MC Lec1-3 Flashcards
true or false: the hypothetico-deductive approach is an iterative process for medical data collection and interpretation
true
true or false: in the hypothetico-deductive approach, information is collected only initially and is built upon via medical knowledge in a heuristic manner
false: generation and collection of data happens multiple times
true or false: in hypothetico-deductive approach, initial hypothesis is not made until a variety of medical data types is inputted
false: hypothesis is refined multiple times as information is gathered
true or false: the hypothetico-deductive process is inherently knowledge-based and requires interpretation of data and selection of appropriate follow-up questions/tests
true
the two most central features of the hypothetico-deductive approach are:
gathering data and interpreting the meaning
list the five major medical data types:
- narrative/textual data
- numerical measurements
- recorded signals
- drawings
- photographs/images
which of these is NOT a use of medical data?
a) adds to medical history records
b) all of these are
c) supports clinical research
d) identification of disease trends or deviations
e) identify preventative measures
f) medical communication among providers
b
what is medical thermology imaging?
a) 2D representation of the heat radiation from the body via a thermal camera
b) Planar representation of the heat radiation from the body via a thermal camera
c) 3D representation of the heat radiation from the body via a thermal camera
d) Any of the above are referred to a thermal imaging
a
what is medical transillumination imaging?
a) shining near infrared radiation through part of the body and viewing the transmitted radiation
b) shining visible light through part of the body and viewing the transmitted radiation
c) shining visible light or near infrared radiation through part of the body and viewing the transmitted radiation
d) Any form of imaging that utilises a screen such as an x-ray or CT
c
which of these is not a benefit of medical endoscopy imaging?
a) minimally invasive
b) obtain samples
c) real-time
d) can before surgical procedures
d
the amount of x-ray absorbed is proportional to:
a) current used to generate x-ray
b) tissue composition of hydrogen ions
c) tissue density
d) voltage used to generate x-ray
c
true or false: conventional x-rays utilise an x-ray detector rather than film
false: this is a digital x-ray
true or false: x-rays are generated via accelerated protons colliding with the nuclei of a heavy metal to generate photons
false: it is electrons accelerated
true or false: digital x-rays utilise a charged-couple device and a thin-film transistor to convert light from phosphor to a digital signal
true
true or false: conventional x-ray images can be stored, transmitted, and manipulated
false: this is digital x-rays
digital mammographs use:
a) small low doses of ionizing radiation in the form of an x-ray
b) small high doses of ionizing radiation in the form of x-rays
c) high low doses of ionizing radiation in the form of an x-ray
d) high high doses of ionizing radiation in the form of an x-ray
a
true or false: a voxel represents a volume + pixel which enables us to describe resolution
true
true or false: bones will have a higher attenuation and thus lower voxel score compared to fluids
false: higher attenuation and HIGHER voxel score
the scale in which we use to explain CTs is:
Hounsfield Attentuation Scale (HU)
the Hounsfield scale is:
a) 100 units wide
b) 400 units wide
c) 1000 units wide
d) 2000 units wide
d
true or false: water has a value of 0HU
true
true or false: bone has a value of 1000 on the HU scale
false: 400+
true or false: air has a value of 0 on the HU scale
false: -1000
name the three components of a CT machine:
linear patient, X-ray source, sensing ring
true or false: the sensor is perpendicular to the x-ray source in CT
false: its opposite to it (parallel)
the information received at the sensor must be processed by ____________
ART (algebraic reconstruction techniques)
ART:
a) transform planar images into a digital 2D volume in CT
b) transform planar images into a digital 3D volume in CT
c) is used in x-rays to convert them to digital
d) is used in all modalities
a
true or false: In CT, the patient is perpendicular to the sensor ring
true
MRI uses a ________ field to align the magnetic field of _____ which are predominately found in ______.
magnetic, protons (hydrogen ions), water
what is the order of MRI?
1) a strong magnetic field is applied to hydrogen ions in water
2) protons absorb energy from the magnetic field which flips their spin
3) the reduction in energy is emitted as a radio signal that can be measured and amplified by receivers
4) when the field is turned off, the protons gradually return to their normal spin known as ‘precession’
1243
structures of the body are identifiable in MRI via:
a) energy released
b) spin speed
c) realignment speed
d) all of the above
c
true or false: MRI requires no moving parts, it is completely electronic
true
T1 weighting is used for:
a) anatomy/learning
b) pathology
c) both
a
T2 weighting is used for:
a) anatomy/learning
b) pathology
c) both
b
in T1 weighting, fluids are _____, water-based tissues are ______, and fat-based tissues are _______
dark, mid-grey, bright
in T2 weighting, abnormal fluids are _____, water-based tissues are ______, and fat-based tissues are _______
bright, mid-grey, dark
in T2, repetition time, and echo time are
a) increased
b) decreased
c) neither
a
repetition time and echo time control:
a) sensitivity of the signal
b) relaxation time
c) local proton density
d) all of the above
d
Ultrasound imaging is best used for:
a) distinguishing solid and fluid masses
b) anatomical variations
c) pathology
d) soft organs
a
positron emission tomography works by observing the behaviour of an administered substance known as a ______ with a radioactive element known as an _____
tracer, isotope
in PET, images are formed via the detection of ______ from a radioactive tracer which emit ____ that are detected by scintillation crystals
positrons, photons
true or false: PET offers quantitative analysis with respect to time
true
list the order of PET:
- the positron collides with an electron in tissue, releasing two photons
- crystals absorb photons, producing light that is converted to an electrical signal
- the PET camera uses scintillation crystals to detect photons
- the nucleus of a radioisotope emits a positron
4132
what is the main difference between SPECT and CT?
