Intro to Medical Signals and Systems

Question 1

Compare and contrast the different types of interferences (2)

Answer 1

1. Interfering
   - “noise”
   - quantities that inadvertently affect instruments by modifying the input
2. Modifying
   - quantities that alter performance of an instrument
   - can cause amplification and frequency “change how instrument works”

Question 2

How to classify biomedical instruments? (4)

Answer 2

1. Quantity that is sensed
2. Principle of transduction (method of converting output to electricity)
3. Organ system
4. Clinical medicine specialty
   - some systems are used for diff specialties

Question 3

Compare and contrast invasive vs non-invasive instruments

Answer 3

Invasive:
- puncture / incision of skin
- insertion of instrument / foreign material into body
(ex. laser eye treatment, CT scan)

minimally invasive:
- controlled, limited invasion (less invasive compared to alternative/ tradition techniques)

Question 4

Define accuracy

Answer 4

measure of deviation from actual value (high accuracy - less deviation)

+/- 1 digit for digital readouts
+/- 1/2 smallest division on analog scale

1. Full scale
   - normalizes reading to produce constant accuracy for all data points

A = (measured - actual) / max * 100

2. Of reading
   - has higher accuracy for specific data points and increases for others

A = (measured - actual) / (actual)

Question 5

Define precision

Answer 5

Number of possible measureable values
- high precision is NOT accuracy

Question 6

Resolution

Answer 6

Smallest measurable increment (with certainty)
- indicates degree to which nearly equal values can be distinguished

Question 7

Linearity

Answer 7

• measure of deviation from linear calibration curve over operating range

1. Up-scale readings (A) –> % of reading (varying accuracy; small is accurate, large is non-accurate)
2. small-scale readings (B) –> % full scale (constant accuracy)

Independent non-lienarity = +/- max(A,B)

Question 8

Repeatability (reproducitbility)

Answer 8

• ability to give same output for eaqual inputs over time
• repeatability is NOT accuracy

R = +/- (big - small) / (max)

big = biggest value obtained over n trials

small = smallest value obtained over n trials

max = max value over operating range

Question 9

Static Sensitivity

Answer 9

Measure of sensitivity of output to each input

Question 10

Zero + sensitivity drift

Answer 10

measure of deviation from calibration curve due to interfering and/or modifying inputs