Diagnostic Imaging pt. 1

Roentgen (photon)

X-ray in the air (high energy, short wave)

Diagnostic ability from ionization

99% heat and 1% diagnostic

REM (tech dose)

Roentgen equivalent in man

REM = dosimetry

MPD

Maximal possible dose (badges)

5(N-18)

RAD (absorb Dose)

Roentgen absorbed dose in anything

Reducing heat of the anode

1.) rotate the anode (rotor)

2.) drop of oil

3.) long filament

4.) line focus principle

Primary radiation:

Electron = primary photon

Bremsstrahlung (braking)

Characteristic (collision)

Bremsstrahlung (braking)

Most photons (nucleus interaction)

Characteristic (collision)

most energy (inner shell collision)

Secondary radiation

1.) Primary photon = secondary photon

2.) scatter: compton and thompson

Compton scatter

Outer shell electron collision → energy loss

Thompson scatter (classical)

Equal energy exchange and low energy photons

Added filtration is usually

aluminum and added (plus) inherent = total 2.5mm

Anode heel effect (Attenuation)

Cathode down

anode has been weakened

Line focus principle

Increase angle target → larger focal spot → smaller effective beam

Grid ratio

height to distance between lead strips

Grid frequency

Number of strips per inch

16:1

Film base supports

emulsion with silver bromide and halide crystals

Develop →

fix → wash → dry

Red light (safe light)

seven watts preferred

Recumbant film

compresses tissues → decrease KVP

Quantum mottle

screen crystals and packets of photons

Bergionie tribondeau (radiosensitivity = rapid proliferation)

Most radiosensitive (mutate) → blood (WBC), and sperm

Least radiosensitive (death) → nerve, thyroid, ovaries

Static on film indicates

need more humidity in dark room

Developer

reduces exposed silver crystals

Fixer

removes unexposed crystals (clears and hardens)

Brown discoloration from

poor washing

old developer causes

yellow film

If film is not exposed and developed it will be

translucent

If film is exposed and developed it will be

black

Everything outside of x-ray machine is typically

LEAD

Fine details =

no crystals

Grid collects scatter to

protect from overexposure of film!

Low kVp =

high contrast = few shades, short scale

High kVp =

low contrast = lots of shades, long scale

Contrast (kVp)

Change: 15%

Controls: shades = structures

Photon: penetrability

Description: quality

Relationship: decrease kVp = increased contrast

Density (mAs → amount or number of photons)

change: 30-50%

Controls: darkness

Photon: numbers

Description: quantity

Relationship: Increase mAs = increased desnsity

15 (kVP) / 50 (mAs) rule

used to alter contrast and maintain density

if you want to increase contrast (see more structures)

increase kVp by 15% and decrease mAs by 50%

If you want to decrease contrast (see less structures)

decrease kVp by 15% and double mAs

Double distance =

4x mass

Inverse square law

FFD (distance) to mAs (density)

-double distance use 4x mass

-half distance use ¼ mass

Increased details

Distance: increased (FFD) or decreased (OFD)

Shadow: umbra (lack of shadow)

screen: small crystals

Focal spots: small (hot spots, crack the tube!)

Decreased details

Distance: Decreased (FFD), or Increased (OFD)

Shadow: penumbra (increase shadow, bad)

Screen: large crystals → rare earth blue green crystals → decent sized crystals

Focal spot: large (line focus principle → increase angle of anode → large active beam → small effective beam

Chamberlain’s Line

from hard palate to the foramen magnum (basilar invagination) (bone softening)

McGregor’s line

From hard palate to the occiput (basilar invagination)

Martin’s Basilar angle

From the nasion to the sella, to the foramen magnum (platybasia, Arnold Chiari)

Arnold Chiari → flat head that leads to basilar invagination

McRae’s Line

From anterior foramen magnum to posterior foramen magnum

Jackson’s stress lines

posterior C2 body → Posterior C7 body

Hyper C4-C5

Normal: C4-C5

Kyphosis: C5-C6

Spinolaminar line

anterior aspect of spinous processes

posterior spinal canal

Georges line

Posterior aspect of bodies

Anterior spinal canal

upper cervical → 22mm avg

Cervical: 12mm minimum

Lumbar: 15mm minmum

Eisenstein’s (canal body ratio)

spinal canal should be width of pedicle → width of pedicle is evaluat4ed by vertebral body size

