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
Upright Positions
- Usually AP/ PA
- The patient is standing upright for the x-ray examination
- This allows for evaluation of postural information
- Many chiropractors utilize upright lumbar/pelvis films to evaluate for leg length inequalities
Recumbent Postions
- Usually Supine or Prone
- The patient is lying down for the x-ray examination
- No reliable evaluation of postural elements can be obtained from recumbent views ie. compression etc.
- The positoning is useful when the patient is in a lot of pain or when the patient is very large
Minimum Diagnostic Series- What X-rays to Take
- Standard views required to evaluate an area
- Minimal 2 views perpendicular to each other
- Some variation by facility or circumstance
- Add optional views depending on case
- Must take at least 2 views
- Projections oriented 90º to one another
- View 3-D object in 2-D
- Some body parts require more than 2 views for a minimal study
- Supplemental views outside the minimal series are used to better visualize specific structures
Minimal Diagnostics-Cervical Spine
Cervical Spine
Minimum Series:
- AP
- Lateral
- AP Open Mouth (Odontoid)
Supplemental Views:
- Obliques
- Flexion/Extension
- Lateral Bending APOM
- Pillars
Alternative Views:
- Swimmer’s
- Fuchs/Judd
Minimal Diagnostics- Thoracic Spine
Thoracic Spine:
- AP
- Lateral
Supplemental Views:
- Swimmer’s
Minimal Diagnostics- Lumbar Spine
Minimum Series:
- AP/PA
- Lateral
Supplemental Views:
- Axial AP/PA LS Spot
- Obliques
- Lateral L5/S1 Spot
- Flex/Extension
- Traction/ Compression
- Scanogram
Minimal Diagnostics- AP Full Spine
( For Scoliosis evaluation)
Minimum Series:
- AP Projection (initial exam)
- PA Projection (for subsequent exams)
Supplemental Views:
- Sectional Lateral
- APOM
Minimum Diagnostics- Sacrum
Minimum Series:
- AP
- Lateral
Minimum Diagnostics-Coccyx
Minimum Series:
- AP
- Lateral
Choice of Positioning
-In choosing what films to take and what projections, postions, views and methods to utilize, it is important to:
- Place the structures that you wish to visualize closest to the film
- Start with standard (minimal diagnostic) series
-Choices may be influenced by:
- What particular structures you wish t visualize
- The patient’s clinical presentation
- The differential diagnoses under consideration
- The patient’s size
- Patient protection (e.g., female pelvis)
Film Markers
- Informational Markers = made of metal taken with the x-rays indicate Lt or Rt images
- Mitchell Marker
- BBs in the Markers which indicate upright or recumbent body positioning in images
- Name Blockers = Patient’s and Dr.’s name
- Identification Markers – Type of Study
-Identification Markers– Clinic & Tech (where and who took the images)
Informational Markers
- Provide infrmation about the patient
- Provide information about the doctor and/ or facility
- Identifies side of patient or patient positioning
Mitchel Markers
- Metal markers
- Taped to film cassette (prior to exposure) L or R
- Label anatomical side of patient
- AP/PA and extremeties
- Label side of patient closest to film
- Laterals and Obliques
- Usually contain BBS
- BBS in center of bubble indicate a recumbent body position
- BBS are gravity dependent
- Concave surface- BBs in middle= recumbent; BBs on the bottom = upright or other
Markers
Markers may also identify:
- Type of study
- Patient positioning
- Technologist
- Facility
- Weight bearing
- Traction Position etc.
- Position of objective ER, MR, LR etc.
- Cervical Spine= Always AP view upright
Warning!
As a general rule:
Without a marker, you cannot identify which side of the patient is the left and which is the right!
Name Blocker
Usually on a sticker or exposed on the film will contain:
- Patients Name
- Patients Gender
- Patients Age
- Doctors Name
- Facility where films were taken
- Date of study
Viewing a Radiograph
-Composite shadowgram
- Profiles/Shadows/Outlines are detailed
- Structures add contrasting densities
- Superimposition and object orientation confuse the picture
- Think 3-D (Identify the object not the person being x-ray’d
- What is in profile and what is seen on end
The Whole Picture
-An X-ray beam penetrates the entire object through which it passes, creating and image of all the various aspects of that object and all objects that lie in the path of the beam.
Composite Shadowgram
- Squire explains radiographic images as a “composite shadowgram” that represent the sum of the densities interposed between the beam source and the film.
