basic radiological imaging

Question 1

Digital images are stored as a series of — in a computer memory where they are represented by a —- whose —- or — corresponds to the — of the object at a specific location

Answer 1

• pixels
• square box
• intensity or brightness
• brightness

Question 2

• a —- or —- which consists of 2d or 3d array
• each element in the array corresponds to a specific — within the patient ( this region needs to be studied )
• each element of the array has a —- and/or — value assigned to it which is defined by —- which depend on —– as:

Answer 2

• template or computer generated grid
• physical location
• color and/or brightness
• the user
• measured parameter as : absorption . emission of radiation

Question 3

all non visuals or computerised medical imaging carry out the following simple procedure which is:
1- —- what is to be imaged
2- apply the appropriate —-
3- measure the received signal as a function of —–( Each element of the matrix corresponds to a physical position within the region of study , The numerical value of each matrix element represents the strength of the signal received at that position.)
- a —–is defined by the user whereby colours or grey scale is assigned to each numerical value

Answer 3

• identify
• technology
• function of location
• color scale

Question 4

ionising radiation needs to have :
1- frequency :
2- photon energy :
3- wavelength
and they will break bonds and cause electrons to be —

Answer 4

• more than 1 x 10 power 15
• more than 4ev
• less than 300 nm ( uv)
• free
  ( check slide 9 )

Question 5

1-X-rays have — d images and they are —- equally well by all materials
2- heavy elements as — are — absorbers of x rays while lighter elements are — absorbers of x rays
3- since x rays can be blacken photographic film , —- can be produced when a body is placed between — and —-

Answer 5

• 2d
• not absorbed equally
• calcium
• good absorbers
• not absorbed well
• shadow pictures
• x ray source and photographic film

Question 6

—– are electromagnetic radiation (photons) of high energy (10-100 keV).
these rays of different energies are produced by bombarding a material w —-

Answer 6

• x rays
• electrons

Question 7

1-x rays can interact w atoms in tissue and creates tissue —- aka —-
2- when they are transmitted/detected
3- when they are absorbed/atteunated
4- when they are scattered/detected

Answer 7

• contrast aka artefacts
• are dark and have no interaction
• are bight and have photo-electric
• are artefacnt/blurring as Compton
  ( check image slide 13 )

Question 8

1- muscle , fat and tumours are examples of – tissues and all have —-absorption characteristic for x rays and therefrom — to distinguish in standard x ray
2- —- of an x-ray beam is the reduction in its intensity due to the absorption and/or scattering of some of the x-ray photons out of the beam (note: Lambert-Beer Law).
3- the main contrast between :
4- better contrast at:
5- less scattering at — which leads to — and less —-
5- higher energies needed for —

Answer 8

• soft tissue
• attenuation
• bone and other tissue
• at lower x ray energies
• less scattering at lower x ray energies which gives netter quality image and less artifacnt
• higher energies needed for deeper penetration ( check graph important slide 15)

Question 9

2-d x rays are commonly used to detect —

Answer 9

bone fractures

Question 10

-DEXA is a — technique which is used to determine the – of the bone hence its —–
- its considered to be a gold standard method for diagnosing —-
- DEXA measures —- and —–

Answer 10

• scanning
• density
• mechanical strength
• osteoporosis and fracture risk
• bone mineral density BMD and is commonly used for hip and lumbar spine but also other bones

Question 11

-DEXA works by sending —– which are absorbed differently by —- and —
-The ratio of the attenuation coefficients from these X-ray beams are used to calculate —-
- lower the density =
- DEXA is — and takes — and the amount of radiation is — about — of normal chest x ray

Answer 11

• 2 low dose x ray
• bones and soft tissue
• bone mineral density BMD
• greater risk of fracture at low density
• painless
• 10 minutes
• very low
• 10%

Question 12

-bone densities are often given to a patient as —- or —
- your BMD is compared to – which is:
1- healthy young adult aka :
2- age matched adult aka:
- your BMD is compared w the BMD results from large sample of healthy —- adults of same —- .
- T score is given as the number of — between – and — of the same group
- postive t score idnicates :
- negative t score indicates

