Radiation Safety
The Acronym ALARA
As Low As Reasonably Achievable
The Definition of Attenuation
How different tissues absorb or scatter x-rays differently
What is the Housing of the CT Machine called?
The Gantry
Name the handheld device used in Ultrasound
The Transducer
Metal
Pacemakers
Neurostimulators
Oxygen Tanks(!!)
How often does a TLD get checked for dose reports?
Quarterly (every 3 months)
The Definition and use of kVp
Definition: The primary control of the x-ray beam energy.
Use: The higher the kVp, the more penetration for thicker anatomy
What numerical scale quantifies attenuation?
Hounsfield Units
How do we reduce the layer of air between the probe and skin?
What type of energy does MRI use?
Electromagnetic Energy
How much exposure drops after you double distance from the radiation source (Inverse Square Law)
What is
The exposure drops to 1/4
Definition of mA
The number of electrons the boil off the filament, thus the number of projectile electrons. AKA The number of photons produced
What is the technology that allows CT machines to move around the track
Slip Ring Technology
What frequencies do you need for deeper anatomy, and more superficial anatomy?
Lower for deeper anatomy to penetrate, and higher for more superficial anatomy, which will also give better resolution
What cools an MRI machine and what temperature does it usually sit at?
Liquid Helium, usually resting at around 4o Kelvin
The Law of Bergonie & Tribondeau
Radiosensitivity increases with stem cells & younger tissues
(AKA Rapidly dividing cells)
Where do the high energy photons get generated, and what metal target do they hit in the x-ray tube?
Cathode, and Anode respectively
Any of:
Angiography
Trauma
Cancer Staging
Head Injuries
Large Impedance mismatches, such as tissue-air or tissue-bone interfaces, cause what?
What is the Larmor Frequency at 1.5T?
63.9 MHz.
The difference between Deterministic vs Stochastic Effects
Deterministic (Linear): Threshold, Severity increases with dose
-Skin Burns, Cataracts
Stochastic (Nonlinear): No threshold, probability increases with dose
- Cancer, Mutations
Define Bremsstrahlung X-Ray Production
When electrons decelerate upon interacting with the target anatomy's atomic nuclei, they emit x-ray
Higher Dose than plain X-ray
Artifacts (Such as metal streaking) can impact imaging
Sometimes less soft-tissue detail than MRI
What is the Piezoelectric Effect
Tiny Crystals, that convert electrical energy into sound, that then convert the returning echoes back into electrical signals
What Relaxation is Longitudinal Recovery, and which is Transverse Decay?
T1 Relaxation is Longitudinal
T2 Relaxation is Transverse