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2. Foundations of Medicine PoD > Imaging/Diagnostic Techniques > Flashcards

Imaging/Diagnostic Techniques Flashcards

1
Q

define x-ray

A

a photographic or digital image of the internal composition of something, especially a part of the body, produced by X-rays being passed through it and being absorbed to different degrees by different materials

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2
Q

describe process of x-ray generation (briefly)

A
  • High energy electrons passed from 1 electrode to another
  • deflected down through patient to x-ray film
  • X-ray can then be viewed
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3
Q

what does intensity of x-rays vary with

A

tube current, antomic number of target, tube voltage

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4
Q

3 possible x-ray interactions with matter

A
  • scatter
  • transmission
  • absorption
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5
Q

attenuation

what increases it

A

process by which radiation loses power as it travels through matter and interacts with it
* inc with atomic number, density and thickness

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6
Q

attenuation coefficients

A

Air < Fat < Muscle < Bone < contrast agents/metal implants

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7
Q

why do different anatomical structures have different appearances on x-ray

A

different densities (and thus, attenuation)

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8
Q

describe the x-ray film

A

Luminescent screen - film emulsion - Luminescent screen

Emulsion contains silver halide; clumps form after exposure to light generated on luminescent screens

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9
Q

Ultrasound

A
  • Non-ionising as sound waves
  • use gel as can’t pass through air (doesn’t transmit)
  • echo transmitted back to probe
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10
Q

explain barium

A
  • radio-opaque contrast agent used for outlining the gastro-intestinal tract
  • high atomic number means absorbs more x-ray photons than surrounding tissues
  • declining use
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11
Q

explain computed tomography (CT)

A
  • rotating x-ray tube
  • multiple beams with single axis of rotation
  • digital geometry processing… axial image
  • often give iodinated contrast (intravenous, oral)
  • IV contrast can lead to kidney failure?
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12
Q

Applications of CT

A
  • trauma
  • cancer staging and response to treatment
  • guidance for procedures

Great for defining bony detail but exposure to radiation

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13
Q

ionising radiation and unit

A

particle/wave with sufficient energy to ionise a neutral atom/molecule and leave them with either a positive or negative charge - Sievert used to descibe the absorption of radiation by the human body

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14
Q

what can ionising radiation cause

A

cell damage:
* repair
* cell death
* mutating —> transformation

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15
Q

how to minimise radiation exposure

A
  • inc distance
  • minimise time exposed
  • use lead shield to protect staff/patients
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16
Q

fluroscopy

A

medical procedure that makes a real-time video of the movements inside a part of the body by passing x-rays through the body over a period of time

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17
Q

iodinated contrast media

A

drugs containing iodine that are given to patients to enhance the ability to see blood vessels and organs on medical images such as X-rays or computed tomography (CT) scans. Provide greater detail.

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18
Q

MRI

A
  • don’t show bone well but good with soft tissue
  • slower than CT
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19
Q

techniques used to diagnose and stage cancer

A
  • plain radiographs
  • barium studies
  • CT
  • MRI
  • PET
20
Q

functions of cross sectional imagine (e.g. CT, MRI, PET)

A
  • initial diagnosis and staging of dieseae
  • biopsy of the lesions
  • monitoruing response to treatment
  • evaluation of residual mass after treatment
  • recognition of complications of treatment
  • when there is concernt for disease relapse
  • treatment (minority of cases)
21
Q

CT and radiation

A
  • ALARA (as low as resonably possible)
  • ensure whether examination is necessary
  • adequate clinical inforation is essential for appropriate protocol
  • avoid repeat examinations
22
Q

MRI - how it works

A
  • strong magnetic field aligns protons in the body in one direction
  • radiofrequency pulse displaces protons and images created by displaing time take for protons to “relax” back to the original alignment
23
Q

MRI cons

A
  • claustrophobic and noisy
  • motion artefact
  • cannot image patients with pacmakers, aneurysm clips
24
Q

