Rad Anatomy Flashcards
Discovery of x-rays
Wilhelm Conrad Roentgen in 1895
Properties of X-rays
- Travel in straight lines at the speed of light in a coneshape
- Diverge in space from the source
- Cause certain crystals to flouresce
- Cannot be detected by human senses
- Differentail absorption
- Cannot be refracted by a lens
- Produce biological effets
Clinical Use of X-rays
- Diagnostic application as early as 1895
- Medical use and chiropractic use
- Harmful effects identified
ALARA- 1994: As Low As Reasonably Acheivable
No such thing as a SAFE dose
When to Take X-rays
New patient or existing patient with a new complaint or an Existiing patient with **no or poor response **to treatment then:
Clinical History and Examination and Evaulation
What is the working clinical differential diagnosis or assessment?
Will radiographs help clarify or impact the Diagnosis and/or Prognosis and/or treatment?
If NO-there is no clinical need for diagnostic imaging then: NO DIAGNOSTIC IMAGING PERFORMED.
If YES-There is clinical justification for diagnostic imaging then: Do the benefits of imaging outweigh the risks to the patient? Then:
** If NO- **Then: NO DIAGNOSTIC IMAGING PERFORMED.
If YES- Then: Determine imaging modality most appropriate depending on patient presentation and differential diagnosis. Then:** DIAGNOSIS IMAGING PERFORMED**
Advanced Imaging
- Computed Tomography (CT)
- Magnetic Resonance Imaging (MRI)
- Myelography (with/without CT)
- Diagnostic Ultrasound
- Nuclear Medicine
- Dual Energy X- ray Absorptiometry (DEXA)
- Mammography
Producing Radiographs
Minimal equipment:
X-ray source Image recorder (film) Subject/patient
X-ray beam travels from the source, through the subject, to the film.
Image Formation
- X-ray tube- source of electrons
- X-ray beam- focused stream of photons directed at object
- Object- beam is absorbed or passes through depending on varying densities
- Film- photons that pass through object strike the film and react with silver coating to form an image
- Image- record of photon interactions
X-ray Photons
Produced when electrons hit the target
X-ray photon interaction
X-ray photons penetrate object and are absorbed or passed through an object and strike the film
X-ray Beam
- Beam is cone-shaped from a point source
- The most central portion is called the central ray
- The more central portion of the beam diverges leess; this gives the “truest” image
- Typically, the beam will be perpendicular to the film ( Beam 2)
- To view some structures, the beam may be angled
Radiographic Image
- Black, white nand shades of gray
- It’s all relative
Differential Absorption
- Penetration dependent on density
- Denser the oblect = less penetration
- More beam striking the film = the blacker
- Less Beam striking the film (more absorption) = whiterAir = black, H2O/Muscle = gray, Bone = white
Tissue Density
- A product of the type of tissue and the thickness of that tissue
- Results in differential absorption
- Increased tissue density = whiter area on film-More tissue quantity = whiter
- Decreased tissue density = darker area on film- Less tissue quantity = darker
Anatomic Densties
Photons in= the same amount of photons hit the tissues but only some continue through the tissues.
Bone- the least photons pass through the tissue therefore, shows up as the whitest image on the film.
Muscle- moderate amount of photons pass through the tissue therefore shows up as a gray image on the film
Air- the most photons pass through unobstructed by tissue therefore shows as the blackest image on the film.
Differential Absorption 2
Black→ Air (Lungs/ Trachea/ Outside the body)
Dark Gray→Fat ( Perirenal fat/ Fascial plane)
Gray→ Water ( Muscle/ Organs)
White/Light Gray→ Bone (Bone/ Atherosclerotic plaquing)
White→ Metal ( Filings/ Markers? Ortho devices)
X-ray Photons Passed Through
- Non-defense objects - Air and Soft tissue
- Image appears blacker
- Radiolucent appearance - Darker/ nothing
X-ray Photons Absorbed
- By dense object- Metal and Bone
- Image appears whiter
- Radiopaque appearance
Radiographic Densities
- Most radiolucent = least tissue density = most blackness on film
- Most radiopaque = most tissue density = most whiteness on film
Image Terminology
RADIOLUCENT- Readily allowing x-rays to pass through the object to strike the film.
- Appears blacker on x-ray film
- Ex. Lungs (soft tissue) are more RADIOLUCENT than bone( dense hard tissue)
RADIOPAQUE- Not permitting the transmission of x-rays though the object to the film.
- Appears whiter on the x-ray film
- Ex. Metal (dense hard material) is more RADIOPAQUE than bone
Positonal Terminology
PROJECTION- Most common
- Anteroposterior/ Posteroanterior-Visual: Front to Back/ Back to Front
- Lateral-Side View
- Oblique- Angled View through the body
Projection - AP/PA
Anteroposterior / Posteroanterior (AP/PA)
-The central ray enters the patient in a:
- Front to Back (AP) or
- Back to Front (PA) direction along the horizontal plane
- Options: AP or PA
- The spine is usually radiographed in the AP projection
- Ex. AP Thoracic- Beam projected on the anterior side of patient and posterior side of patient is against the film.
Projection - Lateral
-Lateral
- The x-ray beam enters the side of the patient along a coronal plane and travels Lt to Rt or Rt to Lt through the patient t the film.
- Options: Left lateral or Right lateral
- Example: Left Lateral Lumbar named for which side of the patient is against the film
- Left Lateral = Left side against film = X-ray beam travels from right to left though the patient.
Left Lateral = Beam→Rightside →Leftside →Film
Right Lateral = Beam→Leftside→Rightside→Film
Projection-Oblique
Oblique
- The patient is postiioned oblique to the film so that the central ray passes through the patient at a 45º angle to their coronal and sagittal planes.
- Options: Right Anterior Oblique ; Right Posterior Oblique; Left Anterior Oblique; Left Posterior Oblique
- Ex. Oblique Cervicals
Left or Right
and
Anterior or Posterior
Body Postion
**Upright- **AP or PA or Lateral
**Recumbent- **Supine or Prone or Lateral
**Oblique- **Right or Left and Anterior or Posterior
**Decubitus- **Any positon in the lying posiiton