Radiology Physics
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| State the maximum permissible tube leakage. | show 🗑
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| show | Reduces electric shock, electrical insulation and heat dissipation
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| show | When filament is heated enough, ion production begins the boiling off of electrons (the creation of ions through heat)
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| show | 2200 degrees C
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| show | 3410 degrees C
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| show | Thoriated tungsten (tungsten with thorium)
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| show | Nickel with rhenium
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| Compare the benefit of a smaller focal spot to the benefit of a larger focal spot | show 🗑
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| Compare the production of heat to the production of x-rays in the x-ray tube | show 🗑
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| show | Normal is 3400 rpm and high speed is 10,000 rpm
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| show | Induction motor
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| Explain what the stator is and where it is located | show 🗑
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| Explain what the rotor is and where it is located | show 🗑
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| Explain the line focus principle and how it is used in the design of an x-ray tube | show 🗑
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| show | area on the anode target that is exposed to electrons from the tube current
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| Effective focal spot size | show 🗑
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| show | AFS – area struck by electron beam. EFS – area from IR perspective by angling of the anode (AFS always larger than EFS)
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| Compare relationship between anode angle and effective focal spot size | show 🗑
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| show | As anode angle increases so does anode heat capacity
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| State what happens to field coverage as anode angle increases | show 🗑
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| State what happens to resolution as anode angle increases | show 🗑
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| Heel effect | show 🗑
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| show | Image quality improves with anode directed over smaller area cathode over thicker side FAT CAT
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| show | Spatial resolution greater on anode side with more focal spot blur (less resolution) on cathode side
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| show | As SID increases anode heel effect decreases (divergence of beam?)
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| State the effect field size has upon anode heel effect | show 🗑
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| State the effect anode angle has upon the anode heel effect | show 🗑
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| Explain what is meant by extra focal or off-focus radiation | show 🗑
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| show | Radiation, conduction and convection
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| Read a tube rating chart and determine whether an exposure is safe | show 🗑
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| Calculate heat units produced in a single phase x-ray machine when given a technique | show 🗑
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| Calculate the heat units produced in a three phase 12-pulse x-ray machine when given a technique | show 🗑
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| Read an anode cooling chart or housing cooling chart to determine the exposure capacity of an x-ray tube | show 🗑
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| State two types of interactions that produce diagnostic x-rays | show 🗑
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| State which of these two is an ionizing event | show 🗑
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| Explain how a characteristic interaction produces x-radiation | show 🗑
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| show | Result from interaction between a projectile electron and a target nucleus. The electron is slowed, its direction is changed and leaves with reduced kinetic energy. This loss of kinetic energy reappears as an x-ray. Can have energy up to 70 kVp
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| State the relationship between x-ray energy and wavelength | show 🗑
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| Explain how changes in mAs affect x-ray beam quantity and quality | show 🗑
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| show | Increasing kVp increases quantity and quality (and vice versa)
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| show | As filtration increases quantity decreases and quality increases
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| show | Target Z number increases beam quantity and quality increases
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| Explain how changes in generator power (voltage waveform/ripple) affect x-ray beam quantity and quality | show 🗑
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| show | Quantity, exposure and intensity
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| show | mR and Graya (milliroentgens or gray in air
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| show | X-ray quantity and radiographic density are directly proportional
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| show | X-ray quantity increases patient dose increases
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| List four major factors affecting x-ray quantity | show 🗑
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| show | Directly proportional (mA is a measure of tube current-what is traveling across the tube not x-rays)
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| show | Double the mAs double the x-ray intensity
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| State the relationship between kVp and x-ray intensity | show 🗑
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| show | The intensity of the radiation at a location is inversely proportional to the square of its distance from the source of radiation
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| show | I1÷I2 = (D2÷D1)2
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| show | Density maintenance law or Square law: compensate for a change in SID by changing mAs by the factor SID2 [mAs1÷ mAs2 = (SID1÷SID2)2]
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| Explain the relationship between filtration and patient dose | show 🗑
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| show | As energy increases penetrability increases
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| show | Quality is the penetrability of the beam. (increase quality = increased penetrability)
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| State how the quality of an x-ray beam is measured | show 🗑
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| Explain the relationship between HVL and beam penetrability | show 🗑
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| State the effect increasing SID will have upon beam quantity (intensity) | show 🗑
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| show | SID has no effect on beam quality
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| State what happens to the HVL of a beam as the energy of a beam increases | show 🗑
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| show | To decrease patient dose (skin dose)
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| Define a compensating filter | show 🗑
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| show | Energy of the beam, mass density, subject atomic number (Z number)
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| show | Photoelectric and Compton
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| show | Classical, Rayleigh, Thompson
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| Describe what happens during a coherent scattering event | show 🗑
