FYS 4250 Fysisk institutt Rikshospitalet Medical instrumentation intensive

FYS 4250 Fysisk institutt - Rikshospitalet

Medical instrumentation, intensive care unit FYS 4250 Fysisk institutt - Rikshospitalet

Operation room FYS 4250 Fysisk institutt - Rikshospitalet

Approaches • • Physicians Physicists, engineers Researcher Patients Functions: diagnostic, therapeutic, support Invasive / non-invasive Technology: electromagnetic, optical, mecanical FYS 4250 Fysisk institutt - Rikshospitalet

FYS 4250 Fysisk institutt - Rikshospitalet

Unit of measurement, SI system U = 5 volt U is the quantity 5 is the dimension figure [volt] is the unit Examples of non SI-units: bar, psi, inch, yard, degrees Fahrenheit, miles, gallon FYS 4250 Fysisk institutt - Rikshospitalet

Interfering modifying desired FYS 4250 Fysisk institutt - Rikshospitalet

Example: modifying, interfering input FYS 4250 Fysisk institutt - Rikshospitalet

Regulation systems of the body FYS 4250 Fysisk institutt - Rikshospitalet

Servo loop FYS 4250 Fysisk institutt - Rikshospitalet

Servo (negative feedback) Eq. 1. 3 y = output FYS 4250 xd = desired input Gd = gain Fysisk institutt - Rikshospitalet Hf = part of y back to input

Biostatistics • Sensitivity high • Specificity high FYS 4250 → → high true positive high true negative Fysisk institutt - Rikshospitalet

(a) Linear system fits the equation y = mx + b. (b) Nonlinear system does not fit the straight line. (a) FYS 4250 (b) Fysisk institutt - Rikshospitalet

(a) The one-point calibration may miss nonlinearity. (b) The two-point calibration may also miss nonlinearity. (a) FYS 4250 (b) Fysisk institutt - Rikshospitalet

A hysteresis loop The output curve obtained when increasing the measurand is different from the output obtained when decreasing the measurand. FYS 4250 Fysisk institutt - Rikshospitalet

Precision, (a) low, (b) high (a) FYS 4250 (b) Fysisk institutt - Rikshospitalet

Accuracy: (a) low, (b) high (a) FYS 4250 (b) Fysisk institutt - Rikshospitalet

Sensitivity Drifting FYS 4250 Fysisk institutt - Rikshospitalet

Linearity FYS 4250 Fysisk institutt - Rikshospitalet

Dynamic systems The medical variable to be measured will normally vary as a function of time The statical and dynamical properties of a measurement instrument can be described with a differeintial equation, usually limited to a 2. order like: a 2 d 2 y/dt 2 + a 1 dy/dt + a 0 y(t) = b 2 d 2 x/dt 2 +b 1 dx/dt + b 0 x(t) input x(t), FYS 4250 output y(t) Fysisk institutt - Rikshospitalet

0. order system, static, no energy storing FYS 4250 Fysisk institutt - Rikshospitalet

1. order system, one energy storing element, relaxation FYS 4250 Fysisk institutt - Rikshospitalet

2. order system, two energy storing elements, swinging system FYS 4250 Fysisk institutt - Rikshospitalet

2. order system, blood pressure monitoring FYS 4250 Fysisk institutt - Rikshospitalet

Teknology: How to Design, construct Produce, market Medical equipment FYS 4250 Fysisk institutt - Rikshospitalet