- Final image involves superimposition of objects and orientation of objects
Projection
- The beam travels some distance from the object it strikes until it reaches the film. The orientation of the beam-object-film will affect the location of shadows.
- If you face the sun your shadow will be behind you. If the sun is behind you, your shadow is in front of you.
Beam 1 Beam 2 Beam 3
A
B
C
Film__________________
A B c All c B A <—- more to edge of film
Image 3 Image 2 Image 1
Superimpositon
- Radiographic images of objects that lie in the same path of the x-ray beam will be superimposed in each other (on top of each other)
- The radiograph image is a representation of all the densities superimposed on one another. It is not possible to distinguish each density separate from the other densities
- The superimposition of objects is affected by their anatomical relationships.
- Superimposition is not affected by the order (AP vs PA) that the beam strikes the objects.
- Projection and superimposition are affected by the objects relationships to the central ray
- The central ray is simply the most central portion of the beam
- Ex. if the center beam, of the cone shaped beam, travels through the joint space then the true measure of the joint space will reflect on the film.
- If the angled part of the beam, of the cone shaped beam, travels through the joint space then a false measurement of the joint space will reflect on the film.
Distortion
- If the central part of the beam is angled to the object then the image will appear larger on the film than the actual size of the object.
- A “skycam view” = “Bird’s eye view” may make the image inidentifiable
Magnification
- If an object is closer to the source of the beam it will appear as a larger image on the film (Object Image Distance, OID)
- Transversly: if the same size object is further from the source of the beam it will appear as a smaller image on the film
Object size = Image size x Corection Factor
O= I x CF
CF = D (total distance of beam to film) x d (object distance from film) / D (total distance of beam to film)
Collimation
- Shutters (barn door) block periperal protions of beam ie narrows beam before it strikes image to reduce patient exposure
- Limits area exposed to beam; uses most central protion of beam.
- Light indicates the area the beam will strike directly
- Limits size of x-ray beam feild
- Use smallest area possible for good x-ray
- Decreases scatter radiation
- Decreases patient dose
- Achieves better detail
- Tube light simulates x-ray beam
- In Oregon-must show collimation on 3 sides
Bone: General Properties and Architecture
Compact Bone
-Compact Bone = Cortex
- Outer shell of bone
- Encloses the medullary bone
- Covered by periosteum
- Homogenous density of x-ray
Spongy / Cancellous Bone
- Spongy Bone = Cancellous Bone
- The network of trabeculae in the medullary portion of the bone
Periosteum
- The fibrous outer layer of bone
- Responsible for membranous bone formation, attachment of tendons and ligaments, and contains vascular supplies for the bone
- Not present on suraface of intra-articular bone (follows synovial membrane with the capsule)
- Normal periosteum not distinguishable on a radiograph
Categories of Bones
-Flat Bones: ribs, sternum scapula, cranium. iliac wing
-Short Bones/ Square Bones: carpals, tarsals, vertebrae
-Sesamoid Bones: embedded in tendons
-Long /Tubular Bones: femur, humerous, etc.
Long/Tubular Bones
-Epiphysis: The articular end of the bone; separarted from the rest of the bone by the physis (growth plate)
-Metaphysis: The tapering portion between the physis and the shaft (diaphysis); the site of growth and greatest metabolic activity
-Diaphysis: The shaft of bone; medullary cavity filled with red marrow
Apophyses
- Tuberosities, Tubercles, Trochanters, Processes, Spines/;Spinouses, etc.
- Osseous projections from the general shape of the bone which develop to support and in response to the forces at major ligament and tendon insertions and at articular surfaces
-Apophysis: Lateral superior of the femur ie greater trochantor
-Epiphysis: Medial superior of the femur ie. Head and Medial epicondyle
-Cortex: ie, denser part of shaft of femur
-Diaphysis: ie. shaft of femur
- Metaphysis: ie. superior part of femur anterior of head and superior to lthe distal end ie. the epicondyles
- Medullary Cavity: The core of the bone
- Trabecular Bone: the “spongy” part of boneat proximal and distal parts of bone.
Reading Films
- Differentiate normal from abnormal
- Localize abnormality
- Describe abnormality
- List perinent postives/pertinent negatives
- Give an impression of clinical significance
Radiographic Evaluation
-Have a systematic approach
- Have a system
- Use the system every time
- Be thorough
