Review Flashcards
Exists a threshold dose; deterministic radiation
Non-stochastic
Occurs randomly; probabilistic radiation
Stochastic
Divergence of x-ray as it travels
Attenuation
-Effected by SAD (Scatter, Absorption, Distance)
Used to describe the amount of energy deposited in tissue (absorbed dose)
RAD (Radiation Absorbed Dose)
Dose equivalence; unit of reporting occupational exposure
REM (Radiation Equivalent Man)
Inverse Square Law
I1/I2 = D2^2/D1^2
Site of x-ray production
Anode
Source of electrons
Cathode
If image is too dark (excess density)
Overexposure
If image is too light (insufficient density)
Underexposure
Short scale contrast
Overall image: very black and white
Number of grays: few
Contrast: high
Long scale contrast
Overall image: very gray
Number of grays: many
Contrast: low
Majority of the beam formation
Bremsstrahlung (Brems): < 69.5 kV –> 100% Brems
Leads to development of characteristic radiation
Photoelectric effect: > 69.5 kV –> 10-15%
Decides the energy/quality of the beam
kVp; controls the radiographic density
e.g. high kVp means less photon absorption and more shades of gray
Decides beam quantity
mA
Casting effects on mAs
Plaster: 2x (dry); 3x (wet)
Fiberglass: 40% (dry); 60% (wet)
Radiosensitive cells
Skin basal cells, blood cells, intestinal crypt cells, reproductive cells
Radioresistant cells
Brain cells, muscle cells, nerve cells
5 Steps of Radiographic Interpretation
- Quality
- Soft Tissue
- Bone & Bone Density
- Joints & Joint Spaces
- Biomechanical Evaluation
Types of accessory naviculars
Type 1: Os Tibiale Externum; sesamoid within tibialis posterior tendon
Type 2: Pre-hallux; articulates with the navicular
Type 3: Cornuate/Gorilloid navicular; fused with the navicular
Teardrop sign of ankle
Due to traumatic hemarthrosis of ankle joint; see outpocketing of ankle capsule on lateral projection
Sullivan’s Sign
Splaying of digits due to neuroma formation
