X-Ray Physics Lecture 1
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JosephM515 on April 30, 2012
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Terms | Definitions |
|---|---|
 the propagation of energy from point to point | radiation |
| 3 types of radiation | PARTICULATE MECHANICAL ELECTROMAGNETIC (EM) |
| in particulate radiation, ___-containing particles are propelled at high speeds determined by the ___ of each particle and the ___ of the explosive event (particle ___, ___ or ___) producing ___ rays, ___ particles, ___ particles, ___ beams, ___ beams, ___ rays... | mass; mass; energy; collision; fission; fusion; cathode; alpha; beta; neutron; proton; cosmic |
| mechanical radiation requires an ___ medium (matter) to propagate ___ from one place to another | elastic; energy |
| in EM, the transmission of energy is in the form of a ___/___ having both and electric and a magnetic component. a wave with just ___ of these components cannot exist. EM radiation is produced by ___ electrical currents and ___ currents. possesses both ___-like (freq. & wavelength) and ___-like energy (energy & momentum [___]) properties | wave/disturbance; one accelerated; oscillating wave; particle; photon |
| EM radiation composed of an electric field and a magnetic field in planes ___ to each other | perpendicular |
| EM radiation is characterized by its ___, ___, and ___. when EM waves are ordered in accordance with their freq. or wavelength, this ordered array is called the ___ ___. | frequency, wavelength, energy; ELECTROMAGNETIC SPECTRUM |
| XRs contain no ___ | mass |
| XRs are electrically ___ | neutral |
| XRs are ___ | invisible |
| XRs travel at what speed? | light speed |
| XRs can/cannot be focused by a lens? | cannot |
| XRs are highly ___ | penetrating |
| XRs travel in ___ lines in a ___ beam. | straight; divergent |
| XRs produce ___ and ___ radiation. | secondary; scatter |
| XRs cause certain substances to ___. | fluoresce |
| XRs can expose ___ ___ | photographic film |
| XRs have a medically useful range of energies from about ___ keV/___ E to about ___ keV/___ E | 15; low; 150; high |
| keV=? | thousand electron volts |
| XRs can convert themselves to ___ when passing through matter | heat |
| XRs can ___ matter | ionize e.g., ionization, ionizing radiation |
| to eject orbital electrons from atoms | ionize |
| XRs can produce ___ changes by means of induced molecular ___. | biological; alterations |
| what type of wavelength, freq., and energy level do soft XRs have? | long (SOFT); low; low (LOW PENETRATION) |
| what type of wavelength, freq., and energy level do hard XRs have? | short (HARD); high; high (HIGH PENETRATION) |
| low energy (soft) XRs have poor ___, most are ___. ___ absorbs >6 times more of these soft XRs than ___ tissues. to get an image, it is necessary to ___ the region with a ___ number of XRs. ___ is not penetrated well; maybe not at all if the energy is ___ enough. if an enormous number of XRs are used, eventually the soft tissues become ___, then ___ (overexposed), but bone cannot be penetrated and remains ___. THIS IS TERMED ___ ___. SINCE IT TOOK A TREMENDOUS NUMBER OF XRs TO GET THIS HIGH CONTRAST IMAGE, THE DOSE OF RADIATION WAS THEREFORE ___. | penetration; absorbed bone; soft flood; huge bone; low grey; black; white HIGH CONTRAST HIGH |
| HIGH ENERGY (HARD) XRs: ___ matter easily, few are absorbed. bone absorbs only ___-___ times more of these hard XRs than soft tissues (bone & soft tissue look nearly the same). since hard XRs are very penetrating, only a ___ number of XRs are necessary to get thorough ___. if a large number of hard XRs are used, the whole image (bone & soft tissue) becomes ___, then ___ (overexposed), therefore, only a ___ number of hard XRs can be used. bone and soft tissue are nearly ___ penetrated. therefore, bone and soft tissue are similar in ___. THIS IS TERMED ___ ___. SINCE IT TOOK A LOW NUMBER OF XRs TO GET THIS LOW CONTRAST IMAGE, THE DOSE OF RADIATION WAS THEREFORE ___. | penetrate 1.2-1.5 small; penetration grey; black; small equally appearance LOW CONTRAST LOW |
| A HIGH CONTRAST IMAGE requires a relatively ___ dose of ___ energy XRs. | HIGH; LOW |
