Midterm Flashcards
Most state regulations require QC programs. A good one involves what 3 people?
Coordinator
Liscensed Medical physicist
Service engineer
What are the 3 steps of QC for x-ray generating equipment?
Acceptance of new equipment
-done by physicist. Check for current or get updated inspection.
Performance evaluation
-annual evaluation and routine maintenance
Correction protocol should begin whenever any problems are detected
-report to service engineer
How do you report equipment problems?
Document exactly what happened and when
Write down any error messages on console as they appear
Guidelines for testing equipment: 7 tests
filtration collimation focal spot size kVp calibration exposure timer accuracy exposure linearity exposure reproducibility
WHen does a medical physicist perform testing of equipment?
- newly installed machine
- at leats once a year
- if a major component ir replaced or recalibrated
WHo conducts performance evaluations?
Physicist
What does the generator do?
Generator provides electrical power for the tube, other parts of the machine and other functions
Powers x-ray tube to produce x-rays
Control panel allows radiographer to select:
mA - and the appropriate focal spot size for exam
time (mA x time = mAs: total number of x-rays)
kVp (the energy of the x-rays in the beam)
in some cases: manual or automatic exposure timing
What are the 3 types of generators commonly used in chiro offices?
- single phase (half or full wave rectification) - old
- Three phase (6 pulse 12 pulse)
- high frequency or constant potential - newest
-same components
-differ in:
complexity
cost (high frequency : approx. $4,000 - 5,000)
efficiency in producing x-rays (high frequency higher energy)
exposure to the patient: (high frequency less exposure)
Annual generator & x-ray production test
kVp delivered during exposure must be within ± __% of the selected kVp. A variation of __-__ kVp affects patient dose and image density
5
2-3
Exposure timer – __ __ test must be tested annually
patient dose is directly affected by exposure time - very important
accuracy must be within ± __% for times greater than 10 milliseconds
below 10 milliseconds ± __ % is acceptable
spinning top
5
20
What is x-ray unit’s ability to produce a constant radiation output for the same mAs using different combinations of mA and time?
Linearity
Linearity test must be performed annually.
a dosimeter is used to measure radiation intensity which should be within ± __%
10
What is the same combination of kVp, mA and exposure time producing the same density and contrast every time called?
Reproducibility
should be within +-5%/ performed annualy
What tools can be used to test the focal spot?
Pinhole camera
Slit camera
star pattern
What are some ways to prolong tube life?
- avoid excessive exposure
- use a warm up procedure- 3 exposures, 5 sec apart, start low with large focal spot
- avoid unnecessary long exposure times
- use tube rating and cooling curve charts
- avoid high mA
What are 3 types of filtration?
inherent- from machine design i.e. glass tube
Added (aluminum between x ray and collimator)
COmpensation
Gonad shield face tube side is made of ___ and __ side is against patient
copper
aluminum
What is minimal acceptable filtration?
2.5mm Al (HVL) equivalent
What isan example of an x-ray and light beam alignment test?
If out of alignment +-__% of the SID additional anatomy is exposed.
9 penny test
2%
**Should be performed twice a year
WHat is the inverse square law?
Intensity of teh radiation is inversely proportional to the square of the distance
WHat is the anode heel effect?
Variation of x-ray intensity
- Anode less intense, cathode more
- can be used to balance body part density
- anode-cervical
- cathode-lumbar
What is best veiw to see z joints in C spine?
Lateral
What is best view to see IVF in C spine?
45 degree post. oblique
What is best view to see Z joints in T spine?
70 degree post. oblique
What is best view to see IVF in T spine?
Lateral
What is best view to see Z joints in L spine?
45 degree post. oblique
What is best view to see IVF in L spine?
Lateral
Where is central ray for AP pelvis?
Horizontal: @ ASIS, @ 1.5 inches below top of iliac crest
Vertical: Midline
SID for AP pelvis
40”
What do you have the pt do with their feet on AP pelvis?
Int. Rot. 15 degrees
Where do you measure for AP lumbar and what does it demonstrate?
Measure 1 ½” above the level of the Iliac crest from front to back
Demonstrates T12-SI Joints
Where do you measure for AP lumbosacral and what does it demonstrate?
Measure at the level of the Iliac crest from front to back
Demonstrates T12- Coccyx (to include SI Joints
Where do you measure for AP lumbopelvic and what does it demonstrate?
-Measure at the level of the ASIS from front to back
-Internally Rotate feet 150
-Demonstrates T12- Ischial Tuberosities,
Iliac Crests, Femoral head and necks
Where is CR for Lat. Lumbosacral? Where is vertical ray?
- Top of iliac crest
- b/w ASIS and PSIS
What does lateral lumbosacral demonstrate?
T12-coccyx
AP thoracic CR location and vertical ray location
- Inferior Scapula border
- Midline
*suspend inspiration
Where do ou measur for AP thoracic?
Over the shoulder from sternum to T spine
What does AP thoracic demonstrate and what is SID?
T1-T12
SID= 40”
Where is Vertical Ray for Laying down Lateral thoracic?
Posterior to humeral head
*no tube tilt
How do you measure for Lateral thoracic?
Side to side under the arms, may have pt. inhale and hold
Wjat does lateral thoracic demonstrate?
C7-L1
Where to shoot on Lat. thoracic if pt. has scoliosis
into concavity
*Shoot into the cave!
When is swimmer’s view taken?
When the lat. thoracic doesnt reveal upper thoracic or lateral cervical does not reveal lower cervical region
Tube tilt for swimmer’s view
Caudal 5 degrees
Pt. position for swimmer’s view
Coronal plane is rotated 10-20 degrees off of perpendicular to the bucky with the arm next to the bucky flexed and the arm next to teh tube extended.
-or pt’s coronal plane perpendicular to teh bucky with arm next to buck extended and the shoulder next to the tube hyper-depressed
LAteral Cervical SID and Patient position
72”
- pt. erect in a true lateral position
- Adjust the neutrality of the patient’s head so that an imaginary line between the inferior mastoid tip (or ear lobe) and the maxillary (Anterior Nasal) spine (acanthion) is horizontal (Parallel to the floor).
- Maximally depress pt’s. shoulders (may need sandbags)
Where is CR for Lat. Cervical?
Centered at level of C4 along plane of mastoid tip
Breathing instructions for lateral cervical
Exhale, then hold
- must see occiput to T1
Pt. position for APOM
Slight head extension, so that imaginary line between the mastoid tip and bottom of upper teeth are horizontal.
-open mouth as wide as possible
CR for APOM
Through center of open mouth
AP lower cervical structures demonstrated
C2-T2
Where to measure for Ap lower cervical and SID
C4 level
40”
Cr angle for AP lower cervical
15 degrees cephalad
PAtient position for AP lower cervical
facing tube, raise chin and extend head so angled central ray is in a line from the lower edge of the chin to base of occiput
Cervical Oblique SID
40
CR for Ant and Post cervical oblique
Ant- angle of the mandible
Post- Thyroid Cartilage
Lumbar Oblique SID
40
Lumbar oblique film size
14 x 17
Where to measure for lumbar oblique
level of L-3 obliquely
CR for anterior lumbar oblique
Vertical and horizontal CR is directed 1” lateral from L3 spinous on side closest to the tube
CR for Posterior Lumbar oblique
Vertical: 2” medial to teh ASIS on side closest to tube
Horizontal: 1” above iliac crest pn side closest to the tube