a) imaging processing
b) source of radiation
c) detection method
d) all of the above
b (SPECT = gamma, CT = x-rays/photons)
true or false: the signal in SPECT is the attenuation of gamma rays from the emitting nuclei to the detector
true
when would you use SPECT over regular CT?
a) pathologies
b) brain imaging
c) cardiac imaging
d) all of the above
c
the result of sampling and quantization is:
a) a digitized image
b) a matrix of real and complex numbers
c) a digitized scan line
d) a matrix of real numbers
d
each element of the matrix array is called all but:
a) image element
b) picture element
c) pel
d) pixel
e) voxel
e
true or false: grey-scale resolution refers to the largest, discernible change in grey level
false: smallest discernible
reconstruction from projections is:
a) image restoration of a 3D object reconstructed from several 2D projections
b) image restoration of a 2D object reconstructed from several 1D projections
c) image restoration of a 2D object reconstructed from several 2D projections
d) all are true
b
the algebraic reconstruction technique is used in what modality:
a) x-ray
b) CT
c) PET
d) MRI
e) all of the above
b
the four angles in CT are:
0, 45, 90, 135
true or false: in ART, the 2D image is reconstructed using a matrix inversion of the projection data
true
which of these is not a difficulty of medical image acquisition?
a) accessibility of organ of interest
b) patient consent
c) variability of information
d) physiological artifacts
e) energy limitations
f) patient safety
b
contrast is defined as:
the difference between the region of interest and a suitably defined background
the formula for normal contrast and simultaneous contrast are:
Cn = (f-b)/(f+b)
Cs = (f-b)/b
true or false: contrast depends on the intensity of the region of interest AND background and is a ratio
true
true or false: mach bands have the same intensity, but it appears brighter particularly in the middle of the bands
false: appears brighter at the band boundaries known as ‘scalloped bands’
true or false: mach bands demonstrate that brightness is a simple function of intensity
false: human visual system over or undershoots
the human visual system has:
a) high-filter characteristics
b) low-filter characteristics
c) band-pass characteristics
d) all of the above
c
true or false: the human visual system is more inclined to observe proportional differences between illumination levels rather than absolute illumination levels
true
which formula demonstrates how background colour can attenuate the human visual system’s perception of contrast?
a) simultaneous contrast (Cs=(f-b)/b)
b) normal contrast (Cn=(f-b)/(f+b))
c) optical density (Cod=Fod-Bod)
d) all of the above as they are all contrast equations
a
true or false: simultaneous contrast is on a scale of [-1, +1] which is advantageous
false: normal contrast is on a scale of -1,+1
Just-Noticeable Difference describes the minimal ______ of an object relative to the background level, _
perception, b
true or false: Weber’s law states that the JND will almost always be a constant of 2% (0.02) over a wide range of background intensities
true
the three key components of data processing and analysis is:
contrast, histogram, noise
a histogram gives _____ grey levels and provides an _____ profile of an image. Histograms can be viewed as a probability ______ function.
discrete, intensity, density
list two sources of noise:
interference from environment or machinery, motion artifact of organ
what are the three types of noise noted:
salt and pepper: random occurrence of black and white pixels
impulsive noise: random occurrence of white pixels
gaussian noise: variations of intensity from normal distribution
spatial domain processing techniques are based on:
a) direct manipulation of pixels
b) linear transformation of pixels in a neighbourhood
c) modifying the fourier transform of an image
d) non-linear transformation of pixels in a neighbourhood
a
frequency domain processing techniques are based on:
a) direct manipulation of pixels
b) linear transformation of pixels in a neighbourhood
c) modifying the fourier transform of an image
d) non-linear transformation of pixels in a neighbourhood
c
true or false: in spatial domain processing, the operator T is defined over some neighbourhood
true
true or false: spatial domain processing is also referred to as pixel group processing, mask processing, and smoothing
false: filtering not smoothing
the main difference between spatial domain image processing and pixel point processing is that spatial domain takes into consideration the surrounding pixel neighbours to generate a new value
true
true or false: pixel point processing is a transformation function where the operator T becomes a grey-level transformation function that generates a new value solely based on the old value
true
true or false: a non-linear equation is proven true if the operator applied to the sum is identical to the operator applied to the images individually
false: this is a LINEAR equation
true or false: function curves represent and control different attributes of an image such as brightness and colour. the image must be retouched with a retouching tool in order to do so
false: manipulating the function curve enables the alteration of the image directly without a retouching tool
grey level transformations involve ______ curves
function
in grey level transformations, the equation s=T(r) is used to process values of a pixel. what does each letter stand for?
