FYS4250Fysisk institutt - Rikshospitalet FYS 4250

Fysisk institutt - Rikshospitalet Medical instrumentation, intensive care unit

FYS4250Fysisk institutt - Rikshospitalet Operating room

FYS4250Fysisk institutt - Rikshospitalet Approaches Physicians Physicists, engineers Researcher Patients Functions: diagnostic, therapeutic, support Invasive / non-invasive Technology: electromagnetic, optical, mecanical

FYS4250Fysisk institutt - Rikshospitalet

FYS4250Fysisk 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

FYS4250Fysisk institutt - Rikshospitalet Interfering modifying desired

FYS4250Fysisk institutt - Rikshospitalet Example: modifying, interfering input

FYS4250Fysisk institutt - Rikshospitalet Regulation systems of the body

FYS4250Fysisk institutt - Rikshospitalet Servo loop

FYS4250Fysisk institutt - Rikshospitalet Servo (negative feedback) Eq.1.3 y = output x d = desired inputG d = gain H f = part of y back to input

FYS4250Fysisk institutt - Rikshospitalet Biostatistics Sensitivity high → high true positive Specificity high → high true negative

FYS4250Fysisk institutt - Rikshospitalet (a)(b) (a) Linear system fits the equation y = mx + b. (b) Nonlinear system does not fit the straight line.

FYS4250Fysisk institutt - Rikshospitalet (a)(b) (a)The one-point calibration may miss nonlinearity. (b)The two-point calibration may also miss nonlinearity.

FYS4250Fysisk institutt - Rikshospitalet A hysteresis loop The output curve obtained when increasing the measurand is different from the output obtained when decreasing the measurand.

FYS4250Fysisk institutt - Rikshospitalet (a)(b) Precision, (a) low, (b) high

FYS4250Fysisk institutt - Rikshospitalet Accuracy: (a) low, (b) high (a)(b)

FYS4250Fysisk institutt - Rikshospitalet Sensitivity Drifting

FYS4250Fysisk institutt - Rikshospitalet Linearity

FYS4250Fysisk 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), output y(t)

FYS4250Fysisk institutt - Rikshospitalet 0. order system, static, no energy storing

FYS4250Fysisk institutt - Rikshospitalet 1.order system, one energy storing element, relaxation

FYS4250Fysisk institutt - Rikshospitalet 2.order system, two energy storing elements, swinging system

FYS4250Fysisk institutt - Rikshospitalet 2.order system, blood pressure monitoring

FYS4250Fysisk institutt - Rikshospitalet Teknology: How to Design, construct Produce, market Medical equipment