1a - Positioning Basics Flashcards
Radiographic Density
more dense tissue will appear LIGHTER on x-ray
- Thickness of bodypart affects density
Radiographic positioning
the placement of the bodypart between the Xray tube and the film (image receptor = IR)
How many views are needed when taking Xray?
Minimum of 2 opposing views
- Preferable at 90 degrees
“Series” of xrays
the minimum amount of xrays needed to complete the exam
- For insurance purposes
Projection
the path of the xray bean (CR) as it enters and exits the body
View
the beam’s perspective
Position
the placement of the body or part
- Upright(Standing or seated)
- Recumbent (Prone/supine)
- AP or PA
- Refer to bodypart against the IR
- Oblique:RAO, RPO, LAO, LPO
- Lateral:Left, Right
Lateral
the coronal plane that is perpendicular to IR
- Refer to the side touching the IR
Oblique
the body (or part) is rotated from normal Anatomic Position
Axial view
There is more than 10 Degree tilt between the part and CR
- Usually the tube is tilted
Tangential view
The CR intersects an object at only one point on the suface
- “Skimming a body part”
Decubitus view
Pt is recumbent, CR is horizontal, IR is vertical
- Checks for air/fluid levels
Air-fluid levels seen with which xray views?
demonstrated on upright and on decubitus views only
Basic rules for positioning
- CR is centered to the middle of the part (CR –> Center body part –> Center of film)
- The long axis of the bodypart is parallel to the long axis of IR
- CR is directed perpendicular to the part (and IR)
Controlling magnification distortion
- Keep bodypart as close to IR as possible
- Compensate by increasing the Source-to-Imagine Distance (SID) if there is notable OID that cannot be reduced
Shape distortion control
- No rotation or tilt of bodypart
- No tube tilt
When can distortion be helpful?
When isolating a specific bodypart
SID to minimize magnification distortion
- 40”
- Exceptions (need to use 72”)
- Lateral Cervicals
- Oblique Cervicals
- Lateral Chest
- PA Chest
- AP full spine
Topographic landmarks: Mastoid tip, Thyroid cartilage, Vertebral Prominens
- C1 = Mastoid tip
- C4 = Thyroid cartilage
- C7 = VP
Topographic landmarks: Sternal notch, Sternal Angle, Xyphoid tip
- T2 = Sternal notch
- T4 = Sternal angle
- T10 = Xyphoid tip
Topographic landmarks: Iliac crest, ASIS
- L4/5 = Iliac crest
- S2 = ASIS
Topographic landmarks: Greater Trochanter, Ischial Tuberosity
- Coccyx tip = Greater trochanter
- Bottom of pelvis = Ischial tuberosity
Collimation function
- Limits radiation
- Controls unwanted scatter
ID blocker
allows no exposure to film
- Place it AWAY from anatomy of interest
Effects of respiration
- Controls “voluntary” motion = reduce blurriness
- Anatomy determines when to hold breath
- Cervical = out
- Thoracic = in
- Lumbar = out
What units do Calipers measure in?
Centimeters
What material is in gonadal shielding?
Lead vinyl sheets
Flat Aluminum filters
- Evens out radiographic density
- Placement
- Between xray beam and Pt
- Over thinnest portion of intended anatomy
- Protects from exposure
Pregnancy and xray
- Delay xray if possible
- Shield fetus if xray is necessary
- 10 day rule = safest tiem to xray women of childbearing age is within 10 days after onset of menstruation
Pt Prep
- Remove clothing and put on gown
- Remove all artifacts
- Shield appropriately
- Explain procedure
- Measure Pt with calipers
- Control voluntary movment
Equipment prep
- Set Source-to-Image Distance (SID)
- 40” or 72”
- Set tube tilt (typically perpendicular to anatomy)
- Put cassette in bucky
- Collimate to part size and orientation
- Apply anatomical marker
- Add filtration (if needed, over thinnest part)
Summary of Set-up
- prep Pt and set exposure
- set SID, and tilt tube
- select film size and align to part
- positon Pt/part
- align CR—part—IR
- collimate to part
- apply anatomical marker
- apply filter (if needed)
- give breathing instructions
- make exposure and change IR
Info needed for legal xray identifiers
- Patient’s
- Number
- Name
- DOB
- Exam info
- Facility info
- Correct anatomical marker