s=new pixel value
T = transformation that maps the old pixel to the new pixel
r = new pixel
how are grey level transformations implemented?
table lookups
list the five types of grey level transformations
- linear (negative and identity)
- log (log and inverse-log)
- power-law (nth power and nth root)
- window-level operation
- pseudo-colour
which of these is image negatives (linear transformation GLT) most useful for?
a) when the region of interest is dense in low-grey/dark values
b) enhancing white or grey detail embedded in dark regions
c) when you want to increase the contrast in dark areas and decrease the contrast in bright areas
d) all of the above
b
which of these is log transformation most useful for?
a) when the region of interest is dense in low-grey/dark pixels
b) enhancing white or grey detail embedded in dark regions
c) when you want to increase the contrast in dark areas and decrease the contrast in bright areas
d) all of the above
a
which of these is power-law transformation most useful for?
a) when the region of interest is dense in low-grey/dark pixels
b) enhancing white or grey detail embedded in dark regions
c) when you want to increase the contrast in dark areas and decrease the contrast in bright areas
d) all of the above
c
how does power-law and log-transformation differ?
in power-law, can create a family of possible transformations by altering gamma value (s=cr^gamma)
true or false: reducing the gamma value in power-law transofrmations will enhance brighter pixels, but can reduce contrast and cause a washout effect
true
in window-level operation, contrast outside the window is not lost, but the contrast inside the window is stretched to take up the entire grey level range
false: the contrast outside the window is COMPLETELY lost
true or false: window-level operation may be useful for highlighting an intensity band of interest
true
if window=0 in window-level operation, we get ______ _______ ________
binary image thresholding. because there is no gradient, it is black or white (hence binary)
true or false: some imaging modalities can capture colour
false: they are acquired and displayed in greyscale and colour can be added
why is colour useful?
humans are able to discern multiple shades, intensities, and variations in colour; whereas we can only discern about two dozen shades of grey - mach bands/contrast reference
intensity slicing coding involves the application of ______ to a greyscale image. an image must be interpreted as a 3D function of _____ against spatial coordinates. a slicing plane is _____ to the x-axis and assigns a colour whose grey level is _____ the plane.
colour, intensity, parallel, above
true or false: we can stretch colour ranges if a lot of the features are not within a particular range
true. see slide 53 lec 3
true or false: stretching the colour range will allow us to view more features on an image
false: we show less of the range and we can see more structures
temporal subtracts subtracts images in a ______ way:
a) pixel-wise way
b) intensity
c) greyscale
d) all of the above
a
when would you use temporal subtraction?
to get rid of the background in two similar images i.e. angiography of blood vessels
temporal average adds images in a pixel-wise way. when would you use temporal averaging?
to cancel out noise of a motionless object (NOT artifacts)
true or false: in histogram transformation, images whose pixels tend to occupy the entire range of possible grey levels and tend to have uniform distribution will have high contrast and limited grey tones
false: high contrast and a LARGE VARIETY of grey tones.
histogram equalization increases the ______ in an image by _____ the histogram to approximately uniform distribution
contrast, stretching
true or false: the image that has been histogram equalized ALWAYS has pixels that reach the brightest grey level
true
true or false: histogram equalizers are a form of spatial processing imaging
false: transformation imaging
the main point of histogram equalization is:
a) better enhancement of darker regions
b) better contrast
c) better grey scale distribution
d) better brightness
b
true or false: spatial filtering takes into consideration the size of the neighbourhood which is spanned by the filter mask
true
what are smoothing filters (spatial filtering) used for?
a) enhancement of darker regions
b) motion artifact reduction
c) enhance contrast
d) blurring and noise reduction
d
which of these is NOT a linear smoothing filter?
a) median filter
b) box filter
c) weighted filter
d) all of the above are linear smoothing filters
a
which of these is NOT a non-linear smoothing filter?
a) median filter
b) max filter
c) min filter
d) weighted filter
e) all of the above are
d
box filters and weighted average filters are a type of linear smoothing filter which can be referred to as __________
averaging filters
true or false: in a box filter, a spatial averaging filter will render all coefficients of different values
false: all coefficients are equal
true or false: a weighted average filter involves the multiplication of pixels by different coefficients to give more importance to some pixels than others
true
a median filter is a order-specific smoothing filter (non-linear spatial filter). the principal function is to:
a) to apply the median value in a neighbourhood to all pixels of that neighbourhood
b) to utilise the median value as a normalizer
c) force points with distinct grey levels to be more like their neighbours
d) to have preferential weighting of some pixels over others
c
