S2: Applications Practice Questions
X-ray Tubes: How many rotations would a high speed 8600rpm anode make in an exposure of 0.7sec?
100 8600/60 = 143.3 x 0.7 = 100
X-ray Tubes: If a material is absorbing radiation exponentially at 10% per unit thickness, the radiation intensity would decrease in the sequence....
100%, 90%, 81%, 73%, 65%
Collimators How many lead panels open/close in a three layer, multi leaf collimator
12
X-ray Generator, etc Explain High tension transformers
Converts low voltage into the kilovolts required for the production of x-rays
X-ray Tubes: Increasing the mAs, the MRT is
Creating more radiation
Fuses and Circuit Breakers What does a High Rupture Device look like
Cylinder tube with wires coming out either end
Fibre Optics TRUE or FALSE In a single strand fibre optics, the diameter of the core is larger than the thickness of the cladding
False
Filtration TRUE or FALSE Increase mA also increases shortest wavelength x-rays
False
Filtration TRUE or FALSE Using a filter cuts out the short wavelength x-rays completely
False
Filtration TRUE or FALSE Using filter reduces number of longer wavelengths in x-ray beam
False
X-ray Tubes: Direct Current (DC) produces the rotating magnetic field that causes the anode to rotate TRUE or FALSE
False Need AC Current
Image Intensifiers In II, the spatial warping caused by the interference of external magnetic fields is called...
S distortion
Flat Panel Detectors What are the steps involved in digitising an analogue image and can the original image be recovered
Scanning Sampling Quantisation Irreversible
X-ray Generator, etc Which form of rectification is now obsolete
Self rectification
Fuses and Circuit Breakers If you check the glass cartridge type fuse and you see that it is black in the middle with broken wire, what has happened?
Short circuit
Filtration With age, inherent filtration tends to increase. Why?
Tungsten vaporises and is deposited inside the glass insert
X-ray Tubes: On a graph showing an increase of the bremsstrahlung line on the X axis, what has been adjusted
kVp
X-ray Generator, etc A step down transformer has ___ turns on the secondary side than the primary
less
Autotimers Name 5 factors that influence the time taken for the required exposure to trigger the AEC to terminate the exposure
mA Grid used Density of reference level step selected Z of structures within pt part examined SID Filter used Thickness of pt being examined
X-ray Tubes: On a graph showing an increase of the bremsstrahlung line on the Y axis, what has been adjusted
mAs
Filtration What is inherent filtration
the filtration of useful beam that takes place due to the permanent components of the x-ray tube
X-ray Generator, etc The num of turns on primary and secondary sides need to be the ____ in isolating transformers
the same
Autotimers A photodiode is capable of
Converting x-ray radiation into an electrical signal
Camera Describe the term ADC
Converts analogue electrical signal values into a digital signal
Filtration What is the benefit to the pt of 'hardening the beam'
Lowers the patient dose
Autotimers If you were performing Chest xray, what AEC chamber would you choose for PA
Right and Left
X-ray Tubes: Two disadvantages of rotating anodes
- Cost - Issues with the bearings - they wear out
Collimators What are the purposes/functions of a collimator
- Define the size/shape of x-ray beam - Reduce effect of off-focus radiation - Improve image resolution by reducing production of scatter radiation
Autotimers What is purpose of ABC or AERC during fluroroscopy
- ABC/AERC measures x-ray intensity and will send a message to the generator to increase/decrease x-ray exposure rate - it attempts to keep SNR constant regardless of thickness of pt - also increases exposure rate when magnifictaion mode is used, compensating for enlarged pt
Autotimers AEC was developed for the purpose of
- Achieving consistent exposures - Reducing repeats - Ensuring diagnostic quality images
X-ray Tubes: Earlier we said that 97-99% of the energy used in the production of x-rays is converted into heat. What are the ways that heat is dissipated
- Conduction - Convection - Radiation
X-ray Tubes: What are the advantages of a rotating anode
- Higher mA values possible (rotating anode = doesn't get as hot = can use higher mA) - Higher kVp values possible - Longer exposure time possible
X-ray Tubes: Two advantages of rotating anodes
- Higher mA/kVp - Distributed evenly - High repetition rate (able to repeat images when needed)
