Introduction Flashcards
What are 2 of the main properties of x-rays?
They diverge in space from the source and have differential absorption.
What does ALARA stand for?
As Low As Reasonably Achievable
There is no safe dose
What is the path of the x-ray beam?
Travels from the source, through the subject, to the film.
What is the central portion of the x-ray beam called?
The central ray.
It diverges less and gives the truest image.
What does penetration of the beam depend on?
Density.
Denser object = less penetration.
More beam striking film = blacker.
Less beam striking film = whiter.
Radiolucent:
Least tissue density; most blackness on film.
(Readily allowing x-rays to pass through the object to strike the film).
Ex: lungs are more radiolucent than bone.
Radiopaque:
Most tissue density; most whiteness on film.
(Not permitting the transmission of x-rays through the object to the film).
Ex: Metal is more radiopaque than bone.
How would you abbreviate the central ray entering the patient front to back along a horizontal plane?
AP
How would you abbreviate the central ray entering the patient back to front along a horizontal plane?
PA
In what way is the spine usually radiographed? (AP/PA)
AP
What does recumbent mean?
laying down
In a lateral projection, which side of the patient is in the name?
The side of the patient that’s closest to the film.
In what plane is the beam for a lateral projection?
Coronal
How do you position the patient for an oblique projection?
So that the central beam passes through the patient at a 45 degree angle to their coronal and sagittal planes.
What are the 4 types of body positioning?
Upright (AP/PA or lateral).
Recumbent (supine or prone or lateral).
Oblique (right or left and anterior or posterior).
Decubitus.
How is the upright position advantageous?
It allows for postural information and/or evaluation for leg length inequalities.
When would recumbent positioning be useful?
When the patient is in a lot of pain or when the patient is very large.
What is the minimal # of standard views required to evaluate an area?
2 views minimum (perpendicular to each other).
T/F: Some body parts require more than 2 views for a minimal study.
True
When choosing positioning it is important to:
Place the structures that you wish to visualize closest to the film.
Start with the standard (minimal diagnostic) series.
What are the 5 things your positioning choices may be influenced by?
What particular structures you wish to visualize.
The patient’s clinical presentation.
The differential diagnoses under consideration.
The patient’s size.
Patient protection (ex: female pelvis).
What do Mitchell Markers label?
Anatomical side of patient (AP/PA and extremities)
or
Side of patient closest to film (laterals and obliques).
T/F: As a general rule, without a marker, you cannot identify which side of the patient is the left or right.
True. (There are a few exceptions).
T/F: Superimposition is affected by the order (AP vs PA) that the beam strikes the objects.
False.
Superimposition is not affected by the order that the beam strikes the objects.
What has an affect on superimposition?
The anatomical relationships of objects.
The objects relationship to the central ray.
How do you magnify an image?
Move the object further from the film.
The further the beam has to travel to reach the film after striking the object, the more it will be magnified.
(OID = Object Image Difference)
Describe collimation:
Shutters (barn door) that blocks peripheral portions of the beam.
Limits area exposed to beam (uses most central portion of beam).
Helps achieve better detail.
What do the ABC’S of evaluation stand for?
Alignment
Bone
Cartilage
Soft Tissues
Can normal cartilage be visualized on plain film?
No. It is represented by the space that it occupies.
