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56 Cards in this Set

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Who were the three people that played a role in the discovery of xrays? What did the do and what were the results?
Prof Godspeed discovered but didn't recognize signifigance. Wilhelm Roentgen practiced on his wife - wife suffered health problems but he won Nobel Prize.
Describe xray formation
Xrays are produced when high-energy electrons hit atoms. The electric kinetic energy is converted into 99% heat and 1% xray energy
Why can xrays penetrate objects that would reflect visible light?
xrays have a very short wavelength
In what two forms does xray radiation travel?
waves or particles
In what sort of direction does xray radiation travel?
straight line
Energy of xray radiation is proportionally inverse to the wavelength. Describe what this means.
The shorter the wavelength the stronger the xray radiation.
When xrays collide w/ the atoms that make up matter, what 4 things may occur?
1. change of direction - produce scatter
2. absorption
3. excitation - electrons pushed into a higher orbit
4. ionization - removes electron from orbit completely
Xrays can cause some substances to flouresce. What does flouresce mean and name two substances to which xrays have this effect.
Flouresce means to emit visible light. Xrays can cause this effect on calcium tungstate phosphors and rare earth phosphors (this is what xray films are made of)
How does xray radiation cause biological damage?
Excitation and ionization have detrimental effects on biological molecules
What three things are needed to produce xrays?
1. source for electrons
2. means of accelerating electrons
3. target for electrons to hit
What are the three components of the x-ray tube?
cathode, anode, and tube housing
What are the 2 types of anodes? What kinds of machines are they used in and what is the primary difference between the two?
Stationary and Rotating. Stationary has a larger target to withstand the heat and is used in smaller, less powerful units such as dental or portable machines. The rotating anode has a smaller target as the heat is dispersed by the rotation. These are used in more powerful machines as they produce more xrays. The rotating annode has a 2-stage switch, 1st stage brings rotor up to speed and the second stage shoots the exposure.
What is a focal spot?
Area on target where electrons hit, the smaller the focal spot, the greater clarity
Where are the cathode and anode on an x-ray machine?
They are in the tube housing
What is the "window" on an xray machine?
small opening where xrays exit toward patient
Define x-ray
A form of electromagnetic radiation similar to visible light but of much shorter wavelength
Define electromagnetic radiation
A method of transporting energy through space and is distinguishable by its wavelength, frequency, and energy.
What is a positive charged particle located in the nucleus of an atom called?
What is the negatively charged particle that travels around the nucleus of an atom called?
What is the neutral particle in the nucleus of an atom called?
What are photons/quantas?
synonymous terms for bundles of radiant energy
What is a negatively charged electrode called?
What is a positively charged electrode called?
What makes up the cathode in an xray machine?
Tungsten filament that heats up and releases electrons, and the focusing cup which holds the filament and focuses the electrons toward the "target".
What is in the anode of an xray machine?
The tungsten target mounted at an angle to direct the xrays down through the window.
What is a collimator?
Device on an xray tube that controls the size of the beam directed at the patient. It is made of lead shutters permanently attached below the window that block unwanted portions of the xray beam.
What is SID(FFD)?
Source Image Distance, Focal Film Distance - the distance from the xray film to the tube
The primary beam is most intense toward the anode or the cathode?
What is the heel effect?
Concept that you should put the thickest part of the body under the cathode side of the tube where the intensity of the primary bean is strongest.
What are the three controls on an xray machine?
MA, KvP, and Time
What is MA? Does it control quantity or quality?
Millamperage - controls the quantity of xrays produced. More MA = more xrays produced
What is KvP? Does it control quantity or quality?
Kilovoltage Peak - controls quality/penetration of the xrays that the patient receives
What does the "time" control on the x-ray machine control? Does this affect the quantity or the quality of xrays?
It controls the amount of time that xrays are produced. This controls the quantity of the xrays the patient receives.
What internal component of the xray machine changes one voltage into another?
What internal component of the xray machine converts AC (wall) current in to DC?
Name three types of transformers
Auto, high voltage, and low voltage
Name two types of rectifiers
half-wave and full-wave
What internal component of an xray machine compensates for variations of in-coming voltage to the autotransformer and is important in old barns?
Line voltage compensator
What three paths can x-rays take once they enter the patient?
1. Absorbed by tissue
2. Pass through tissue and hit x-ray film
3. Deflected/scattered by tissue
Scatter radiation is detrimental to what two things?
1. Radiographic image - it decreases the contrast and produces a darker than expected film (fog).
2. Restraint personnel
The degree of scatter radiation depends on what three things?
1. xray field size
2. tissue thickness
3. KvP

Increasing any of the above increases scatter radiation
Four ways/things to reduce scatter radiation
1. Lead in tabletop - absorbs xrays before they scatter
2. Lead in back of cartridge absorbs pass through
3. Collimate as sm as possible
4. Grids filter out scatter radiation before it reaches film
The x-ray only produces x-rays when it is _________.
A single massive dose of radiation is (more/less) dangerous than smaller exposure that over time could equal the massive single dose.
Legally, no one under the age of _____ may be in the x-ray room when it is energized unless directed by a physician.
18 years
2 types of damage caused by radiation
Somatic and genetic
Define somatic damage and give examples
tissue damage - cataracts, sterility, cancers (esp. of lung, bone, breast, thyroid, and leukemia)
Define genetic damage
gene mutations that may not show up for generations - often cause physical deformities
What cells are most sensitive to radiation damage - give examples
rapidly dividing cells - skin tissue, gonadal tissues, GI tract, bone marrow, lens of eye, fetal tissue
What are three sources of possible radiation exposure?
1. Primary beam
2. Scatter radiation
3. Leakage from x-ray tube housing
Three types of radiation exposure doses and their general definitions
1. Roentgen - exposure dose
2. RAD (Gray)- absorbed dose
3. REM (Seivert)- equivalent or occupational dose
What is MPD? Max allowed?
Maximum Permissible Dose - pertains to occupational radiation only.

Occupational MPD - 5 rems/yr, 1.25 rems/qtr
Three principles of radiation safety
1. Minimize time (time exposed and rotate personnel)
2. Maximize distance (between pt and self - stand upright when restraining)
3. Maximize shielding (apparel and other barriers)
Radiation safety rules:
Always wear protective gear, stay out of primary beam, rotate restraint personnel, nonessential people behind lead walls, don't rest arms on table during exposure, must wear dosimeter badges, collimate, reduce retakes
2 types of badges:
film and TLD
3 maintenance rules for protective equipment
1. hang, don't fold, protective gowns
2. gloves in vertical holders
3. annual xray to check for cracks/leaks