X-ray Tubes: In order for an x-ray tube to produce x-rays there are three essential things that MUST happen
- There must be a potential difference between cathode and anode - The anode must be positive in respect to the cathode - The cathode must be emitting electrons
Autotimers List reasons why detector cells may not be covered by the area of interest resulting in an underexposed image
- anatomy part too small - not centred correctly
Autotimers Reasons why an AEC will underexpose an image
- if the pt is too large the back up timer shorts out before sufficient exposure is given - collimation isn't tight resulting in extra scatter - anatomy size too small - density control selected below what actually required for pt - incorrect detector cell configuration, under tissue less dense or thinner than the tissues of interest - detector cells not fully covered by tissue of interest
Image Intensifiers Advantages of II over fluoroscope
- much lower dose used than conventional x-ray - Improved image visibility, did not require time for eyes to adjust
Autotimers What are two of the AEC limitations
- need accurate collimation (too large field = excessive amounts scatter and may cause AEC to shut off too soon) - can't use/modify exposure setting with prosthesis
Image Intensifiers Disadvantages of original fluoroscope that was designed by Thomas Edison
- poor picture, needed dim light - high dose to pt and radiologist
X-ray Generator, etc What are purposes of transformer in an x-ray cirucit
- step down the voltage - step down the current - isolate a circuit
Fuses and Circuit Breakers What is classified as being part of a fuse construction
- the holder or carrier - the base into which the holder/carrier fits - the element (eg wire that melts)
X-ray Generator, etc What are the ways to reduce copper losses
- use purest material for the windings - keep the windings as short as possible - keep the cross sectional diameter as large as possible
Autotimers Advantages of using solid state autotimers
- very small size - almost 0 attenuation of x-ray beam - consistency - faster response time
Television and Displays In a broadcasted analogue television signal, what were the three components of a TV channel signal
- video - synch pulse - audio
Autotimers Reasons for AEC to overexpose
- wrong bucky - incorrect density step selection malfunction of AEC - incorrect detector cell selected - radiopaque artefacts within pt or outside (sandbags,etc)
Filtration Name 4 material that compensatory filters may be composed from
1. Aluminium 2. Copper 3. Tin 4. Acrylics
X-ray Tubes: Complete: Anodes made from __1___, __2__ are prone to __3__ and __4__ due to the continual __5__ and __6__, and the mechanical __7__ due to rotation. ____8____ materials are structurally ___9___. Anodes are normally made from an alloy which is a ___10__ of tungsten and ___11___ which is more __12__ to cracking and pitting.
1. Pure 2. Tungsten 3. Pitting 4. Cracking 5. Heating 6. Cooling 7. Stresses 8. Alloy 9. Stronger 10. Blend 11. Rhenium 12. Resistant
Tube Ratings: Why is an exposure of 80kVp, 400mA for 0.1sec (1)unsafe exposure, yet the same amount of x-rays produced using 80kVp and 200mA (2)would be safe?
1. lands to the right of the line (following along 80kVp until 0.1sec, see if above or below 400mA line) 2. follow along until 0.2 sec (b/c want same exposure so 200 x 0.2sec) and see it is under the line
Autotimers What are two reasons for back up timer on AEC
1. prevent excessive heat overload on the tube 2. unnecessary radiation to the patient
Collimators A single leaf collimator has a ___1__ set of __2__ leaves that work together as __3__/__4__
1. single 2. four 3. opposed 4. pairs
Autotimers CSP 5. 5.28 the minimum response time of the AEC device with the appropriate chamber selected for the x-ray projection shall be less than __________ for a HF x-ray machine?
10 milliseconds
Tube Ratings: If the first exposure of the day was to heat the anode to 350,000 HU, how long would it take for it to cool down completely
14min
Camera If a modern CMOS camera sensor has 5,100 pixels by 3,500 pixels, what is the total number of pixel on the sensor
17,850,000
X-ray Tubes: The ideal anode angle for a rotating anode from vertical is
17-20 degrees
X-ray Tubes: Using an ionisation chamber to measure the amount of radiation, an exposure at 100cm produces a reading of 76mGy. What reading would you expect if you increased the distance to 200cm?
