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Physics
Final
| Question | Answer |
|---|---|
| X-rays are a form of electromagnetic energy (ex: radio waves, light waves, etc.) | electromagnetic energy |
| What are the four properties of photons? | frequency, velocity, wavelength and amplitude |
| Of the four properties of photons, which one is constant? | velocity |
| Chemical compound is _______ | one type of molecule |
| A branch of physics where you study objects in rest and objects in motion | mechanical physics |
| A bundle of energy in a an x-ray is known as a _____ | photon |
| The rate of rise and fall of a sine wave or the number of cycles or wavelengths of a simple harmonic motion per unit of time (Hz) | frequency |
| 1/60 of a second in the US or also known as one cycle per second | Hertz |
| Measures amperage | ammeter |
| measures the voltage in a line | volt meter |
| radiation that is produced by rebounding electrons that are landing on other areas of the target (not on the actual focal point), each time they interact with parts of the anode they produce radiation | extrafocal radiation |
| the product of absorption and scatter | attenuation |
| the different degrees by which different tissues will absorb x-rays photons results in varying contrast and density | differential absorption |
| occur every 3.14 inches from dirty 1 inch transport rollers, occur perpendicular to film travel | Pi lines |
| scratches parallel with film travel | Guide shoe mark |
| What cause a light leak resulting in high optical density (usually in a streaking fashion) on the film? | leak in film storage and exposes film |
| Remove an electron from the atom, atom has become ionized; the removed electron and remainder atom form an ion pair, electron is negative so the atom that lost electron is positive | ionization |
| coil of wire | solenoid |
| hook up electricity and vary the electrical voltage and make an electromagnet we can vary its intensity by how much current is running through the wire | electromagnet |
| What are the three parts of an x-ray imaging system? | operating console, high voltage generator and the x-ray tube |
| having a whole bunch of electrons being boiled off the filament and they essentially create a negative charge since they clump together into a cloud (little bitty space) | space charge |
| The principle by which if we angle the anode we end up with a smaller effective focal spot allowing us to keep recorded detail while increasing the amount of area for heat on a focal spot by angling we can still have a small focspt w/ large heat composite | line focus principle |
| The quantity of photons, the exposure | x-ray intensity |
| If increase the SID the X-rays travel in a straight line isotropically greater area for x-rays to so as the SID is larger can beside the film | affects of increasing the SID |
| fluctuation of energy from zero to peak (or trough) and back down to zero | voltage ripple |
| single phase generator | 100% |
| 3 phase 6 pulse | 13% (set of three start times with x-ray beam always on) |
| 3 phase 12 pulse | 4% |
| high frequency generators | less than 1% |
| Generators and Percentages: how do they affect quantity and quality and power rating | high voltage ripples have lower quantity and quality of X-rays being produced and a lower power rating |
| What does ALARA stand for? | As Low As Reasonably Achievable |
| Something that should not be on the image | artifact |
| What are electrical energy, heat, potential energy and kinetic energy examples of? | energy |
| What are ice and steam examples of? | matter |
| What are some units of measurement? | energy, power-watt, work, electricity, etc. |
| What are the systems of measurement? | British, SI, MKS, and CGS |
| British | foot, pound, second |
| SI | meter, kilogram, second (what the rest of the world uses) |
| MKS | meters, kilograms, second |
| CGS | centimeters, grams, seconds |
| The basic qualities in mechanics are _____ _____ and _____ | mass, length, time |
| This is going to be two or more of the base qualities like force or momentum | derived quantity |
| Who was the first person to describe the element of being composed of identical atoms? | Dalton |
| Who created the model of the atom we still use today? | Bohr |
| Who conducted experiments in 1911 that determined that the atom had a nucleus with an electron cloud? | Rutherford |
| The number of protons associated with an element determines the ___ | Chemical Element |
| What is the symbol for the number of protons? | Z number |
| What determines the binding energy? | the orbital shell level of the electron (Inner shell k, l, m,n) |
| If an element has an atomic mass of 95 and an atomic number of 40, what is the number of neutrons? | Atomic Mass - Atomic Number = Number of Neutrons |
| In a normal state, the electrical charge of an atom is? | zero or neutral |
| What is the innermost shell called? | K shell |
| Same number of protons as another but a different number of neutrons | isotope |
| identical atom that exists at different energy states | isomer |
| What is the smallest quantity of electromagnetic energy? | photon |
| What is the wave equation? | C = frequency * wavelength |
| The energy of a photon is directly related to _____ | frequency |
| Photons interact with matter that has wavelengths _____ their own wavelengths | similar, equal in size |
| As photon energy increases, energy ____ and the wavelength of the photon _____ | Increases, decreases |
| What would the theory of relativity be useful for in radiology? | E=mc^2 can actually be used to calculate the mass equivalent of an x-ray photon |
| like charges _____, unlike charges _____ | repel, attract |
| electric potential is measured in ____ | volts |
| how does electrification occur | movement of electrons |
