RAD 121 Carroll Chap 24-25-26-27

Within the automatic exposure control circuit, which of these is placed in the circuit immediately following the capacitor?

• thryatron

• magnetic relay switch

• transformer

• ion chamber

Which of the following is a typical minimum response time for an AEC circuit?

• 2 second

• 1 second

• 0.1 second

• 0.01 second

Most AEC “density” controls extend or shorten the exposure time in increments of:

• 50%

• 25%

• 15%

• 10%

Which of the following does not directly affect the degree of shape distortion in an image:

• centering of the object relative to the x-ray beam

• SID

• angle of the x-ray beam in relation to the object

• object thickness and shape

Shape distortion in a projected image is controlled by:

• distances

• alignment

• focal spot size

• x-ray tube movement

While positioning for an x-ray exposure, the most common purpose of angling the x-ray beam is to:

• sharpen images

• desuperimpose images

• magnify images

• increase distance

With all other factors unchanged, if an object is tilted in relation to the receptor plate, the image shape distortion will:

• not change at all

• may be affected indirectly, but is not directly controlled by it

• decrease as a direct result

• increase as a direct result

The lumbar spine normally has a lordotic curvature (concave posteriorly). With typical x-ray beam divergence at 40" (100 cm) SID, the best way to position the lumbar spine so as to fully open all of the intervertebral joint spaces is:

• AP standing

• PA prone

• AP supine

The ability to distinguish adjacent details as being separate and distinct is the definition of:

• resolution

• subject contrast

• sharpness of recorded detail

• geometrical factors

The overall contrast resolution for an imaging system is measured by physicists as:

• quantum mottle

• spatial frequency

• modulation transfer function

• acutance