19 New exposure/old exposure = new dis(2)/old dis(2) x/76 = 200(2)/100(2) x/76 = 40000/10000 x/76 = 4 x = 76/4
X-ray Tubes: How many rotations would a standard 3000rpm anode made in an exposure of 0.04secs?
2 3000/60 = 50 x 0.04 = 2 50 ties in with frequency
X-ray Generator, etc A transformer has 40 turns on the primary windings and 400 turns on the secondary windings. If the primary current is 20 amps, what would the output current be on the secondary windings?
2 amps
Television and Displays If a plasma screen is said to be Full HD (1920 x 1080), the total number of pixels on the screen would be
2,073,600
Fibre Optics Speed is another advantage for the use of fibre optics. AT approx what speed does signal travel inside a fibre optic
200,000 kilometres per second
X-ray Tubes: Generally what is the upper limit of mA for a fine focus exposure
200mA
X-ray Tubes: If the recommended manual mAs exposure for a chest radiograph on a 5yr old child in 3.2mAs, then this can be achieved by using what?
200mA, 0.016seconds
X-ray Generator, etc A transformer has 40 turns on the primary windings and 400 turns on the secondary windings. If the primary voltage is 20 volts, what would the output voltage be on the secondary windings?
200volts
Image Intensifiers The diameter size of the output phosphor region in an II is
25mm
Television and Displays In a colour CRT television, how many electron guns were there
3
Tube Ratings: If the first exposure of the day was to heat the anode to 250,000 HU, what is the minimum time period that it will need to cool for, before you can make a second exposure of 250,000 HU?
3mins
Collimators The number of lead panels that open/close in a single leaf collimator
4
X-ray Generator, etc A full wave rectification has ____ rectifiers between the secondary side of HT transformer and the tube
4
Fibre Optic The Southern Cross network is a 28,900 submarine cable that connects, Australia, NZ, Fiji, Hawaii and the West Coast of the USA. It incorporates repeaters, to boost the signal, every _______________.
40-70 kilometres
X-ray Tubes: An exposure of 80mAs, @70kVp is the same in effect as....
400mA, 0.2sec, @70kVp
Collimators If you increased collimated field from 20x20 to 25x25cms. what is the % increase between collimated area 1 and collimated area 2
56%
Tube Ratings: You perform two x-rays, one directly after the other. The first exposure is 150,000 HU and the second is 100,000 HU. How many minutes will it take for the anode to cool to only 50,000HU
5mins for anode to cool 6min to cool to 50,000 - 1 (b/c 1min between 150,000 and 100,000)
Autotimers CSP 5 5.29 A devise shall be installed which can be set to terminate the exposure after a time no greater than _____ seconds or a maximum of _____mAs, which ever is the lesser.
6 600
Flat Panel Detectors If a 430mm x 350mm detector has 2,867 by 2,335 microscopic detector elements, what is the total number on the entire detector
6,694,445
Television and Displays If a 14 inch CRT television had 625 raster lines, how many raster lines would there be in a 29 inch television
625
Grids and Bucky's You are about to go to the ward to x-ray a patient's chest. Their previous image was taken at 85 kVp, 6 mAs, 180cm with no grid. It looks to have a lot of scatter on it and the MRT informs you that the patient is in fact quiet large. Using this information, you decide to use a grid for your x-ray. The grid you choose has a grid ratio of 8:1, a grid frequency of 50 lines per cm and a grid factor of 4. Calculate the new exposure
85kVp/24mAs/180cm (6mAs x grid factor 4 = 24)
Tube Ratings: Your first exposure generates 250,000 HU. 3 minutes later you make a second exposure of 250,000 HU. What will the heat units have dropped to after a four minute wait from the time of the second exposure?
90,000HU
X-ray Tubes: The percentage of energy that is converted into heat when the freed cathode electrons interact at the anode is approximately
97%
Filtration What is a compensatory filter
A filter applied by MRT to even out difference thickness of body issue
Grids and Bucky's Larger body parts create more interactions between x-rays and tissue, so more secondary radiation is created. What piece of equipment do MRTs use to reduce this reaching the IR?
