# characteristic curve

(redirected from*H and D curve*)

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Related to H and D curve: characteristic curve

## char·ac·ter·is·tic curve

sensitometric curve of radiographic film, a plot of the film density versus the logarithm of the relative exposure.

Synonym(s): H and D curve, Hunter and Driffield curve

## curve

(kurv) [L.**curvus**, bent, crooked]

A bend, chart, or graph.

### bell curve

Normal distribution.### curve of Carus

See: curve of Carus### characteristic curve

Sensitometric curve.### dental curve

Curve of Spee.### D log E curve

Sensitometric curve.### dose response curve

A graph charting the effect of a specific dose of drug, chemical, or ionizing radiation.

### dye-dilution curve

A graph of the disappearance rate of a known amount of injected dye from the circulation; used to measure cardiac function.

### epidemic curve

A chart or graph in which the number of new cases of an illness is plotted over time.

### Gaussian curve

Normal distribution.### growth curve

A graph of heights and weights, head circumference, and body mass index of infants and children of various ages. A line connecting the data points produces the curve. Usually the changes in height and weight are shown on the same chart. Growth charts are specific for age and gender.

### learning curve

The effect of learning or practice on the performance of an intellectual or physical task. The term describes the acquisition of competence with experience, time, and training.

### normal curve

Normal distribution.### receiver operating curve

Abbreviation:**ROC curve**

A plot of the fraction of true positives test results versus the fraction of false positive test results; the sensitivity of a test versus (1-the test specificity).

Synonym: receiver operating characteristic### sensitometric curve

In radiographic film analysis, the curve derived by graphing the exposure to the film versus the film density. Analysis yields information about the contrast, speed, latitude, and maximum and minimum densities of the film or film-screen system. Digital radiography systems exhibit linear curves.

Synonym: *characteristic curve*;

*D log E curve*; Hurter and Driffield curve

### curve of Spee

See: curve of Spee### Stephan curve

See: Stephan curve### survival curve

In radiobiology, a dose response curve.

### time-temperature cooling curve

The mathematical relation that plots the physical and chemical behaviors of dental (and other) materials as their temperature decreases over time.

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