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As stated in the Ionising Radiation (Medical Exposure) Regulations 2000 who is the person entitled to authorise an x-ray exposure? (1 mark)
Practitioner
Define contrast resolution. (1 mark)
Ability to distinguish and image similar tissues
Define the term half value layer. (1 mark)
The thickness of a material required to diminish the X-Ray beam by half
Describe 3 ways to reduce the amount of scatter reaching the image receptor (3 marks)
Use grid, tissue displacement, air gap
Describe how optimum image sharpness may be achieved with analogue radiography? ( 5 marks)
Small focal spot, decrease OFD, increase FFD, immobilisation, short exposure time
Does the level of tube current effect Radiographic contrast of an image? (1 mark)
No
Does tube filtration affect the quantity of x-rays reaching the image receptor? (1 mark)
No - the filtered x-rays would have been absorbed by the patient and therefore not reached the image receptor anyway
Explain 4 reasons for an analogue x-ray image being below optimum optical density assuming the processor is functioning correctly. (4 marks)
Incorrect exposure, Intesifying screen – speed too low, FFD increased, developer oxidised
Explain differential attenuation (2 marks)
Difference in amount of attenuation by absorption and scattering between different tissues, allows image to form
Explain how motion blur may be reduced when x-raying a difficult patient ( 5 marks)
Immobilisation/Good Communication/Short Exposure Time (ie Low mAs allowed by use of intensifying screen)
Explain how KvP will affect optical density on a radiographic image. (2 marks)
Increased production of photons in the transmitted beam (But contrast is affected also)
Explain penumbra. (3 marks)
Geometric unsharpness, image blur around the edges of an image. Focal spot not pin point, area determined from size of filament, results unsharpness, greatest effect spatial resolution
Explain the term differential attenuation (2 marks)
Difference in amount of attenuation (change in beam intensity) by absorption and scattering between different tissues as beam passes through material, allows image to form
Explain the function of a reflective layer in an intensifying screen (1 mark)
Reflect light back towards the film
Explain the term TR used in MRI.(1 mark)
Repetition time - time elapsed between successive pulses
Explain the use and importance of compensatory filtration. (2 marks)
Ability to image different thicknesses at once + reduce pt dose
Explain what is meant by the energy spectrum of an x-ray beam. (1 mark)
Range of energy levels within beam
Fluoroscopy, CT and MRI are all imaging modalities. Which use radiation to acquire the information for imaging? (2 marks)
CT and Fluoroscopy
Give 3 advantages of MRI. (3 marks)
No radiation dose, excellent visualisation of soft tissues, allows multiplanar visualisation
Give a definition of grid cut-off ( 1 mark)
Changes in image density due to the interaction with the grid
High energy radiation is scattered more than low energy radiation when interacting with matter. TRUE/FALSE (1 mark)
TRUE
How can an operator reduce image unsharpness when producing an analogue radiograph? (6 marks)
Small focal spot, slow screens, immobilisation, short exposure time, low kVp technique/ high contrast, low OFD, high FFD
How can scatter production be decreased within a patient? (3 marks)
Low kVp, collimation, tissue displacement (Also grid and air gap, but not ""within""
How can unnecessary patient dose be reduced? (6 marks)
Collimation, high speed screens, high kVp technique, good radiographic technique, communication, justification, protection, immobilisation if necessary
How does screen speed affect the exposure with analogue radiography (1 mark)
Increase screen speed – decrease exposure (dose)
How is magnification reduced when producing a radiographic image? (2 marks)
Large FFD, small OFD
How is the heel effect altered by the anode angle? (1 mark)
Steeper target, greater heel effect. Smaller angle = smaller focal spot
If a faster screen speed is used to decrease exposure time, what changes to the image quality occurs? (2 marks)
Poor resolution
If a radiograph film turns brown once it has been stored in the file room, what may be the problem? (1 mark )
FIXER not washed off properly, causes oxidation
If the OFD is increased what other factor should be changed to maintain image quality? (1 mark)
FFD
In practical terms when is half value layer information used? (1 mark)
Planning of x-ray room
Intensifying screens are routinely used in diagnostic radiography. List the advantages of this practice. (4 marks)
Less exposure so less motion blur and patient dose, decreased tube loading
Is infertility a non stochastic or stochastic effect of expose to ionising radiation? (1 mark)
Stochastic
Is the developer an acid or alkaline agent? (1 mark)
Alkaline
List 3 procedures an operator may use to reduce motion blur. (3 marks)
Decreased exposure time, good communication, patient position
List 3 ways an x-ray beam can be shifted to a higher average energy.(3 marks)
Tube filtration, high kVp, 3-phase frequency (or above) generator
List 5 options to obtain optimum image sharpness.(5 marks)
Small focal spot, decrease OFD, increase FFD, immobilisation, short exposure time
List the 2 reasons for restricting the x-ray beam. (2 marks)
Reduce unnecessary patient dose, reduce scatter and therefore improve contrast
List the 2 ways an x-ray beam can be shifted to a higher average energy. (2 marks )
Increase kVp, add filtration
List the types of fog that can occur on an x-ray film. (3 marks)
Scatter, Light, Chemical
Name 3 advantages of CR compared to analogue x-ray imaging ( 3 marks)
Image parameters can be manipulated easily, can zoom, easy to reproduce without loss of quality, easier storage
Name the type of crystals that are the main component of the x-ray film (1 mark)
Silver halide
Name the unit used for CT imaging (1 mark)
Hounsfield
Radiological image unsharpness *increases/decreases* as the object to receptor distance increases (1 mark)
Increases
Radionuclides emit x-rays True /False (1 mark)
FALSE
Shorter FFD’s result in _______________ heel effect (1 mark)
Increased
Should a patient who has a knee prostheses undergo an M.R.I. to image the knee joint and surrounding tissue? (1 mark)
Yes, if Titanium/non-magnetic substance
The ___ _______ the atomic number of a material, the greater the binding energy of a particular shell. (1 mark)
Greater
The smaller the projected focal spot, the __ _________ the image detail. (1 mark)
Better
What are the basic differences between Computed Tomography and Nuclear Medicine to image a patient? (2 marks)
Nuclear medicine primarily shows physiological function of a system, while CT produces a static image
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