A grid
Television and Displays The scan pattern of electron beam found in cathode ray TV tubes and vidicon cameras to produce an image was called....
A raster
Autotimers Quantum mottle is related to
A shortage of x-ray photons in the beam
Television and Displays Label parts of television TFT pixel
A. storage B. pixel electrode C. TFT - thin film transistor
Autotimers What is the name or abbreviation of the automatic control when using modern fluroscopy
AERC Automatic Exposure Rate Control
Camera Describe the term Target Assembly
Acts as an anode
Image Intensifiers Magnification using an electrostatic II, is controlled by....
Adjusting the focal point of the electron beam
Flat Panel Detectors Disadvantage when using direct flat panel detectors is...
Affected by humidity and temp
X-ray Tubes: The main reason that the anode is made from a tungsten alloy rather than pure tungsten is?
Alloyed tungsten has less chance of cracking when repetitively heated and cooled
Filtration the effectiveness of a filter is related to its
Aluminium equivalence
Fuses and Circuit Breakers A fuse is rated in
Amperage
Grids and Bucky's Explain why the grid factor increases as the grid ratio does
As the ratio increases, the height of the radiopaque material increases. This decreases the amount of radiation reaching the IR
Image Intensifiers In II, the process where the electronic signal is increased or decreased to improve the image quality, rather than changing exposure is called...
Automatic gain control
X-ray Generator, etc Which type of transformer is unsuitable to high voltage
Autotransformer
X-ray Tubes: Compton scatter with a scattering angle of 180 degrees is called
Back scatter
Television and Displays If a vertical polarising filter and a horizontal polarising filter used in LCD televisions were to be placed on top of one another and a while light source was shone from behind the filters, what would you see?
Blackness
Camera If the read out process for a camera was written as: 'the electrical charges of the first row of pixels are transferred to the read out register. Once the first row has been read, the second row drops down to the first row, the third row drops into the second row, the fourth row, drops into the third row...' What type of camera sensor chip is being described?
CCD
Camera What type of camera sensor chip has a fill factor of 100%
CCD
Camera Describe the term Signal Plate
Can be found at transparent input end
Timers Which component begins to charge after the exposure button has been pressed
Capacitor
Flat Panel Detectors The material used as the scintillation layer in the construction of an indirect conversion FPDs is
Cesium Iodide
Image Intensifiers The input phosphor used i an II uses
Cesium iodide
Camera In digital camera, if the signal output from imaging chip has to be fed into an amplifier and then on to the ADC within the camera what sort of camera imaging chip is it
Charge Coupled Device
Fuses and Circuit Breakers What does a cartridge fuse look like
Clear cylinder tube with metal either end
Camera In digital camera, if the signal output from the imaging chip has already been amplified and digitised, what sort of camera imaging chip is it?
Complementary metal oxide semiconductor
Flat Panel Detectors When explaining an analogue radiograph you could describe it using what terms
Continuous in space and continuous in value
X-ray Tubes: The mA is....
Controlled by the temperature of the filament
Timers Which of the following isn't a type of timer used to terminate an exposure a. additional timer b. dead mans switch c. An interlock d. guard timer
Dead Mans Switch
Image Intensifiers When magnification of an II image is performed, the minification gains....
Decrease
X-ray Tubes: Raising the kVp.....
Decreases the wavelengths in the beam
Flat Panel Detectors The 'smallest detector element that an x-ray can be captured in' is the description of what term
Del
Television and Displays What does the acronym DICOM stand for
Digital Imaging and Communication in Medicine
Flat Panel Detectors At the end of the scanning stage of digitising an analogue image into a digital image, the image is.....
Discrete in space and continuous in value
Flat Panel Detectors At the end of quantisation stage of digitising an analogue image into a digital image, the image is.....
Discrete in space and discrete in value
X-ray Tubes: The inverse square law is a result of what?