2:1 = good (fit 2 pedicles in 1 body)

4:1 = bad

McNab’s line

Facet imbrication, degeneration

drawn on inferior endplate of the superior vertebra and superior facet of the inferior vertebra

Van Akkerveeken’s

patient leans back into hyperextension to load facet

Prediction

Hadley’s S curve

Alignment → A-P and oblique

Ferguson’s line

lumbar gravity line

Normal intersects with anterior 1/3 of sacral base

Lumbosacral angle

<35-45

aka ferguson’s angle

Anterior sacrum

Hyperlordosis, increased shear

anterior weight bearing

Lumbosacral disc

<10-15

Posterior sacrum (line)

hypolordosis

increased weight on sacrum

posterior weight bearing

Salter harris type 1

fracture through the growth plate

Salter Harris type 2

fracture through growth plate and metaphysis

Salter harris type 3

Fracture through growth plate and epiphysis

Salter harris type IV

Oblique fx through metaphysis and epiphysis

Salter harris type 5

compression injury (crush)

Scoliosis

1.) most often a right lateral deviation in the spine. most commonly seen in thoracolumbar region of adolescent girls

2.) Adams test is used to determine whether it is structural (progresses until maturation) or functional

3.) risser’s sign or P-A wrist (maturity)

4.) multifidi spasm causes rotation

Protocol for care of scoliosis

1.) 0-20 degrees = adjust

2.) 20-40 degrees = bracing

3.) >40 degrees = surgery

4.) >50 causes cardiopulmonary compromise

Lovett + (rotatory)

spinous into the concavity

(asymptomatic scoliosis)

Lovett - (Simple)

symptomatic

multifidi contractions on side of spinous

Kohler’s

acetabular protrusio (walstrum’s teardrop)

bilateral (pagets and RA)

unilateral (infection and OA)

Klein’s line

SCFE

Skinners line

paget’s → bone softening or osteomalacia (rickets in children)

Femoral angle (aka Mikulicz’s)

coxa vara = <120 degrees

Coxa valgus = >130 degrees

Boehler’s angle

<20 degrees = calcaneal fracture

>20-40 degrees is normal

Types of spondylolisthesis

1.) Dysplastic (congenital)

2.) isthmic (pars alteration)

3.) degenerative (L4 more common)

4.) traumatic (fracture other than pars)

5.) pathological (associated with disease)

6.) iatrogenic (treatment induced)

7.) pending (developing stress fx, MRI needed)

Treatment of spondylolisthesis

Grade 1: adjust

Grade 2: adjust

Grade 3: maybe

Grade IV: no

Meyerding’s

grading method for spondylolisthesis

Ullmann’s

used to diagnose L5 spondy

Georges line is for every other level

Spondyloptosis

Not a grade, its a tilt

Inverted napolean hat / Brailsford’s bow

contraindication to adjustment

Most common cause of spondylolisthesis

trauma

most common level of spondylolisthesis

L5

Contraindicated adjustment for spondylolisthesis

prone

Preferred adjustment for spondylolisthesis

supine knee chest

Most common level of degenerative spondy

L4

Most common type of spondy

isthmic

most common level of traumatic spondy

L5

retro pharyngeal

less than 7mm

Retro laryngeal

<14 mm

Retro tracheal

<22mm

ADI

<5mm in child

<3mm in adult

Coracoclavicular: Normal

4-5mm

Coracoclavicular: sprain

6-8mm

Coracoclavicular: separation

>9mm

Glenohumeral normal

4mm

Glenohumeral DJD, CPPD

>5mm post dislocation

Acromiohumeral: normal

7-11mm

Cervical obliques: RAO = LPO

Right IVF visible

Cervical Obliques: LAO=RPO

Left IVF visible

Lumbar obliques: RAO=LPO

left pars

Lumbar obliques: LAO=RPO

right pars