| Charges concentrate where on the surface of an electrified object | sharpest curvature |
| electrostatic force relationship to distance and product of charges | inversely related to distance and directly related to the product of the charges |
| example of a direct current | battery |
| example of an indirect current | generator |
| How do we change from an direct to indirect? | Through the use of rectification or a commutator ring in an electric generator |
| how many rectifiers are needed to completely invert the negative side of the sine wave? | four rectifiers |
| the electrical component that works through self-induction | transformer |
| Series circuit laws regarding resistance | Rt=R1+R2+R3 |
| Parallel circuit regarding current | It=I1+I2+I3 |
| Ohm's law | V = IR |
| electric current and relationship to magnetism | perpendicular to path of the current |
| a charged particle in motion will create a ______ | magnetic field |
| electron rotation on their axis is called | electron spin |
| magnetic force relationship to field strength and distance | the magnetic force is proportional to the product of the field strengths divided by the square of the distance between them |
| the degree to which a material can be magnetized | magnetic susceptibility |
| permeability | is the measure of the ability of a material to support the formation of a magnetic field within itself. In other words, it is the degree of magnetization that a material obtains in response to an applied magnetic field |
| what did faraday's experiment prove? | a current could be induced by a magnetic field if that field is changing |
| how do you make an electromagnet with a coil of wire? | solenoid coil of wire and then turn electricity on to create a current through the wire then as we change that current we can change how strong a magnet we have |
| The operating console contains circuits that are _____ voltage | low |
| What is the purpose of a transformer? | convert electric potential into high or low intensities moving it up or down |
| Which has more windings on the primary side, step up or step down transformer? | step down |
| how much does a step up transformer change the voltage? | increase voltage, amperage drops/voltage drops, amperage increases |
| What are the two types of induction? | self and mutual |
| What does step up and down transformers use? | mutual induction |
| What does the autotransformer use (one winding)? | self induction |
| Why do we use transformers? | change our electrical potential |
| What type of current is needed for transformers? | alternating |
| Where is the autotransformer located in a circuit? | at the beginning of the circuit, just trying to change the voltage a little bit (minor changes) |
| Where is the step up transformer located? | between the secondary and primary, stepping up from volt to kilovolt |
| Where is the step down transformer located? | filament circuit, creates the electrons that will be boiled off |
| What is the purpose of the line voltage compensator? | minor adjustments to line voltage coming in |
| What section provides electrons for the tube current? | filament circuit |
| no rectification | 60 pulses per second |
| 1/2 wave rectification | 60 pulses per second |
| full wave | 120 pulses per second |
| 3 phase | 360 pulses per second |
| advantage of higher up generators | the higher up you go the better quality of x-rays you have |
| disadvantage of higher up generators | the higher up you go the more expensive it is and the single phase has more patient dose with a lot more x-rays being needed |
| what happens to waveform between primary and secondary sides | the waveform changes in amplitude |
| is the operating condole a high or low voltage components | low |
| What is inside the glass envelope? | rotor (spins) |
| What is outside the glass envelope? | stators (windings that we pass electricity through in a progressional pattern) |
| What is the filament made of? | Tungsten |
| What do electrons interact with? | outer and inner shell electrons at the target |
| where are the x-rays made? | at the focal spot |
| which direction do electrons flow in the x-ray tube | cathode to anode |
| what malfunction results from tungsten coating the incise of the tube? | arching: electrons get stuck to the side of the glass envelope |
| dual focus tubes have how many filaments? | two |
| how does an anode rotate? | induction motor, magnetic field that is trying to align with constantly |
| Radiographic rating chart is used for what | maximum exposure times for the tube |
| what causes anode cracking | single excess exposure |
| true/false: kVp controls the number of x-rays emitted at the filament | false; kVp will increase the efficiency of X-ray production |
| most of the ____ energy of the projectile electrons is converted to ____ | kinetic, heat |
| How does an x-ray tube primarily cost? | radiation |
| discrete | characteristic |
| continuous | bremstraulung |
| maximum energy of a continuous energy spectrum? | maximum kV set at the operating console maximum energy point of the energy spectrum |
| quantity | amplitude |
| quality | position |
| Half value layer is a measurement of beam quality | HVL |
| As you increase your kVp there will be a shift to the right, x-ray production becomes more efficient so we will have higher quantity of x-rays at the higher kV's, this is why we reduce mAs | 15% |
| If filtration increases | reduce amplitude and shift to right (take out photons) |
| If kVp increases | increase amplitude and shift to right (increases overall energy of the beam) |
| If mAs increases | increases amplitude only (direct proportion) |
| cause more efficient X-ray production | kvp |
| largest source of manmade ionizing radiation exposure to the public | medical radiation |