Divergence
Image Intensifiers Correct full name for the II is a
Electrostatic Image Intesifier
Collimators TRUE or FALSE Off - focus radiation is classified as scatter radiation
FALSE
Image Intensifiers TRUE or FALSE The electrostatic lenses used in II to narrow and focus the beam of electrons, are positively charged
FALSE
Autotimers TRUE or FALSE The AEC is capable of altering the mA during the exposure
FALSE AEC only controls the length of the exposure and therefore conseqently the total mAs. BUT optimum kVp and mA must still be selected and set by the MRT
Fuses and Circuit Breakers TRUE or FALSE The purpose of a residual current device is to protect the equipment from electrical damage
FALSE Unlike fuses and other circuit breakers, an RCD is designed to protect users from electrocution or burns from electrical fires.
Fuses and Circuit Breakers TRUE or FALSE A fuse is a resettable device
FALSE a circuit breaker is resettable
Fibre Optics A major advantage for the use of fibre optics over copper cables, is.....
Fibre optics have a higher capacity or bandwidth for information
Television and Displays The components of a cathode x-ray tube, in order as they appear from cathode to the screen, are...
Filament, modulator, accelerator, deflector cells
Flat Panel Detectors With FPD calculation: Detector surface of detector element/area of each individual detector element x 100/1 Is used to work out the:
Fill Factor
Filtration What piece of equipment may an MRT choose to use to even out the differences in thickness of the foot when performing a radiographic exam. AND What type of filtration will this be
Filter Compensatory
Flat Panel Detectors When being used to describe a digital detector, what would the initials FPD stand for
Flat panel detector
Collimators Where would you NOT find a fixed shape or diaphragm collimator? a. Dental Unit b. Cranial Unit c. Fluoroscopy Unit d. OPG
Fluoroscopy
Image Intensifiers The ratio of number of light photons created at the output phosphor to the number of x-rays at the input phosphor is the definition of what (num output light photons/num input light photons)
Flux Gain
Grids and Bucky's Which of the following exposure factor manipulations DO NOT need to be considered when changing from a non-grid to a focus grid exposure? a. SID b. mAs c. Focal spot size d. kVp
Focal spot size
Grids and Bucky's Lucy has taken an x-ray on a paediatric patient is the emergency department for a possible SUFE. While her exposure factors were correct, her image needed repeating due to an error with the grid (white top and bottom, darker in middle) What type of grid has been used?
Focused Grid
X-ray Tubes: Explain the inverse square law
For every metre, the exposure becomes squared. Therefore the dose is reduced. eg. 2m = quarter the dose
Image Intensifiers In relation to II, the difference between the intensity of light at the input screen and the intensity of light a the output screen is called the...
Gain
X-ray Generator, etc What are examples of conductors
Glass Conductors = copper, silver, aluminium, brass, water Insulator = rubber, glass, plastics, dry wood and oil
Television and Displays What are 4 main components of an LCD television
Light source Polarising filters Twisted nematic LCD Colour screen
Fibre Optics Advantage = speed at which signal travels inside fibre. How is signal sent down the fibre optic
Light waves (other examples =laser and LED)
Flat Panel Detectors Spatial resolution of FPD is measured in...
Line pairs
X-ray Tubes: The anode heel effect is
Loss of intensity on the anode side of the x-ray caused by attenuation
Grids and Bucky's Complete the following: Grid _______ is the number of grid ______ per ________. High _______ of grid lines will show ________ distinct grid _______ on the image. The grid is said to be a ______ frequency grid. Low number of grid lines made by ________widths of _______ strips is more likely to cause ______ grid artefact on the image. This type of grid is said to be a ______ frequency grid. Low frequency grids will require less _____ as there are less grid strips to _____ the x-rays. Therefore using less _______ _____ than a high frequency grid.
Grid FREQUENCY is the number of grid STRIPS per CENTIMETRE. High NUMBER of grid lines will show LESS distinct grid ARTEFACT on the image. The grid is said to be a HIGH frequency grid. Low number of grid lines made by THICKER widths of RADIOPAQUE strips is more likely to cause DISTINCT grid artefact on the image. This type of grid is said to be a LOW frequency grid. Low frequency grids will require less mAs as there are less grid strips to ABSORB the x-rays. Therefore using less PATIENT DOSE than a high frequency grid.
