BME 455 Quiz 1 (23 Questions and Answers)
Light and Photons are used to describe the same physical phenomenon, i.e., optics, please briefly explain this duality feature based on your understanding with one example of each ** Answ**
BME 455 Quiz 1 (23 Questions and Answers)
Light and Photons are used to describe the same physical phenomenon, i.e., optics,
please briefly explain this duality feature based on your understanding with one
example of each ** Answ** There is a wave-particle duality to light. This means that
at times light can behave like a particle (a photon) and other times it may act as a wave.
An example of the particle description is when a photon collides with a molecule during
absorption or scattering. An example of its wave like nature is when light can reflect or
pass through certain objects.
What is "biomedical optics" and what is "tissue spectroscopy" ** Answ** Biomedical
optics: design and application of optics science and technology to biomedical problems.
Tissue spectroscopy: The study of tissue samples by the measure of their wavelength-
dependent interactions with light
Please explain what condition needs to be met to allow the optical absorption to occur
during the interactions of light and a given molecule. ** Answ** The energy of the
photon must match the change in energy needed to excite the valence electron to a
higher energy level in order for absorption to occur.
delta E (molecule)= E(photon)=hf
Describe the famous law with equation that is commonly used for absorption
measurement. How can one modify this equation to quantify the tissue vascular oxygen
saturation ** Answ** Beer's Law: A=log10(I0/I)=ecl
Beers law can be modified to calculate the concentrations of hemoglobin and
deoxyhemoglobin. This information can then be used to calculate and compare
hemoglobin saturation to the pressure of oxygen in the blood.
Please provide the definition of the two commonly used optical properties parameters
** Answ** Absorption: Photon energy is absorbed by molecule and valence electrons
are excited to a higher energy state
scattering: light photons bump into molecules in a solution and are deflected in different
directions
Can you draw the design of a simple optical system to quantify absorption of liquid
solutions and explain how can you use such a system for the absorption quantification?
** Answ** monochromator- sample chamber- detector.
Measure the light intensity before and after passing through the sample using a
baseline reference. Can then use Beers law to find Absorbance
For assistance with assignments contact informationhimher@gmail.com
, Can you describe the two major tissue vascular parameters that optical techniques can
quantify and explain why they are important for tumor biology study? ** Answ**
Tumor Hypoxia: inadequate oxygen supply to the tissue. Important to study because
can be useful in identifying where tumors are, and can help determine aggressiveness
of tumor.
Angiogenesis: process through which new blood vessels form from pre-existing vessels,
formed in the earlier stage of vasculogenesis. Important to study because can help us
locate aggressive tumors
Both are useful to monitor when researching different treatments in vivo
Please explain what condition needs to be met to allow the optical scattering to occur
during the interactions of the light and a given media? ** Answ** heterogeneities in a
bulk media. These cause photons to bounce off particles in the media, causing
scattering to occur.
There are two types of elastic scattering. can you describe each of the two types and
give a real life example? ** Answ** rayleigh: scattering from small particles,
scattering all around not just forward. Ex. Blue sky from light hitting N and O molecules.
Mie: scattering from large particles, primarily forward scattering, Ex. White clouds from
light hitting large water molecules.
Why is the cloud white and the sky blue? ** Answ** White clouds from light
scattering off large water molecules (mie), blue sky from light scattering off small N and
O molecules (rayleigh)
What is the motivation for tissue optics? ** Answ** Build a optical device for fast,
non-invasive and accurate detection of tissue physiology/pathology/ function.
There are three ways to solve the equation of radiative transfer in tissue optics. Can you
briefly summarize them and discuss their pros and cons? ** Answ** Numerical
Techniques, Diffusion Approximation, Monte Carlo Simulations
Numerical Techniques plus pros and cons ** Answ** discretization of equation,
finite-difference and finite element method. Difficult to implement, computationally
intensive, accuracy depends on discretization
Diffusion Approximation (and pros and cons) ** Answ** approximating ERT to find
simple partial differential equations.
easy to implement, faster results, limited accuracy
Monte Carlo Simulation ** Answ** stochastic solution methods, many single photon
are randomly propagated, indirect solution of inegro-differential equations.
easy to implement, very time consuming, very accurate
For assistance with assignments contact informationhimher@gmail.com
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