| A LOW CONTRAST IMAGE requires a relatively ___ dose of ___ energy XRs. | LOW; HIGH |
| intensity varies throughout beam; sharpness & resolution (focal spot varies throughout beam)...what do these properties describe? | heel effect |
| 3 components of early XR tubes | source of electrons means to accelerate these electrons high Z target to be bombarded by the electrons |
| Roentgen made his discovery with a ___ TUBE (not designed/optimized for XR production) | CROOKES |
| re: EARLY GAS TUBES, the source of electrons was the ___ ___ gas inside; it was difficult to get ___ XR production (mA was hard to control) | partial pressure; consistent |
| COOLIDGE TUBE (1st tube with a heated ___, termed hot ___ tube); the source of electrons was the ___ (tube evacuated to a near ___); consistent ___ resulted in consistent XR production. | filament; cathode; filament; mA |
| 4 components of basic XR tube design | 1. CATHODE ASSEMBLY (-) CHARGE 2. ANODE ASSEMBLY (STATIONARY/ROTATING) (+) CHARGE 3. LOW VOLTAGE (FILAMENT/ELECTRON-RELEASING) CIRCUIT (mA) 4. HIGH VOLTAGE (ELECTRON ACCELERATING) CIRCUIT (kVp) |
| CATHODE ASSEMBLY (-) CHARGE: filament (___ emission/___ Effect) each filament sits in its own ___ focusing cup | thermionic; Edison nickel |
| SMALL FILAMENT produces the SMALL ___ ___ (___) ___ or ___ mm rated focal spots better ___ (sharper image, less focal spot ___) can only be used with lower ___ settings therefore produces ___ XRs, ___ XR output | FOCAL AREA (SPOT) 0.6; 1.0 definition; blur mA fewer; lower |
| LARGE FILAMENT produces the LARGE ___ ___ (___) ___ or ___ mm rated focal spots poorer ___ (___ image, more focal spot ___) supports higher ___ settings produces the ___ XR output for that tube | FOCAL AREA (SPOT) 1.2; 2.0 definition; blurrier; blur mA maximum |
| ANODE ASSEMBLY can be either ___ or ___ and has a ___ charge | stationary; rotating; + |
| ANODE ASSEMBLY has a ___ ___ target | high Z (W) |
| stationary anode design: (stationary ___); ___ block (target) bonded to a bulky copper assembly (___ sink) | target; tungsten; heat |
| rotating anode design: rotating target ___ on a ___ disk the target area now becomes a ___ target track with 100+ times (___ focal spot) and 200+ times (___ focal spot) the target area of a stationary anode design tube -- ___ hundreds of times the heat allowing hundreds of times the XR production before anode ___ occurs. | track; tungsten circular; large; small; dissipates; damage |
| higher ___ capacity allows the higher tube ___ (mA) which allows increased XR output allowing for ___ focal spots and/or ___ exposure times | heat; currents; smaller; shorter |
| the larger the ___ & ___ of the anode disk, the ___ the XR output, and also the more ___ the tube 125,000 HU tube costs about $4500 (standard equipment) 400,000 HU tube costs about $8500 (extra ___ capacity/___) | diameter; mass; higher; expensive; heat; power |
| LOW VOLTAGE (___/electron-___) CIRCUIT (mA): source of ___ | filament; releasing electrons |
| HIGH VOLTAGE (electron ___) CIRCUIT (kVp): means to ___ the electrons | accelerating accelerate |
| gamma rays come from the ___; x-rays come from ___; however, the 2 end products are identical if their ___ are the same | nucleus; electrons; frequencies |
| a ___ is an imaginary particle that travels at the speed of light | photon |
| which descriptive system is used to categorize EM radiation? | ENERGY (keV) |
| dislodging an electron from an atom is termed ___ | IONIZATION |
| which is not a type of EM radiation? | ALPHA PARTICLES |
| increasing the frequency of EM also increases ___ | ENERGY |
| a hard XR beam consists primarily of XRs that are primarily ___ wavelength, ___ freq., and ___ energy | short; high; high |
| to LOWER the X-radiation dose to a patient, ___ the XR energy, then ___ the quantity | increase; lower |
| in XR tube, which particle is accelerated to produce XRs? | electron |
| how many filaments are present in a general purpose XR tube? | 2 |
| advantage of a rotating anode XR tube is? | better heat distribution; more XRs |
| be able to identify and know the significance of the components on the diagram that follows. |  |
| What is the following diagram an example of? |  EM Radiation |
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