound, 3-D Imaging, and bone densitometry.