Answer 12

• t score or z score
• t score
• z score
• 25-35 yo
• sex and ethnicity
• standard deviation (SD) between your BMD and BMD of the sample group
• your bones are stronger than normal
• bones are weaker than normal

Question 13

1- Bone density is within 1 SD (+1 or −1) of the young adult mean indicates —-
2- Bone density is between 1 and 2.5 SD below the young adult mean (−1 to −2.5 SD) indicates —
3- Bone density is 2.5 SD or more below the young adult mean (−2.5 SD or l
lower) indicates —-
4- Bone density is more than 2.5 SD below the young adult mean, and there have been one or more osteoporotic fractures indicates —-

Answer 13

• normal
• low bone mass
• osteoporosis
• severe ( establisehd ) osteoprosis

Question 14

the risk of bine fracture – w every SD below normal.
the person w BMD of 1SD below normal ( t-score of -1) has – the risk for bone fracture as a person w normal BMD . when this info is known ppl w high risk for bone fracture can be treated w goal of preventing future fractures

Answer 14

• doubles
• twice

Question 15

—- is that the structure of an object can be ‘reconstructed’ from a series of x-ray projections taken uniformly around the object.
consider a thin pencil beam of – passing through a section of tissue w many —– so that the beam have a —-

Answer 15

• CT ( computerised tomography )
• x rays
• different directions
• common crossing point

Question 16

-From all these projections CT calculates (=computes) the ——
- significant gain in —-
- signal independent of —

Answer 16

• attenuation in each voxel / tiny volume (=3D information)
• tissue contrast and resolution
• tissue thickness

Question 17

in ct scan:
1-a — array is constructed by a computer
2- each element of array corresponds to a specific — within the patient under asessemnt
3- a — assigned to each element corresponds to the — at the location
4- a — is developed whereby a specific color or greyscale is assigned to particular values of —
5- computer paints by —
6- — is constructed

Answer 17

• 3d
• location
• numerical value
• calculated absorption ( using lac’s from each projection )
• color scheme
• absorption
• numbers
• image

Question 18

In —– machines, the patient slides through a circular ‘gantry’ containing x-ray sources and detectors, creating a spiral motion, creating many x-ray projections.

Answer 18

modern ct machines

Question 19

ultrasound is — and — of using —- waves to look at parts of human anatomy
the technology work on principle similar to —

Answer 19

• safe and painless
• sound waves
• sonar

Question 20

1-We know the — of the ultrasound, so measuring the —- taken to detect a reflected ultrasound wave, allows us to calculate the —- to the reflective boundary
2-The intensity of the reflected ultrasound wave tells us about the —- of the reflecting medium

Answer 20

• speed
• time
• distance
• density so image can be formed
  ( check slide 33 important )

Question 21

true or false:
Musculoskeletal ultrasound allows physicians to see, in high resolution, a person’s muscles, tendons, ligaments, nerves and joints,“ (Yale Medicine radiologist)

Answer 21

true

Question 22

Proton spins within water molecules become aligned to the very strong magnetic field which exists within the ‘bore’ of the —-
1——- (=electromagnetic radiation/photons of ultralow energy, <1 µeV) are used to perturb the alignment of proton spins and their dynamic return to equilibrium
2- gradient coil produce changing —- along different directions needed to probe signals at different location ( >3d info )
3- are — and —

Answer 22

MRI machine ( physics of underlying MRI is complex )
- Short radiofrequency pulses
- magnetic field
- non invasive and harmless

Question 23

-Proton spins from different tissues return to their —- states at different rates – a difference that can be detected.
measurement of the recovery times include:

Answer 23

• equilibrium
  -Spin-LatticeRelaxation or T1, and Spin-Spin Relaxation or T2) allows us to distinguish (contrast) between different tissue types.

Question 24

mri provded better soft tissue contrast than —

Answer 24

CT
- info:
1- Provides good contrast between gray matter (dark gray) and white matter (lighter gray) tissues, while CSF is void of signal (black).
2- Provides good contrast between CSF (bright) and brain tissue (dark).