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| show | Incident photon and scattered photon have same amount of energy. Direction of the scattered x-ray is different from that of the incident x-ray
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| show | The incident photon interacts with an outer-shell electron and ejects it from the atom, thereby ionizing the atom. The x-ray continues in a different direction with less energy
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| show | Photon has a change of direction and a loss of energy
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| show | Compton electron comes out of its shell and goes on its own way (usually somewhere in the body)
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| Explain what happens to the probability of a Compton interaction occurring as the energy of the incident photon increases | show 🗑
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| Explain what happens to the probability of a Compton interaction occurring as the atomic number of the subject atom increases | show 🗑
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| Explain what happens to the probability of a Compton interaction occurring as the mass density of subject atom increases | show 🗑
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| show | Radiographic contrast decreases as Compton scatter increases
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| State the effect Compton scatter has upon radiographic density | show 🗑
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| show | Ionizing interaction with inner-shell electrons. Incident x-ray is totally absorbed during ionization of an inner-shell electron. The incident photon disappears, and the K-shell electron (now a photoelectron) is ejected from the atom
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| Describe what happens to the incident photon | show 🗑
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| Compare photoelectric interaction with a characteristic interaction | show 🗑
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| show | As the energy of the incident photon increases less chance of a photoelectric interaction
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| show | As subject atomic number increases photoelectric interaction increases dramatically (X3)
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| Explain what happens to the probability of a photoelectric interaction occurring as the mass density of the subject atom increases | show 🗑
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| Explain what happens during a pair production event | show 🗑
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| State how much energy is required for a pair production event to occur | show 🗑
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| show | Photon absorbed directly by nucleus, nucleus is raised to an excited state and instantly emits a nucleon or other nuclear fragment
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| State how much energy is required for a photodisintegration event to occur | show 🗑
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| show | Substance that absorbs x-rays (appears white on an x-ray)
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| show | Substance that easily transmits x-rays (black/dark on an x-ray)
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| show | Both decrease as energy increases but a HUGE decrease in photoelectric (X3) compared to decrease in Compton
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| Compare changes in probability of a photoelectric interaction occurring to the probability of a Compton interaction occurring as subject matter atomic number increases | show 🗑
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| Compare changes in probability of a photoelectric interaction occurring to the probability of a Compton interaction occurring as subject mass density increases | show 🗑
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| show | Air (increases transmission of x-rays)
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| show | Compton & photoelectric
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| show | Compton
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| Give the interaction that contributes greatest to patient dose | show 🗑
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| State the interaction that is the major cause of film fog | show 🗑
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| show | Spatial – differentiate by sizeContrast – differentiate between tissue (shades)
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| show | Result of random nature of interaction with IR – not enough signal – photon starved
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| show | Increase number of x-rays High mAs, low kVp and slower image receptors will reduce quantum mottle (decrease in mA increases quantum mottle)
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| Distinguish between a densitometer and a sensitometer | show 🗑
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| show | Optical density will increase by 0.3 (LOG of 2 = 0.3)
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| show | Optical density is proportional to how much energy reaches the film (mAs=mAs)
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| Define radiographic contrast | show 🗑
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| Compare terms: High contrast & Low contrast | show 🗑
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| Compare terms:Long scale & Short scale | show 🗑
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| Compare terms:High kVp & Low kVp | show 🗑
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| show | More vertical – more contrast, more speed – closest to y-axis, less latitudeMore horizontal – less contrast, less speed – farther from y-axis, more latitude
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| show | New IR speed ÷ old IR speed = old mAs ÷ new mAs (inversely proportional)
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| Define radiographic latitude | show 🗑
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| State the effect developer time has on contrast, speed and fog | show 🗑
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| State the effect developer temperature has on contrast, speed and fog | show 🗑
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| List the three geometric factors of radiographic quality | show 🗑
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| show | Object size = image size (SOD ÷ SID) or image size ÷ object size = SID ÷ SOD
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| Explain how to minimize magnification | show 🗑
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| Give the situation which will cause elongation | show 🗑
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| Give the situation which will cause foreshortening | show 🗑
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| show | Softening of the edges of structure on an image caused by the size of the focal spot (blurred region of radiograph)
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| Calculate focal spot blur when given focal spot size, SID and OID | show 🗑
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| show | Focal spot size has no effect on magnification
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| show | Large focal will have less softening (focal spot blur)
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| show | Kilovoltage increases contrast decreases and latitude increases (wide) and vice versa
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| show | Good patient instruction
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| show | Short exposure time
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| State the relationship between image receptor speed and patient dose | show 🗑
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| show | Kilovoltage increases contrast decreases and latitude increases (wide) and vice versa
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| show | Good patient instruction
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| show | Short exposure time
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| show | As image receptor speed increases patient dose decreases
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