Midterm | RADIOGRAPHIC PHOTOGRAPHY: Sensitometry & Characteristic Curve

Question 1

Sensitometry as a photographic science has been credited to two Americans

Answer 1

Ferdinand Hurter and
Vero Charles Driffield

Question 2

Ferdinand Hurter and Vero Charles Driffield first proposed a form of evaluation of the performance of photographic material in the year

Answer 2

1876

Question 3

The main interest in radiography is how the film
will react to (apparently) _____________, although
usually the real interest is how the film will react
to the light produced by the ___________________.

Answer 3

x-radiation; intensifying screen

Question 4

The study of the relationship between intensity of exposure of the film and the blackness after processing.

Answer 4

SENSITOMETRY

Question 5

The measurement of the sensitivity of the film towards radiation.

Answer 5

SENSITOMETRY

Question 6

is normally the blackness of the film.

Answer 6

Photographic density

Question 7

is the graph which shows the relationship between the log of exposure and the density produced in the film.

Answer 7

Characteristic curve

Question 8

It increases with exposure.

Answer 8

Photographic density

Question 9

Density of an image is approximately proportional to the amount of _________ present in emulsion.

Answer 9

silver

Question 10

conveniently express large differences in numbers on a small scale.

Answer 10

Logarithms

Question 11

If the films are _______________, the resulting density is equal to the sum of densities.

Answer 11

superimposed

Question 12

The human eye seems to respond to different tones in a way which is approximately logarithmic. A density of two looks twice as dark as a _________________.

Answer 12

density of one

Question 13

enable a much wider range of values to be appreciated with understanding

Answer 13

Logarithmic scales

Question 14

equal increments have the __________ ratio.

Answer 14

same

Question 15

Two pieces of apparatus are needed to construct a characteristic curve:

Answer 15

Optical step wedge
Densitometer

Question 16

Optical step wedge is AKA

Answer 16

sensitometer

Question 17

measures OD (optical density)

Answer 17

Densitometer

Question 18

as the film or the film-screen is subjected to greater and greater exposure, a point is reached when further increase in exposure can’t result any increase in density. thus, the film achieves a maximum level of density known as

Answer 18

Dmax (maximum density/over-exposed region)

Question 19

in this region, subject contrast do not produce image contrast and no subject detail can be visualized

Answer 19

over-exposed region (dmax)

Question 20

it has small density (around 0.5), even at the starting point although there has been no exposure or only a very small exposure

Answer 20

Dmin (minimum density/under-exposed region)

Question 21

this is the result of base density plus fog

Answer 21

Dmin

Question 22

the useful range of optical density

Answer 22

0.25 to 2.5

Question 23

most radiographs have an optical density of

Answer 23

0.5 to 1.25

Question 24

base plus fog optical density is

Answer 24

0.1 to 0.3

Question 25

in this region, change in exposure causes a significant change in density

Answer 25

LINEAR RESPONSE/ STEEP SLOPE/ REGION OF CORRECT EXPOSURE

Question 26

the ___________ the slope of the characteristic curve, the higher the contrast

Answer 26

steeper

Question 27

The phenomenon when subjected to exposures many times greater than that required to achieve D max

Answer 27

SOLARIZATION

Question 28

in solarization, the film responds in the opposite way than normal. producing a reduction in image density called

Answer 28

reversal

Question 29

LAYERS OF CASSETTE

Answer 29

FRONT COVER
PRESSURE PAD
BASE
REFLECTIVE LAYER
PHOSPHOR
SUPERCOAT
EMULSION
ADHESIVE
BASE
ADHESIVE
EMULSION
SUPERCOAT
PHOSPHOR
REFLECTIVE LAYER
BASE
PRESSURE PAD
LEAD BACKING
BACK COVER