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FYS 4250. Biomedical instrumentation. Chapt 1: Basic concepts of medical instrumentation. Medical instrumentation, intensive care unit. Operating room. Approaches. Physicians Physicists, engineers Researcher Patients Functions: diagnostic, therapeutic, support Invasive / non-invasive
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FYS 4250 Biomedical instrumentation Chapt 1: Basic concepts of medical instrumentation Fysisk institutt - Rikshospitalet
Medical instrumentation, intensive care unit Fysisk institutt - Rikshospitalet
Operating room Fysisk institutt - Rikshospitalet
Approaches • Physicians • Physicists, engineers • Researcher • Patients • Functions: diagnostic, therapeutic, support • Invasive / non-invasive • Technology: electromagnetic, optical, mecanical 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 Fysisk institutt - Rikshospitalet
Interfering modifying desired Fysisk institutt - Rikshospitalet
Example: modifying, interfering input Fysisk institutt - Rikshospitalet
Regulation systems of the body Fysisk institutt - Rikshospitalet
Servo loop Fysisk institutt - Rikshospitalet
Servo (negative feedback) Eq.1.3 y = output xd = desired input Gd = gain Hf = part of y back to input Fysisk institutt - Rikshospitalet
Biostatistics • Sensitivity high → high true positive • Specificity high → high true negative Fysisk institutt - Rikshospitalet
Linear system fits the equation y = mx + b. • Nonlinear system does not fit the straight line. (a) (b) Fysisk institutt - Rikshospitalet
The one-point calibration may miss nonlinearity. • The two-point calibration may also miss nonlinearity. (a) (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. Fysisk institutt - Rikshospitalet
Precision, (a) low, (b) high (a) (b) Fysisk institutt - Rikshospitalet
Accuracy: (a) low, (b) high (a) (b) Fysisk institutt - Rikshospitalet
Sensitivity Drifting Fysisk institutt - Rikshospitalet
Linearity 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: a2d2y/dt2 +a1dy/dt+ a0y(t) = b2d2x/dt2 +b1dx/dt + b0x(t) input x(t), output y(t) Fysisk institutt - Rikshospitalet
0. order system, static, no energy storing Fysisk institutt - Rikshospitalet
1.order system, one energy storing element, relaxation Fysisk institutt - Rikshospitalet
2.order system,two energy storing elements, swinging system Fysisk institutt - Rikshospitalet
2.order system, blood pressure monitoring Fysisk institutt - Rikshospitalet
Teknology: How to Design, construct Produce, market Medical equipment Fysisk institutt - Rikshospitalet