W1- General Principles of Imaging Flashcards
“Branch of medicine concerned with radiant energy and radioactive substances, including radioactive isotopes, and ionizing radiation, and the application of this information to prevention, diagnosis, and treatment of disease.”
Radiology
What is the recommended resource for identifying imaging indications and integrates common clinical guidelines such as Ottowa and Canadian C-Spine Rules?
American College of Radiology (ACR)
- “An x-ray film containing an image of part of a patient’s anatomy.”
- “Energy that is transmitted through space or matter.”
- “Neutral atom becomes charged by gaining or losing an electron.”
- Radiograph
- Radiation
- Ionization
What are some conventional terminologies for radiographs?
- plain film
- film
- X-ray
What are the 2 current units of measurement for radiation?
- gray
- sievert
What is the difference between soft and hard x-rays?
X-rays with high photon energies are called hard X-rays, while those with lower energy (and longer wavelength) are called soft X-rays. Due to their penetrating ability, hard X-rays are widely used to image the inside of visually opaque objects.
What are soft and hard x-rays used for respectively?
- Soft x-rays are used for treatment of superficial malignancies.
- Hard x-rays are used for diagnostic imaging.
Shorter wave length = ______ energy = ________ penetration
- higher
- greater
How does an x-ray work?
An X-ray is produced when a negatively charged electrode is heated by electricity and electrons are released, thereby producing energy. That energy is directed toward a metal plate, or anode, at high velocity and an X-ray is produced when the energy collides with the atoms in the metal plate.
What are the pros of plain film x-rays?
- Low cost
- Reliable
- Relatively good quality
- Ease of use
“A dynamic or continuous radiograph.”
Fluoroscopy
What is a pro of fluoroscopy?
Allows for real-time imaging and viewing for later.
“The combination of physical qualities of an object that determines how much radiation it absorbs from the x-ray beam.”
Radiodensity
What is the difference between radiopaque and radiolucent?
- Radiopaque = Harder to penetrate with x-rays (WHITE)
- Radiolucent = Easier to penetrate with x-rays (BLACK)
4 Shades of Gray + Metal
Order the following structures from least to most radiodensity (and their color):
- Water
- Bone
- Air
- Fat
- Air (least) = Black
- Fat = Gray-Black
- Water = Gray
- Bone = White
What are an additional 2 materials that will show up as white on imaging?
- Contrast media (bright white)
- Heavy metals (solid white)
How does thickness affect radiographs?
- Hollow = Denser and lighter on outsides.
- Thick = Denser and lighter on middle.
How do we determine patient positioning in regards to oblique images?
Which shoulder and anterior or posterior portion touching image receptor.
-Right anterior arm touching image receptor = Right Anterior Oblique
What is the decubitus position?
Body positioned on horizontal surface with horizontal beam.
Position to see Intervertebral Foramen at C, T, and L-spine?
C-Spine
-Oblique 45 degrees
T-Spine
-Lateral
L-Spine
-Lateral
Position to see Z-Joint at C, T, and L-spine?
C-Spine
-Lateral
T-Spine
-Oblique 70 degrees
L-Spine
-Oblique 45 degrees
Projections
- Minimum of ___ views at right angles.
- Commonly what 2 views of long bones?
- What also needs to be imaged with long bones?
- 2 views
- AP and lateral view
- joint above/below
What are each of the following:
- Density
- Contrast
- Detail
- Distortion
- Density = Degree of blackening.
- Contrast = Affects anatomical detail (high vs low)
- Detail = Sharpness and accuracy of structural lines.
- Distortion = Difference between actual and recorded image. (elongated/shortened)
What is an arthrography?
- Injection of contrast within the joint space.
- Distends capsule.
- Outlines internal surfaces.
- Commonly used with CT, MR, and fluoroscopy.
What is a myelography?
- Pertaining to spinal cord, dura mater, & nerve root.
- Injected in cerebrospinal fluid (subarachnoid space).
- Column of radiopaque fluid.
- May be administered with CT.
- What is a CT?
- What is the best clinical application for CT?
- What are the limitations of CT?
- Series of X-ray images taken from different angles around your body to create cross-sectional images (slices) of the bones, blood vessels and soft tissues.
- Fracture evaluation.
- Detail cannot be enhanced, difficulty with positioning, exposure.
- What is Nuclear Imaging?
- Is it used to target a specific body region or the whole body?
- Is it used for static imaging or viewing over a period of time?
- Produces images by detecting radiation from different parts of the body after a radioactive tracer material is administered. The images are recorded on computer and on film.
- Either the whole body OR specific body region.
- Can be used for either static imaging or over a period of time.
- What is MRI?
- What are some indications for MRI?
- Radiofrequency waves within a magnetic field interacting with tissues. Relies on detection of reemitted radiofrequency waves that are absorbed.
- Soft tissue trauma, internal joint derangement, tumors, stress Fx
- What is Ultrasonography?
- What are some indications for Ultrasonography?
- Is it used for bone and joint spaces?
- Image comes from reflected sound waves, tissues differentiated by acoustic quality.
- Muscle/tendon/ligament lesions, cysts, soft tissue tumor, blood flow, muscle function
- Not usually
Who is the imaging specialist and directs choice and sequence of studies?
Radiologist
Imaging Considerations. (7)
- Pathology-specific research properties
- Tissue specific sensitivities
- Structural clarity
- Radiation exposure
- Invasiveness
- Risk
- Cost
