BUSHONGS

photographic effect

is not fully understood and continues to be studied

so too the physics of photostimulable luminescence

is not fully understood.

CR

does not require a darkroom.

The diameter of the laser beam

determines the spatial resolution of the CR imaging system.

IPs

should be used soon after the erase cycle has been completed.

Small laser beam diameter

is critical for ensuring high spatial resolution.

Sampling and quantization

are two processes of analog-to-digital conversion (ADC).

A 14-bit CR image

has 16,384 gray levels.

CR should be performed

at lower techniques than previous screen-film radiography.

Digital radiography is best described by three elements

—capture, coupling, and collection.

The CCD

has high sensitivity to x-ray exposure and a very wide dynamic range.

CsI/CCD

is an indirect DR process by which x-rays are converted first to light and then to an electronic signal.

CsI/a-Si

is an indirect DR process by which x-rays are converted first to light and then to an electronic signal.

Spatial resolution in DR

is pixel limited.

a-Se

is a direct DR process by which x-rays are converted directly into an electronic signal.

kVp

controls x-ray beam energy.

1 A

1 C/s

1 C/s

6.3 × 10^18 electrons per second

With a constant exposure time

mA controls the x-ray intensity and, therefore, the patient radiation dose.

X-ray energy

remains fixed with a change in mA.

Short x-ray exposure time

reduces patient motion blur.

mA and x-ray exposure time

are inversely proportional

mA1/mA2

= time2/time1.

mAs

is the controlling factor for x-ray intensity.

mAs

is one measure of electrostatic charge.

Distance

has no effect on radiation energy.

Source-to-image-receptor distance (SID)

affects IR response according to the Square Law.

Changing the focal spot for a given kVp/mAs setting

does not change the x-ray intensity or energy.

% voltage ripple

= (peak voltage – minimum voltage)/peak voltage × 100

Half-wave rectification

results in the same radiation energy that is produced by full-wave rectification, but the radiation intensity is halved.

Radiation energy

does not change when going from half-wave to full-wave rectification

Three-phase power

results in higher x-ray intensity and energy.

High-frequency generation

results in even greater x-ray intensity and energy.

Patient positioning must be accurate

because the specific body part must be placed over the AEC detector to ensure proper exposure.

Automatic exposure control (AEC) x-ray systems

are not completely automatic but require proper operation by the radiologic technologist.