Grids and Bucky's What could still occur when correctly using a parallel grid
Grid cut off may occur at the very edges of the image
Grids and Bucky's What's the equation to work out the grid ratio
Grid ratio = H/D (Height of radiopaque material/width of radiolucent interspace)
X-ray Tubes: Half Valve Layer (HVL) is defined as a thickness of attenuator that will
Half x-ray quantity
Fibre Optics Fibre optics have a core surrounded by an optical glass cladding. The core has what refractive index in relation to the cladding
Higher
X-ray Generator, etc Out of the 4 causes of transformer loss is best described as: "Lag in time where there is some residual magnetism which has to be cancelled after each change of polarity"
Hysteresis loss
Filtration Increasing filtration DECREASES/INCREASES the QUALITY/QUANTITY of the x-ray beam
INCREASES QUALITY
X-ray Tubes: How does a broad focal spot increase geometric unsharpness on a radiographic image
Increase penumbra
Grids and Bucky's What can you do to the SID/SOD/OID to help reduce secondary radiation reaching the IR
Increasing OID
X-ray Generator, etc Electromagnetic induction means that a current only flows when the magnetic field is....
Increasing an decreasing in strength
Flat Panel Detectors The FPD method which required a layer to convert x-ray photons into visible light photons and then the layer to convert the visible light photons in to an electrical signal is called....
Indirect Conversion
Image Intensifiers What part of the image intensifier converts the incident x-ray beam into visible light
Input Phosphor
Autotimers In autotimers the radiation is detected by the use of
Ion Chambers Solid State Devices
Camera Advantage of CCD camera is that it...
Is capable of capturing light from the infrared spectrum
X-ray Generator, etc Which statement best applies to the electrical term 'watt'
Is the rate at which electricity can do its work or the rate at which electricty is spent
Flat Panel Detectors What is the benefit of using cesium iodide in II and FPDs
It's needle like structures Benefit is that the long crystal format controls light dispersion. This controls the blurring and improves spatial resolution
X-ray Tubes: A pts initial chest x-ray was taken at 100cm. The next day you are required to perform a follow up chest x-ray at 180cm. What would be the required change to mAs needed to produce an image with similar density or brightness of the first radiograph
Just over three fold
Grids and Bucky's A secondary radiation grid is made up of hundreds of strips of ____ layered together with hundreds of strips of a radiolucent interspace material
Lead
Grids and Bucky's The main material used to construct the interspaces in a grid would be too hard to manufacture, so the next best suitable substitute to construct interspaces in DR grids is...
Main material = Air Next best thing = carbon fiber
Flat Panel Detectors The microscopic individual detector elements that make up the entire detector are expressed in specific measurements are called____
Microns
Fibre Optics Process used with fibre optics to maximise the bandwidth by using non-overlapping frequencies is called
Multiplexing
X-ray Tubes: Compton scatter is a source of....
Occupational exposure
X-ray Tubes: Biangular anodes work with two separate filaments which are....
One above the other
X-ray Tubes: Why does Classical/Coherent scattering have very little effect on x-ray images
Only very low energy photons are affected
X-ray Tubes: Rotating anode discs are often laminated using graphite, tungsten and molybdenum. What is the outer layer, inner layer, and bottom layer made out of
Outer = Tungsten Inner = Molybdenum Bottom = Graphite
X-ray Tubes: Characteristic radiation is produced by the
Outer shell electron moving inwards
X-ray Tubes: At 80kVp, Bremsstrahlung x-rays produced in a tungsten targeted x-ray tube....
Outnumber Characteristic c-rays
Image Intensifiers In order to produce an image with sufficient spatial resolution, which part of the II must have the smallest, very fine, crystal size
Output phosphor
Image Intensifiers What part of the II converts electrons into visible green light
Output phosphor
Flat Panel Detectors What would be the correct term used to classify CR Computed Radiography
Passive Detection
Image Intensifiers What part of the II converts light into electrons
Phorocathode
Flat Panel Detectors With direct conversion detectors, the amorphous selenium semi conductive materiail has what type of properties
Photo-conduction
Camera CCD and CMOS cameras are solid state devices that convert photons into electrons by a process called...
Photoelectric effect
X-ray Tubes: Which of the following interactions results in the total disappearance of the incident photon
Photoelectric effect
Television and Displays When we see a PA hand radiograph on an LDC display screen is actually a series of black and white.....
