relationships: radiographic technique

how is a decrease in kV by 15% compensated?

by doubling the mAs

how is an increase in kV by 15% compensated?

by decreasing the mAs by half

mA and time relationship

an increase in one factor will require a decrease in the other to maintain the same radiographic density

mA and time formula

(mA1/mA2) = (S2/S1)

reciprocity law

indicated that density of the image will remain constant as long as the total mAs exposing the image receptor is constant

TRUE or FALSE: time does not affect the penetrating ability of the x-ray photons

TRUE

distance

represents the length of the distance between the x-ray source to the imaging receptor

what does SID stand for?

source to image distance

what is the intensity of the x-ray beam affected by?

source to image distance

what happens to the number of photons and the intensity of the beam when SID is doubled?

number of photons is spread over an area four times the original area and the intensity beam is reduced to ¼ of the original density

inverse square law formula

(old I/new I) = (new D²/old D²)

what is beam intensity measured in?

roentgen (R)

what does the inverse square law apply to?

x-ray unit or radiation source

what does the inverse square law measure?

intensity and exposure rate

direct square law

as SID increases, so must mAs to maintain adequate radiographic density

direct square law formula

(new mAs/old mAs) = (new D²/old D²)

what does the direct square law apply to?

patient and radiographic exposure