Ch. 5: Radiation Characteristics

determines the energy and penetrating power of radiaition

wavelength

shorter the wavelength = ____ penetrating power

more

the mean of penetrating ability of the x-ray beam

quality

What is quality controlled by?

kVp

maximum or peak voltage of an alternating current

kilovoltage

What kilovoltage is required for dental radiography? 

65-100 kV

increase kVp = ________ penetrating ability

increased

overal darkness or blackness of an image

density

increased kVp = ______ density

increased

how sharply dark and light areas are differentiated on an image

contrast

increased kVp = _______ contrast

decreased

What is a high contrast image good for detecting? 

caries

What is a low contrast image good for detecting? 

periodontal or periapical disease

interval of time during which x-rays are produced

exposure time

Exposure time is measured in what increments?

1/100th of a second

if you increase the kVp, then you must _______ the exposure time to compensate for the penetrating beam power.  

decrease

number of x-rays produced in a dental x-ray unit

quanity

regulates the number of electrons produced at the cathode filament 

amperage

What is quanity controlled by? 

mA

What mA is required for dental radiography?

7-15 mA

increased mA = ______ density

increased

if you increase the mA, you must ______ the exposure time. 

decrease

the product of the quanity and quality per unit of area per unit of exposure time

intensity

increased kVp = ______ intensity of the beam

increased

increased mA = ______ intensity of the beam

increase

increased exposure time = _______ intensity of the beam

increased

increased distance = _______ intensity of the beam

deacreased

intensity of radiation is inversely proportional to the square of the distance from the source of radiation

inverse square law

What do aluminum filters do?

remove the low energy, longer wavelengths, and less penertrating rays

the increased filtration from the thickness of a specified material (aluminum) that reduces the intensity by half

half-value layer

higher the half value layer = _______ penetrating power of the beam

higher