| year of X-ray discovery | 1895 |
| who discovered xray | whillhelm rotegen |
| largest source of background radiation | radon |
| traditional units, also known as customary units what we use in the US, rest of the world uses SI system | Radiation units |
| measuring radiation in air only | Roentgen |
| radiation received by the patient | rad |
| occupational dose | rem |
| measure of radioactivity | curie |
| what is the purple of adding filtration | takes out the low energy photons that we don't want |
| primary cooling process of an X-ray tube | radiation |
| two types of X-ray production | characteristic and bremsstrahlung |
| bremsstrahlung X-rays are produced by | slowing electrons (the majority of the X-ray beam created at the target is Bremsstrahlung) |
| what direction do compton scatter rays go | any direction |
| X-rays interact with an atom without ionization during | Coherent Scattering |
| what is coherent scattering | EQUAL ENERGY being released; an X-ray that results with equal energy because no ionization took place, no energy was lost, the X-rays simply scattered into a different direction |
| scattered photons that retains up to 2/3 of the incident X-rays original energy happens during what interaction? | compton scattering |
| what is compton scattering | very little energy is necessary because it interacts with the outer shell electrons, they are very loosely bound |
| during this diagnostic energy range interaction (compton and photoelectric), the energy of the incident X-ray photon is completely absorbed | photoelectric effect |
| how does kVp effect photoelectric absorption? | if kvp increases, photoelectric absorption will decrease |
| two primary forms of interaction in diagnostic energy range are what | photoelectric and compton |
| what interaction involves an annihilation reaction | pair production, this will occur at 1.02 Mev and interact with the nuclear field |
| at energies above 10 mev, _____ interaction can take place | photodisintegration |
| what is photodisintegration | photon goes into the nucleus and nucleus has way too much energy and destroys itself |
| what role does mass density play | if the mass density of the tissue you are x-raying increases (number of atoms in tissue) differential absorption increases |
| What is the role of the atomic number? | If atomic number increases (# of protons), if you have more electrons for these radiation photons to interact w/ chances are ur probability is increased automatically that u're going to have more interactions of photoelectric absorption or compton scatter |
| What is contrast's role in imaging? | anytime we inject someone with contrast we are increasing the atomic number and the mass density of the tissues that the contrast is in |
| What affects transmitted X-rays? | what your kvp is, the higher the kvp the easier the X-rays can transmit through the patient. Atomic number and mass density will also play a role, if both go up we won't have as many transmitted xrays |
| What is the manifest image? | final (visible) image (during processing/developing) |
| What is the latent image? | What happens immediately after exposure (this is the unprocessed image, image on the film before it actually gets developed) (during exposure) |
| Histogram Type 1 | large spike toward the back (right side-blackness); direct exposure spike from anatomy that did not completely fill the IR |
| Histogram Type 2 | big hill; no spikes on either side since anatomy filled the IR |
| Histogram Type 3 | spike on front and back; spike on front is whiteness and back is blackness; contrast or prosthesis |
| What is the importance of histogram collimation? | computer cannot fix poor collimation, can fix 120% over exposure or 60% under exposure |
| CR Steps (1&2 of 5) | 1. Radiation strikes imaging plate 2. Electrons of phosphors raised and trapped in higher energy state |
| Cr Steps (3-5 of 5) | 3. imaging plate exposed to laser light to release electrons 4. photomultiplier tube detects light emission of electrons as they return to their stable state 5. imaging plate exposed to intense white light |
| the ability to absorb xrays | detector quantum efficiency |
| how easily does the image receptor give off light in comparison to the X-rays absorbed | conversion efficiency |
| want an IR that can absorb X-rays easily and readily | lower DQE and CE and have a lower patient dose |
| QC program includes | acceptance testing, routine performance monitoring and maintenance |
| focal spot size is measured with a ____ | pinhole camera |
| warped screens, warped cassettes, worn felt contacts, basically how well is our IR lining up with our film and our screen | wire mesh test |
| Changing your mA and your time station for the same mAs you should get the same density and mR output | reciprocity |
| keeping the exact same mAs and just simply making the same exposure over and over resulting in the same density | reproducibility |
| make an exposure at 5 mAs then 10 mAs then 20 mAs, each time that we double it we should be seeing double the amount of density | linearity |
| accuracy of the collimator | kVp - 10% |
| QA | people |
| QC | equipment |
| film should be stored at what humidity | 40-60% |
| dust/dirt, foreign objects, patient motion and fog are examples of what | exposure artifacts |
| pi lines, guide shoe marks, hesitation marks and fog are examples of what | processing artifacts |
| static, fog, kink, dust or dirt artifacts are from | storage and handling |
| checking how consistently our radiologists image interpretations match the ultimate patient diagnosis | outcome assessment |
| 120% over/60% under exposure can be tolerated in ____ ____; much wider exposure latitude | digital imaging |
Created by:
sarahdugan
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