Imaging or therapy using administered radiopharmaceuticals. The distribution of the labelled compound selects biological function or tissue, while emitted radiation provides a measurement or deposited energy.
Treatment through controlled deposition of ionizing absorbed dose. External beams and internal radiopharmaceuticals require different delivery and radiation dosimetry models.
An effect-equivalent dose derived from the linear-quadratic radiobiology model, with a subscript often indicating the tissue's assumed in gray. It is distinct from the physical total absorbed dose . Increasing fraction size at fixed tumour BED can increase the normal-tissue BED when the latter has smaller .
A model for surviving fraction after radiation dose . Independent fully repaired fractions add their logarithmic effects. For equal fractions and no repopulation, dividing the total log kill by gives the biologically effective dose . Comparing tissue types requires their own parameters and the same stated repair assumptions.
The variation of absorbed dose with depth for a specified beam, geometry and medium. A megavoltage photon beam has a secondary-electron buildup region followed by gradual dose reduction. A nearly monoenergetic proton beam instead exhibits a Bragg peak near the end of its range.
A specified geometry, beam configuration and dose prescription intended to cover a target while limiting normal-tissue dose. Robustness to setup, motion and anatomy changes is part of assessing a plan.
Treatment using proton beams with controllable finite range and a Bragg peak. Potential normal-tissue sparing must be assessed against range uncertainty, motion and biological-effect uncertainties.
Uncertainty in where a charged-particle beam stops because of material conversion, anatomy, motion or delivery errors. A steep distal dose gradient makes it particularly consequential for target coverage and nearby tissue.
External-beam treatment using photons that create secondary charged particles in tissue. Megavoltage depth-dose curves usually show build-up followed by an extended fall-off and exit dose.
Treatment using spatially varying beam fluence to shape the combined three-dimensional dose distribution. Improved target conformity may come with dose distributed through a larger volume at lower levels.
Functional imaging of bone-seeking tracer uptake with a gamma camera or single-photon emission computed tomography. Uptake patterns can reveal abnormal bone turnover.
A position-sensitive detector, usually using a collimator, scintillator and light sensors, that forms a projection image of a gamma-emitting tracer. Energy selection reduces scattered-photon contamination.
A pharmaceutical containing a radionuclide, with uptake and clearance chosen for imaging or treatment. Biological targeting and radioactive decay jointly determine its useful signal and tissue dose.
An iodine radionuclide with approximately eight-day half-life, emitting beta particles and gamma rays. Its uptake and retention depend strongly on the carrier and tissue physiology.
Radioiodide used in selected thyroid treatments because iodine uptake localizes activity in thyroid tissue. Iodine-131 supplies local beta radiation and imageable gamma emission.
A diagnostic bone tracer combining technetium-99m with a diphosphonate carrier. Uptake reflects bone turnover and delivery, rather than a unique disease diagnosis.
A metastable nuclear isomer used in diagnostic tracers, with approximately six-hour half-life and imageable gamma rays. Its chemical carrier determines biological uptake.
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Nuclear medicine is a specialized field of medical imaging and therapy that utilizes radioactive materials, or radiopharmaceuticals, for diagnosis and treatment of various health conditions. It involves the use of small amounts of radioactive substances to carry out imaging and therapeutic procedures. ### Diagnostic Uses In diagnostic applications, nuclear medicine techniques can visualize the function of organs and tissues.