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Lab Instrumentation1
Exam 1
Question | Answer |
---|---|
3 factors that contribute to the cost of automation | maintenance, personnel training, analyzer cost |
lab characteristics used to justify the cost of automation | lab size, workflow, specimen volume, safety advantages |
Ordering automation | electronic orders, standing orders, generated bar-codes with important patient info |
Transportation automation | P-tube, track systems |
Receiving automation | LIS |
Reporting results automation | can go directly into clinician electronically, results can go to medical records to be apart of patients chart |
Maintenance of quality across all aspects of the testing process | quality assurance |
purpose of quality assurance | to evaluate the system and prevent errors |
Which phase of testing accounts for the most laboratory error and why | Pre-analytical because there's less automation for this and we see an increase with human error |
What is the purpose of quality control material | provides us with insight on how the analyzers are functioning and the accuracy of the test results |
why liquid QC over lyophilized | more stable and decreases pipetting errors during reconstitution |
analyzed by the manufacturer so the concentration of the analyses they contain is known | assayed QC |
concentration of the analyses is unknown and must be determined by the lab | unassayed QC |
When is it necessary to repeat QC material | maintenance is done, something is suspected to be wrong, reagent lot change, major component replacement |
A sudden change due to an analyzer malfunction | shift |
a gradual change due to reagent deterioration | drift |
What steps do you need to take in evaluating a failed QC run | rerun once, ask questions, contact service technician if problem is not resolved |
concentration of a substance is proportional to the amount of light absorbed | beers law |
measures the intensity of light at selected wavelength | absorbance spectrophotometry |
two factors that quantitative measurement using absorbance spectrophotometry depend on | color, intensity of the color |
examples of monochromator in modern technology | filters, prism, grating |
two types of photoelectric cells | barrier layer cell, photomultiplier tubes |
measure light reflected from the surface of a colorimetric reaction | reflectance spectrophotometry |
Name the layers in dry-slide technology | spreading, scavenger, reagent, indicator, support layer, spectrophotometer |
sample is distributed evenly | spreading layer |
filters out substances that could interfere with results | scavenger layer |
reagent reacts with sample | reagent layer |
reacted sample collects for spectral analysis | indicator layer |
optical interface | support |
measures the absorption of light by an element in its ground state | atomic absorption spectrometry |
example of a lab test performed using atomic absorption spectrometry | determining blood lead levels |
Valence electrons from some substances are able to absorb light energy, exciting the electron, electron returns to ground state and gives up energy as a photon of light which results in a fluorescence emission | fluorometry |
compounds that can re-emit light upon excitation; produces color in testing | fluorochromes/fluorophores |
commonly used fluorescent dye in the lab | fluorescein isothiocyanate (green) |
two ways light scatter is measured | turbidimetry, nephelometry |
Which form of light scatter is more sensitive | nephelometry because more light is scattered than transmitted |
the measurement of the reduction of light transmitted through a solution caused by particle formation | turbidimetry |
test done by turbidimetry | PT/INR; clot formation |
the measurement of scattered light by a particulate solution | nephelometry |
lab test performed by nephelometry | antibody-antigen reactions (rheumatoid factor) |
impedance-based technology that is used to analyze cells | flow cytometry |
Four main component of a flow cell cytometer | cells, illumination, fluidics, detectors/electronics |
sample cell suspension is injected into the center of a rapidly flowing stream to pass the sample through the analysis point one at a time | hydrodynamic focusing |
what is forward scatter | lenses collect light and focus it on a photodiode and the light is converted to electrical current; measures cell size |
what is side scatter | uses wavelength-specific mirrors and filters to transmit light specific to the wavelength of the dye that is used; measures cell complexity |
lab test performed by flow cytometry | immunophenotyping cells |
radiation detector that counts radioactive labels | scintillation counter |
disadvantages of RIA | lot of radioactive waste, short shelf life of radioactive isotopes |
what replaced RIA | Chemiluminescence |
what are immunoassays used to measure | antibody-antigen reactions |
liquid phase and require no wash step, competitive format | homogenous assay |
has solid phase, requires a wash step and can be competitive or non | heterogenous assay |
3 categories of immunoassay labels | enzymes, fluorogens, chemiluminescent |
What are the two main classifications of radiation | ionizing and non |
examples of ionizing radiation | microwave and radio |
examples of non-ionizing radiation | x-rays and gamma |
difference btwn electromagnetic radiation and particulate radiation | electromagnetic carries no charge while particulate are charged particles (alpha and beta) |
what makes an atom radioactive | unbalanced protons and neutrons = unstable nucleus |
Three types of decay an atom can undergo | alpha, beta, gamma |
unstable nucleus gives up 2 protons and 2 neutrons which leads to an atomic mass and number change | alpha |
ejects and electron, converting a neutron to a proton which leads to an atomic number change but the same mass | beta |
what would stop alpha radiation | paper |
what would stop beta radiation | block of wood |
what would stop gamma radiation | lead |
what type of radiation is emitted from a patient undergoing testing in nuclear medicine | gamma |
four examples of how we use radiation in the clinical lab | radioimmunoassays, x-rays, MRI, CT |
what assay is used in the echo analyzer | capture assay |