principles sem 2 final

function of lead shutters in a collimator box

absorbs primary radiation at the edges of the beam

automatic collimation is produced by

a sensor in the bucky tray

the field light of a collimator is obtained from

a light bulb and mirror

which filter is shaped like a trough

compensatory filtration

a decrease in filtration has what affect on IR exposure

increases it

a decrease in filtration has what affect on DOSE

increase

this would help reduce scatter

collimation

the window of the xray tube produces what type of filtration

inherent

increasing filtration has what affect on the average energy of the photons

increases the average energy

a radiographer can remove which one of these filters

compensatory

which exam is appropriate for a trough compensatory filter

PA chest

which filter makes the exposure more equal on the image

compensatory

the amount of total filtration required for xray tubes tubes over 70 kvp is

2.5 mm aluminum equiv

focused grid

lead strips are angled to match the angle of photons in the primary beam

crossed

criss cross, wafer, two parallel grids at right angles to one anothe

grid ratio

height of strip/ interspace

higher grid ratio =

more scatter radiation

grid frequency

number of grid lines per inch ( normal range is 60-110 inch)

grid cut off reasons

not centering to middle of grid , angulation, placement (like upside down), Wrong SID

grid focusin distance

SID range for that particular grid focus that mirrors primary beam

Moire effect

when a CR grid frequency matches the reader laser frequency, eliminate by using high frequency grids

grid ratio

new/old x New mass

ideal K factor

1.5- 2.5

what material is used to make an added filter

aluminum

tool for imaging ability to record two adjacent structures as separate exam

line pair resolution grid

another word for Penumba

blurirng

edge gradient

edge sharpness of bones (good, want)

resolution is controlled by

focal spot size, oid, sid

unsharpness equation

FSS x OID/ SOD

grid ratio

relationship between the height of the lead strips and the distance between them

Collimation size and multiplier

14×17=1 , 10×12= 1.25, 8×10= 1.40,

collimation size rule equation

new/old x old Mas

inherent filtration

.5-1mm, BUILT IN tube, lead glass window, tube housing

Added filtration

collimator and mirror, used when machine ages they take some filter away

Total filtration

all filtration added together must be 2.5mm, for above 70 kvp

compensatory filtration

for a more uniform density/ exposure, used to make a body part same thickness. (put thicker portion over thinner body part) (heel, CSP, TSP)

anode heel affect

you put the thinner part of the body under the anode side

air-gap

reduces scatter, by preventing it from reaching the image

lead blockers

absorbs unabsorbed primary beam and scatter, downfall is that exposure index number gets confused,

compression

decreases amount of matter, less matter= less scatter,

what is the measure of radiographic quality

image sharpness and visibility

most scatter radiation is produced in

the patient

scattered radiation has less or more energy compared to primary radiation

less

scattered radiation that hits the xray film

increased density and lower contrast

what reduces the PRODUCTION of scatter radiation

collimation

what type of contrast does a large amount of scattered radiation produces

long scale

which is the most common type of grid pattern in use

focused

which one of the grid patterns matches the pattern of primary beam

A

define grid ratio

the height of grid strips compared to the distance between grid strips

unwanted absorption of the primary radiation by th e grid is called

grid cut-off

the range of acceptable source-image distances that can be used on a grid is called

focal range

grid cutoff is more likely to occur

in a portable radiography

which one of these maneuvers will produce grid-cut off

angling beam ACROSS grid lines, beam out of focal range, angling so the CR isnt perpendicular

most scattered radiation will be produced on a collimation size of

14×17

adding more filtration does what to the beam

increases average energy

adding more filtration does what to contrast

decreases it

adding more filtration does what to density

decreases

what type of filter results from design of xray tube

inherent

the thick end of the wedge compensatpry filter should be placed on

thin body part

th airgap technique uses a large OID and a

large SID

when using a lead blocker it should be placed

on the table in unabsorbed radiation

when using a trough filter it should be placed

in the track under the xray tube

what one would produce the least scattered radiation regular abdomen or PA abdomen or lateral abdomen

a PA addomen

does compensatory filtration require technique compensation

no

visibility

overall quality of the finished radiograph

additive kvp

when you have to add techniquw

to control motion you want

high MA, short time

15% rule

controls motion , decreases dose