Density

Density

Engineering definition

A calculable value that describes the ratio of mass to unit volume: ρ = m/V. Different materials have different densities, and a material may be selected for an application based on its density.

Medical definition

1. The compactness of matter, tissue in the clinical setting, as determined by MRI, CT or bone scan (densitometry). Bone density is a measure of the mineral content of bone. Decreased bone density, or loss of bone mass, is associated with osteoporosis. This is a typically age-related condition, especially common in postmenopausal women, that carries an increased risk of fracture.
2. The degree of darkening of a radiographic image such as an X-ray. The greater the variety of densities, the greater the detail of the image.

Confusion

Clinicians use bone mineral density as one metric among others to guide treatment. Engineers often use density as part of a larger or more complex calculation, so the exact value or at least a good approximation is important to achieve a meaningful result. This may be another case where the engineer will be more concerned with the detail of the measured value than the clinician.