Exam 1 Flashcards
What is radiation?
the energy that is transmitted through space or matter `
What are the 4 types of radiation?
Electromagnetic radiation (EMR)
Particle radiation
Natural radiation
Man made radiation
T/F
Electromagentic energy is primary with the production of x-ray
True
How is EMR measured?
In eV (electron volts)
What is keV?
1000 eV = 1 kiloelectron volts
How is frequency of EMR measured?
In Hz
How is wavelength of EMR measured?
M (meters)
T/F
X-ray has a low frequency and a long wave
False,
Low frequency, short wave. High energy
How fast does EMR travel?
Speed of light. Has no mass and travels in bundles called phontons or quanta. Travel in waveforms with varying wavelengths and frequencies
How is EMR divided?
Ionizing and non ionizing
What is ionizing radiation?
Enough radiation to knockout an electron. Causes imbalance.
What is the wavelength and frequency of ionizing radiation?
Short wavelength, high frequency. Thus high frequency (e.g. gamma rays, xrays)
What is nonionizing radiation?
Does not have the energy to remove electrons
What is the wavelength and frequency of ionizing radiation?
Low frequency, long wavelength = low energy.
What are some examples of nonionizing radiation?
Visible light, infrared light, tv, UV light, radio, microwaves, heat
What is particle radiation?
Not EMR but has ionizing capabilities. It’s the decay of a radioactive atom’s nucleus.
What particles are implicated in particle radiation?
Alpha and Beta particles, less penetrating than x-ray
T/F
Particle radiation is less harmful altogether than EMR?
False,
More harmful when inhaled
What is the method/system for measuring ionizing radiation?
Dosimetery, performed by a dosimeter.
What are the 4 SI units for dosimetry?
Roentgen (R) or coulombs/kg. Measures ionization in air.
Radiation absorbed dose (rad) or grey (Gy)
Radiation equivalent man (rem) or sievert (sv)
Curie (Ci) or Becquerel
What does rad or gy measure?
Measures the amount of radiation absorbed in tissue (100 rads = 1 Gy).
What is a milirad?
1/1000th of a rad
What are milirads used to measure?
Biological effects of radiation to specific organs or tissues
What is rem or Sv used for?
Radiation detection in reporting exposure
What is a milirem?
1/1000th of a rem (mrem)
What does a dosimeter look like for workers, and what does it specifically measure?
A film badge, worn on clothing. Measures for biological effects from delayed exposure
T/F
Curie (Ci) or Becquerel is one of the primary SI unit used for dosimetery in regrad to x-ray
False,
Not used for x-ray
How much ionizing radiation do people receive on average/year?
360 mrads
How much of average yearly exposure to ionizing radiation is represented by natural (background) radiation?
82%
What is cosmic radiation?
Natural radiation from sun and stars, increases at higher altitude, increases the farther the latitude from the equator
What is terrestrial radiation?
Natural radiation from soil, rocks, mountains (bricks, cement, wallboard, radon gas from decay of uranium.
What is internal radiation?
Nuclides (natural radioactive substances), found in living tissue, also ingested in food and water.
What percent of yearly dose dose man-made radiation account for?
18%
What is the largest source of man-made radiation exposure?
X-ray procedures
What are some ancillary sources of man-made radiation?
Nuclear medicine, Consumer products, nuclear testing, nuclear reactors
T/F
Diagnostic x-rays levels are far below what would cause acute effects, long term effects of low levels are controversial
True
What are some contraversial conditions that are argued to come from low levels of radiation exposure?
Leukemia (from fetal dose) and malignancies years after exposure. Mutation from gonad dose
What is linear theory?
The idea that any amount of x-ray exposure is harmful
What is the whole body dose?
Exposure to the entire body, more detrimental than exposure to a specific part
What is the whole body dose?
Exposure to the entire body, more detrimental than exposure to a specific part
What is the skin entrance dose?
Exposure to the skin, always higher than the structures below the skin, the deeper the part the lesser the exposure due to absorption
What is the somatic dose?
Exposure that causes tissue damage. NON reproductive damage. Target molecule for damage is DNA
What are earliest effects?
1st: Erythema
2nd: Hair loss
What is the genetic dose?
Exposure potentially causing damage to future generations of the exposed individual
What is damaged in genetic dose?
Low level exposure (including diagnostic exposure) to gonads. Reproductive tract damage, leukemia, mutations.
What is the fetal dose?
Fetal exposure of up to 10 rad is not expected to have any effect on the newborn
How do you calculate fetal dose?
Your local radiation physicist
What are stochastic somatic effects?
Probability of a harmful effect increases as the dose increases. Long term effects such as cataracts and cancer.
What are deterministic somatic effects?
Non stochastic effects. Known effects increase with dose. Short term effects: erythema, infertility, blood forming damage, cataracts. Has a threshold at which effects are predictable
What is protraction?
If exposed at a low level continuously, effects are reduced (used in radiotherapy, radioactive implants)
What is fractionation?
