Biophysics & Medical Physics
60 terms · page 3 of 3
Pulse Oximetry
Biophysics & Medical Physics
Percentage (% SpO₂)
A non-invasive medical monitoring method measuring arterial blood oxygen saturation (SpO₂) using differential optical absorption of red and infrared light.
Ratio R = (AC₆₆₀/DC₆₆₀) / (AC₉₄₀/DC₉₄₀) ⇒ % SpO₂
Radiation Dosimetry
Biophysics & Medical Physics
Gy (Gray = J/kg)
The subfield of medical physics quantifying and measuring ionizing radiation energy deposited in human tissues or phantom materials.
D = dĒ / dm (Absorbed Energy per Unit Mass)
Radiobiology
Biophysics & Medical Physics
Gy (Dose Response Units)
The study of the biological mechanisms and health effects of ionizing radiation acting on living cells and biological tissues.
DNA Double-Strand Breaks (DSB) ~ 35–40 per Gy per Cell
Radiopharmaceuticals
Biophysics & Medical Physics
MBq or mCi (Administered Activity)
Pharmaceutical compounds containing radioactive isotopes administered to patients for target-specific diagnostic imaging or therapy.
Targeted Radionuclide Compound: Radiotracer + Carrier Molecule
Radiotherapy
Biophysics & Medical Physics
Gy (Gray = J/kg) Total Prescribed Dose
The clinical treatment of malignant cancer tumors using precisely targeted ionizing radiation beams to induce double-strand DNA damage in cancer cells.
Linear-Quadratic Cell Survival: S = exp(-α D - β D²)
Relative Biological Effectiveness (RBE)
Biophysics & Medical Physics
Dimensionless Ratio
The ratio of absorbed dose of a reference 250 kVp X-ray beam to the absorbed dose of a test radiation type required to produce an identical biological effect.
RBE = D_reference (250 kVp X-rays) / D_test (for equal biological effect)
SPECT Scan
Biophysics & Medical Physics
MBq (Activity) & Hounsfield-like Functional Units
Single-Photon Emission Computed Tomography (SPECT), a nuclear medicine 3D functional imaging technique using gamma-emitting radioisotopes.
Gamma Camera 3D Tomographic Reconstruction
Stochastic vs Deterministic Radiation Effects
Biophysics & Medical Physics
Risk Factor / Dose Threshold (Gy)
The classification of biological radiation damage into probability-driven stochastic risks (cancer) and threshold-driven deterministic tissue reactions (cataracts, erythema).
Stochastic Probability P ∝ Dose; Deterministic Severity ∝ Dose (Threshold D_th)
Tissue Viscoelasticity
Biophysics & Medical Physics
Pa (Modulus) & Pa·s (Viscosity η)
The mechanical property of biological tissues exhibiting both elastic solid-like storage and viscous fluid-like energy dissipation under deformation.
Maxwell / Kelvin-Voigt Models: σ(t) = E ε(t) + η (dε / dt)
Weber-Fechner Law
Biophysics & Medical Physics
Psychophysical Scale (e.g. dB, Stellar Magnitude)
A psychophysical law stating that human subjective sensory perception is proportional to the logarithm of the physical stimulus intensity.
p = k ln(S / S₀) (Perceived Sensation = k ln(Stimulus Intensity))
X-Ray Crystallography in Biology
Biophysics & Medical Physics
Å or nm (Structural Resolution)
An experimental biophysical technique determining the 3D atomic structure of biological macromolecules from X-ray diffraction patterns of crystallized proteins or nucleic acids.
n λ = 2 d sin θ (Bragg's Law for Macromolecules)
X-ray Imaging
Biophysics & Medical Physics
keV (Photon Energy) & μ (Attenuation Coefficient in cm⁻¹)
A diagnostic medical imaging modality using differential photoelectric attenuation of X-rays passing through human tissue to form 2D projection shadowgraphs.
I(x) = I₀ e^(-μ x) (Beer-Lambert Attenuation)