Screening

A
  • Diagnose disease at an earlier stage, before symptoms start
  • cancer is easier to treat and most likely to be curable
  • NHS screening programme Breast, Bowel, cervix
25
Q

purpose of screeing

A
  • test should detect disease at an early stage where treatment can alter outcome
  • test should cause no harm
  • test should have high sensitivity and specificity
  • benefit to the individual and the population should outweigh the cost
26
Q

scrrening for breast cancer

A

mammography

27
Q

MRI safety concerns

A

radiation: burns, hearing, muscle twitch…

28
Q

MRI contrast agents

A

Gadolinium DTPA is an IV contrast medium which causes changes in local magnetic field and so alters the tissue signal
Vascular lesions nd some tumours can be more easily seen

29
Q

why should be limit imaging investigations

A

can be expensive and should only bbe requested when appropriate

30
Q

what can inform the judicious use of imaging

A

guidlines

31
Q

what can help to decide which radiological tests
would be most useful to distinguish between diagnoses or between normal and abnormal

A

basic statistical concepts

32
Q

molecular imaging

A
  • Radionuclide imaging
  • Positron emission tomography (PET)
  • Magnetic resonance imaging (MRI)
  • optical imaging
33
Q

what do gamma rays occur from

A

radioactive decay of unstable isotopes

34
Q

what is molecular imaging

A

a field of medical imaging that focuses on imaging molecules of medical interest within living patients

35
Q

radionuclide imaging vs x-ray

A

diagnostic X-rays are used primarily to study anatomy. Nuclear imaging is used to study organ and tissue function

36
Q

properties of ideal isotope

A
  • half-life similar to length of examination
  • gamma emmitter (rather than a/B)
  • radionucleotide should be readily available at hospital site
  • easily bound to pharmaceutical component
  • energy of gamma rays should be 50-300 keV
  • radiopharmaceutical should be easy to prepare
  • radiopharmaceutical should be eliminated in similar half-time to duration of examination
37
Q

radiopharmaceutical

A

radioactive and pharmaceutical elements - designed to attach to part of body we are looking at

38
Q

gamma camera

A

an imaging device used to image gamma radiation–emitting radioisotopes

used in CTs?

39
Q

Single Photon Emission Computed Tomography (SPECT)

A
  • CT version of nuclear medicine
  • Gamma cameras rotate around area of interest
  • routinely used for brain and cardiac studies
  • can be applied to any site of interest in other studies (e.g. spine in bone scan or in lung scintigraphy)
40
Q

Positron Emission Tomography (PET)

A
  • molecular imaging
  • uses radionucleotides that decay by postiron emission (Proton —> neutron + positron)
  • These can be used to image biologically interesting processes
  • can be used for absolute quantitation but requires arterial sampling
  • all scanners now PET-CT
41
Q

PET and inflammation

A
  • rheumatoid arthritis
  • aortitis
  • ulcerative colitis
42
Q

Risks/benefits of radiation

A

Risk: ionising radiation - induce fatal cancer
Beneits: diagnosis, management change, treatement

43
Q

reasons to request laboratory investigations

A
  • Diagnosis (to rule in or rule out a diagnosis/ confirm/reject clinical diagnosis)
  • Monitoring (eg, the effect of drug therapy/ natural history or response to treatment)
  • Screening (detection of sub-clinical diagnosis)
  • Prognosis (prediction of course or outcome of the disease)
44
Q

individual laboratory medicine specialities

A
  • clinical biochemistry
  • immunology
  • microbiology
  • haematology
  • histopathology/cytopathology
  • genetics
45
Q

why is it important to adhere to laboratory sample acceptance policy

A

allows laboratory to produce the right result, on the right pateint, at the right time. Thus, allowing clinicans to give the right treatment in an timely manner. -good pateint care

vein to brain time

46
Q

examples of use of laboratory tests in the patient pathway

A

Basic Metabolic Panel (BMP)
Comprehensive Metabolic Panel (CMP)
Lipid Profile.
Thyroid Test(s)
Complete Blood Count (CBC) with or without White Blood Cell (WBC) Differential.
Prothrombin Time (PT) with INR & Activated Partial Thromboplastin Time (PTT)
Urinalysis (UA)

47
Q

pre-analytical errors that can contribute to erroneous electrolyte results - Vein to brain time?

not sure if right but gonna go with it

A
  • inadequate or incomplete requesting
  • issues with results not being seen in time or being icorrectly interpreted
  • issues with quality of control
  • interference/issues with analyser
  • sample not collected on system
  • delayed transit with unspun samples

2. Foundations of Medicine PoD (28 decks)

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