Non continuous exposure to high doses reduces effects (used in radiotherapy)
What is radiation hormesis?
The apparent beneficial effects of radiation. Small doses of radiation may reduce infections and fatal malignancies, and prolong life (perhaps an immune system booster).
What is ARS?
Acute radiation syndrome (or sickness): The various effects from large doses of radiation
What are the three effects of ARS?
1st effect: Hematological syndrome
2nd effect: Gastrointestinal syndrome
3rd effect: Central nervous system syndrome = chemoresistant - fatal
What are the 4 stages of ARS?
Prodromal stage: Initial symptoms
Latent stage: Improvement of symptoms
Manifest stage: Return of symptoms worse than before
Healing or death: Either you recover or die
What is the LD 50/60?
An acute full body exposure that would kill off 50% of the people exposed within 60 days.
What is the LD 50/30?
Lethal dose
What is the LD 50/60 for humans?
350 rads without medical intervention
What is the LD 50/30 for humans?
300 rads
Who discovered x-ray?
Wilhelm Roentgen in 1895 from Germany. X-ray was first called “Roentgen ray”.
What was the 1st x-ray image?
Bertha’s hand
When was x-ray first used in chiropractic?
1910
T/F
Distance reduces the intesity of x-ray
True
What does x-ray penetrate, and what is it absorbed by?
Penetrates matter but is absorbed by dense materials (cement, lead, compact bone)
What is x-ray scatter?
Secondary rays from objects struck by x-ray. Detrimental to film and patient
How does x-ray travel?
In diverging straight lines from it’s source
What is a big cause of image distortion considering how x-ray travels?
Divergence
What determines if an area on the film is white?
When the x-ray is absorbed in front of the film
When does the film turn dark?
When exposed
T/F
X-ray is not stored in matter and will not make it radioactive
True
T/F
X-ray cannot be focused, reflected, or refracted
True
Can human senses detect x-ray?
No
What 3 things are needed to create an x-ray?
A source of electrons
A way to accelerate them at high speed
A hard surface (a way to stop them)
How is leakage of radiation controlled in the tube housing?
The housing is lined with Lead
What is the radiation amount from the tube housing?
100mRad/hour @ 1 meter
What role does oil in the tube housing play?
Replaces air, dissipates heat (thermal insulator)
What does the window or port of the tube housing do?
Allows intended rays to exit
What is the tube arm?
Holds the tube housing in place
What is the tube stand?
Holds the tube arm and allow it to move the tube vertically
What is the tube track?
Allows the tube to move horizontally. C-arm has no track
What contains the functional parts of tube?
Glass tube (glass envelope)
What are the rays exiting the window of the glass tube called?
Useful beam
What is the CR
Central ray. All other rays angle away from CR. Divergence decreases the more central the beam is.
What is the cathode?
Negative electrode. Electron producer, focuser, and propeller.
What is the cathode?
Negative electrode. Electron producer, focuser, and propeller. Contains filament and focusing cup
What controls the # of x-rays?
The # of electrons
Most cathode units have a small and large filament (dual focus tube) what does each filament produce?
Small filament: produces clearer images
Large filament: Less clear image, handles more heat
What is the anode?
Positive electrode. Photon producer
What are the 3 functions of the anode?
Stops electrons thus produces x-rays.
Dissipates heat
Conducts electricity
What are the 3 parts of the anode?
Target: where high speed electrons are propelled to
Stem
Rotator
What is the “focal spot”
Areas where x-rays are emitted
What are the actual and focused effective focal spots?
Actual: Where electrons strike causing x-rays
Effective: Where photons exist
Large spots produce more_________
Penumbra: Unclear borders produced by Large spots
Small spots produce more __________
Umbra: Clear borders
What are the 2 types of anodes?
Stationary and rotating anodes
What is the sound you hear before you are exposed?
Rotor rotating the rotating anode
What is the line focus principle?
Larger angles/larger focal spots = image less clear
Smaller angles/smaller effect focal spots = images are clearer
What is the anode heel effect?
Bottom of the bevel decreasing beam intensity
On what side of the tube is the beam less intense?
Anode
Anode should be near thinner parts and cathode near thicker parts, therefore…
Anode up and cathode down for full spine
When electrons collide with the target, x-rays are produced in two ways. What is the first and major way?
Bremsstrahlung radiation: Interaction of an incoming electron with target nucleus. Incoming electron passes close to the nucleus, direction of electron is changed, causes electron to lose energy, lost energy is converted to x-ray. Makes up the majority (85%) of the x-ray beam.
What is the less common secondary way x-rays are produced with electron collision?
Characteristic radiation: An interaction of an incoming electron with a target electron. The incoming electron collides with a K shell target electron knocking it out of its orbit
What does filtration do?
Attenuates (reduces) beam intensity. Helps eliminate weaker (soft) rays, which increase organ dose and skin entrance. Mostly measured in Al thickness or Al equivalency
Allows stronger (hard rays) to get through (harden the beam)