Picture elements (pixels)
Television and Displays Generally when discussing resolution of a television or display screen, the primary factor is
Pixel size
X-ray Generator, etc Which of the following statements is not true about HT transformers a. Primary windings are thick copper wires b. Secondary windings are thin copper c. Secondary windings are earthed d. Primary windings are earthed
Primary windings are earthed
Grids and Bucky's The type of grid that has tapered edges to lessen the impact of grid cut off is a...
Prismatic grid
Grids and Bucky's What was the most successful type of movement used in bucky mechanisms in older x-ray machines to remove the appearance of grid lines from the radiograph
Reciprocating
Television and Displays The colours of sub pixel filters on a colour LCD televisions are
Red, blue, green
Image Intensifiers Short definition of Photoemission
Release of electrons when stimulated by light
X-ray Tubes: Ionisation is the
Removal of an orbital electron from an atom
X-ray Tubes: In terms of radiation production, the term binding energy is defined as the energy required to
Remove an electron from a particular valence band or orbit
Timers The rate of change is determined by the ___ in electronic capacitance resistance
Resistor
Fuses and Circuit Breakers If you check the glass tube cartridge type fuse, and you can see the middle wire is broken and balled either end of the broken wire, what has happened?
Slow overload
X-ray Tubes: The greater the potential difference across the cathode and anode, the....
Smaller the wavelength of the x-rays in the beam
Fibre Optics Main disadvantage for the use of fibre optics over copper cables is...
Splicing and joining requires special tools and skills
X-ray Tubes: A rotating anode is turned by _____ coils which is induce a field into the ___ within the insert
Stator, Rotor
X-ray Generator, etc A filament heating isolation transformer is a type of
Step down transformer
X-ray Generator, etc If a transformer has 40 turns on the primary windings and 400 turns on the secondary windings it would be a....
Step up transformer
X-ray Generator, etc The electrons in an insulator are _______ ______ and the atoms are not free to move. An example of an insulator would be ________ a. Strongly bound, oil b. Loosely bound, plastic c. Strongly bound, silver d. Loosely bound, brass
Strongly bound Oil
Fuses and Circuit Breakers TRUE or FALSE A circuit breaker is a resettable device
TRUE
Grids and Bucky's The term grid factor indicates....
The amount the mAs must be increased by
Fibre Optics The principle of total internal reflection means incident light will ricochet from wall to wall along the insider of the conductor when what angle has been achieved
The critical angle
X-ray Tubes: If the cathode is heated and a potential of +35kV was placed on it while a potential of -35kV was placed on the anode, what direction would the current flow?
The current would flow from anode to cathode
Timers How does the pulse generator and pulse timer used in digital timer terminate the exposure
The digital timer counts the 'pulses' and when it reaches the number equivalent with the resent tie limit, it activates a signal to terminate the exposure
X-ray Tubes: In relation to x-ray tubes, what is referred to as the insert?
The glass encasing the anode and the cathode
Camera The effect in CCD and CMOS cameras that convert photons into electrons works on the basis that the higher the intensity of light......
The greater the number of electrons
Grids and Bucky's When using a focus grid: a. The stripe should be face down against the IR b. The grid must be used at a set distance c. An extremity IR should be used d. The grid can be angled in any direction
The grid must be at a set distance
Flat Panel Detectors Why is fill factor important during the spatial sampling of an image during digitisation
The higher the fill factor, the higher the contrast resolutions and the greater the spatial resolution
Grids and Bucky's The term grid ratio relates to
The relationship between the width of the interspace to its height
Filtration The greater potential difference across the cathode to the anode the.....
The smaller wavelength of the beam of radiation (greater wavelength = decrease kVp)
Camera Describe the term Fill Factor
The useable part of the pixel that contains the photodiode
X-ray Tubes: When referring to the focal spot size on the anode, a focal spot of 0.6mm refers to?
The width of the area bombarded by electrons
X-ray Tubes: When operating an x-ray system at 80kVp...
