How do you control the amount of distortion that is seen on xray?
following the “basic” rules
- the long axis of part is parallel to long axis of IR
- the CR is perpendicular to the part and IR
- the center of the part is centered to CR and IR
how do we control magnification distortion?
keep the part as close to the IR as possible
compensate by increasing SID if there is notable IOD that cannot be reduced
how do we control shape distortion?
no rotation or tilt of the part
no tube tilt
can distortion be useful?
yes, when isolating a specific part
what are the exceptions to the 40” SID rule?
all lateral cervical spine all oblique cervical spine lateral chest PA chest AP full spine
mastoid tip
C1
thyroid cartilage
C4
vertebral prominens
C7
sternal notch
T2
sternal angle
T4
xyphoid tip
T10
iliac crest
L4/5
ASIS
S2
greater trochanter
pubic symphysis
coccyx tip
ischial tuberosities
bottom of pelvis
what are the commonly used planes for xray?
posterior/dorsal anterior/ventral transverse mid axillary occlusal
how does one accomodate the IR size and orientation?
it needs to be large enough for the part being xrayed
size and orientation matched
collimation to part size and orientation is the most important
what are some advantages to collimation to part size and orientation?
limits amount of radiation to patient
controls unwanted scatter
how large should the cassette be?
just as large or larger than the part being xrayed
where does the ID blocker get placed?
away from anatomy of interest
what are the effects of respiration?
controls voluntary motion
phases change placement of anatomy
what happens when we inhale?
diaphragm moves down (thoracic area)
shoulders move up (cervical area)
what happens when we exhale?
diaphragm moves up (lumbar area)
shoulders move down (cervical area)
what should we have the patient do if we want a chest xray (breathing wise)?
take a deep breath and hold
when we measure with calipers, we measure in…
centimeters
how do we measure with the caliper?
in the direction CR travels through the body
at centering point
what is the use of calipers?
determines amount of exposure needed
how do we place anatomical markers?
according to patient’s anatomy
when do we put an R on patient’s right or L on patient’s left?
on AP, PA and oblique films
how do you know which marker to put on for laterals?
use the side touching IR
where should anatomical markers be placed?
inside light, outside anatomy
what happens if you put the anatomical marker on the wrong side?
repeat the film
what is the use of a flat aluminum filter?
even out radiographic density
protects patient from some exposure
produces consistent radiographic density throughout the part of interest
where is the flat aluminum filter placed?
between xray beam and patient
over the thinnest portion of intended anatomy
what do you need to do for patient prep?
obtain accurate history determine if pregnant remove clothin in affected area, patient in gown remove artifacts explain procedure measure with calipers shield patient appropriately
what do you want to do when obtaining history?
identify the area of complaint and history regarding injury
What do we do if the patient is pregnant?
explain importance of radiation safety
delay exam, if possible
shield fetus if necessary
what is the 10 day rule?
the safest time to xray women of childbearing age is within the 10 day period after onset of menstruation
what’s the difference between artifacts and foreign bodies?
artifacts can easily be removed
foreign bodies cannot be easily removed
what do you need to do when explaining the procedure to your patient?
use appropriate terminology for patient understanding
appropriate volume
validate response
what do you do when you are about to measure patient with calipers?
alert patient before touching
do this for each projection
set control pattern per measurement
how should you shield your patient?
use 1/2 apron or gonadal shield between the xray beam and patient
don’t cover pertinent anatomy