The x-rays produced will have a maximum energy of 80keV
Timers Which component energises the switching system and therefore terminates the exposure in electronic timers
Thyristor
Timers Which of the following is not a type of timer used in radiography a. Thyristor b. digital c. guard d. auto
Thyristor
Grids and Bucky's What is the primary function of a grid
To reduce scatter reaching the IR and degrading the image
Image Intensifiers If you were to change from a 400mm field of view to a 230mm field of view when using an II< the focal point would move....
Towards the input phosphor
Filtration TRUE or FALSE Increasing the kVp decreases the wavelength of the most intense x-rays
True
Television and Displays In an LCD screen, what process changes the direction of the backlight so that it can pass through the second polarising filter and illuminate the pixel
Twisted nematic effect
Collimators What is NOT a type of collimator a. single leaf b. multi leaf c. two tiered d. diaphragm
Two tiered
Fuses and Circuit Breakers If the fuse the controls the lights in your living room was to blow. It is one of the re-wireable fuses. The fuse has a rating of 15 A. If when you go to replace the fuse wire you find that you only have 20 A, 10A or 5A wires. What would be the safest thing to do?
Use some of the 10A fuse wire
Collimators Explain what Positive Beam Limitation means
Used senses in bucky tray to detect the size of the IR and send electronic signal to small motors in collimator which will adjust leaves/shutters and automatically collimate to the size of the IR
Camera Describe the term Electrostatic grid
Used to accelerate, deflect and focus the electron beam
Autotimers Changing the density step changes the ____ of the ____ required
Value, Electrical signal
X-ray Generator, etc What is required for a superconductor
Very low temp
X-ray Tubes: In Bremsstrahlung radiation production, the shortest wavelength is produced
When the electron is being deviated to the maximum around he nucleus
Flat Panel Detectors Explain what is meant by indirect conversion
When there are two steps to convert x-rays into an electrical signs 1st = converted to visible light 2 = converted to electrical signal
Collimators The collimators on a fluoroscopy unit are generally motor driven. So what statement is true? a. You can not adjust collimators to a field of view (FOV) larger than the size of the II. b. You can not adjust collimators to a FOV smaller than the size of the II. c. You can not adjust the vertical collimators to a FOV smaller than the size of the II. d. You can not adjust the horizontal collimators to a FOV smaller than the size of the II
a
Tube Ratings: Using the rating chart (with 500, 400, 300, 200, 100mA), what would be the safe exposure from the following: a. 70kV, 500mA, 01.sec b. 80kV, 300mA, 0.04sec c. 110kV, 400mA, 0.1sec d. 90kV, 400mA, 0.04sec
b.
Fuses and Circuit Breakers What does a Re-wireable fuse look like
block, with plate on top with a hole either end of the plate
Collimators What does a collimator NOT do? a. Define the size and shape of the x-ray beam emerging from the tube port. b. Minimises the area being irradiated and spares adjacent tissue from unnecessary exposure. c. Increases the penetration ability of the x-ray beam d. Leads to reduced scatter radiation, improving contrast resolution.
c. Increases the penetration ability of x-ray beam
Fuses and Circuit Breakers What does a Blade fuse look like
coloured fuses
Filtration What is NOT a reason for the use of aluminium as a filter: a. hardens the beam b. cheap and available c. efficient in removing low energy x-rays through photoelectric effect d. removed all high energy x-rays leaving only the low energy x-rays
d
Filtration What is NOT a type of filtration used in x-ray production a. additional b. compensatory c. inherent d. linear
d
Flat Panel Detectors Which of the following is true about spatial resolution? a. Used to describe the detail you can see b. Measured in line pairs c. Related to the size of the DELs d. All of the above
d. All of the above
Autotimers Which of the following statements about ionised air is true? a. It is resistant b. It is dangerous if inhaled c. It is the process by which free radicals are created d. It is electrically conducted
d. It is electrically conducted
Collimators Which of the following would an MRT be likely to alter first in order to prevent the production of scatter? a Reduce the kVp range b Reduce the amount of additional filtration c Reduce the body part thickness d Reduce the size of the collimated field
d. Reduce the size of collimated field
X-ray Generator, etc AC three phase electricity gives out _____ pulses per 1/50th of a sec compared to ___ pulses in single phase AC
six two
