All articles starting with R
22,461 articles
Radiolites
Radiolites is an extinct genus of rudist bivalves, marine mollusks with cone-shaped, reef-dwelling shells, established by Lamarck in 1801; its fossils occur in Cretaceous shallow-water carbonates from the early Aptian to the Maastrichtian.
Radiologic technology
Radiologic technology: allied health profession of radiologic technologists (radiographers) performing X-ray, CT, MRI, nuclear medicine, and ultrasound imaging and radiation therapy; rooted in Roentgen's 1895 X-ray discovery, credentialed by ARRT, organized by ASRT.
Radiological Society of North America
Radiological Society of North America (RSNA), founded 1915 as the Western Roentgen Society, is a non-profit radiology society in over 160 countries, publisher of Radiology and five other journals and host of the annual Chicago meeting.
Radiologists
Radiologists: physicians who diagnose and treat disease using medical imaging (X-ray, CT, MRI, PET, ultrasound). Diagnostic and interventional branches; 13+ years training; major workforce shortages in the US and UK.
Radiology
Radiology: medical specialty using imaging (X-ray, CT, MRI, ultrasound, nuclear medicine) to diagnose disease and guide treatment; includes diagnostic and interventional branches, distinct from radiography, a single X-ray imaging modality.
Radiology Partners
Radiology Partners is the largest physician-owned radiology practice in the United States, co-founded in 2012 by Rich Whitney and Dr. Anthony Gabriel and based in El Segundo, California.
Radioluminescence
Radioluminescence, also known as radiofluorescence or scintillation, is the light emitted when ionizing radiation excites a material; it underlies radiation detection, tritium exit signs, and radiotherapy dosimetry.
Radiolysis
Radiolysis is the use of ionizing radiation, such as gamma rays, X-rays, or electron beams, to break chemical bonds and decompose or synthesize molecules in gases, liquids, or solids.
Radiometric calibration
Radiometric calibration is the process of relating a radiation sensor's output, such as image pixel values, to physical light quantities like radiance or irradiance, traceable to the SI.
Radiometric dating
Radiometric dating, also called radioactive dating, is a family of techniques that determine the age of rocks and materials by measuring radioactive isotopes and their decay products at known rates.
Radiomics
Radiomics is a method in medical imaging, defined in 2012, that extracts hundreds of quantitative features from radiographic images to build statistical models for diagnosis and prognosis.
RadioML dataset
The RadioML dataset is a family of public radio signal datasets from DeepSig Inc., released from 2016, with labeled I/Q samples for training automatic modulation classification systems.
Radion
The radion is a hypothetical scalar particle appearing in theories with compactified extra dimensions, whose value measures the size of, or separation between branes in, the extra dimension.
Radionuclide
A radionuclide, also known as a radioisotope or radioactive isotope, is an unstable atom that spontaneously decays, emitting radiation such as alpha and beta particles until it becomes stable.
Radionuclide Generators
A radionuclide generator, colloquially a "radioisotope cow," is a device holding a long-lived parent isotope whose short-lived daughter is repeatedly "milked" off for nuclear medicine imaging.
Radionuclide therapy
Radionuclide therapy, also called molecular radiotherapy or radioligand therapy, treats cancer by injecting radioactive substances that accumulate in or bind to tumor cells, a method used since the 1940s.
Radionuclide ventriculography
Radionuclide ventriculography (RNV, MUGA, gated blood pool scan, ERNA) is a nuclear medicine test measuring ventricular ejection fraction with Tc-99m labeled red cells and ECG-gated gamma camera imaging, by first-pass or equilibrium methods; once the main nuclear cardiology technique, now used when echo or MRI are unsuitable.
Radiopharmace (辐联医药)
Radiopharmace, also known as Full-Life Technologies (辐联医药), is a clinical-stage radiopharmaceutical company founded in 2021 in Shanghai, developing actinium-225 radioligand therapies for cancer, including prostate cancer, with nearly $350 million raised.
Radiopharmaceutical therapy
Radiopharmaceutical therapy, also called radioligand therapy or targeted radionuclide therapy, is a cancer treatment in which an injected radioactive drug delivers radiation selectively to tumor cells, guided by imaging.
RadioShack
RadioShack is an American consumer-electronics retail chain founded in Boston in 1921, which collapsed through bankruptcies in 2015 and 2017 and survives as a brand.
Radiosity (computer graphics)
Radiosity is a global illumination method in computer graphics that computes light exchange between diffusely reflecting surfaces, introduced at SIGGRAPH 1984 by Cornell University researchers.
Radiosonde
A radiosonde, also called a rawinsonde or balloon sonde, is a balloon-borne instrument measuring pressure, temperature, and humidity up to 35 km, invented in 1929 and launched twice daily worldwide.
Radiostereometric analysis
Radiostereometric analysis (RSA) is a radiographic technique measuring three-dimensional micromotion of joint implants and bone segments in living patients, using paired simultaneous X-ray exposures and implanted tantalum markers.
Radiosurgery
Radiosurgery, also known as stereotactic radiosurgery (SRS), is a non-surgical radiation therapy that delivers precisely targeted, high radiation doses, most often to brain targets, with about 1 mm accuracy.
Radiosynthesis
Radiosynthesis is the chemical synthesis of radiolabeled compounds, incorporating positron-emitting isotopes such as carbon-11 and fluorine-18 into biologically active molecules, most often radiotracers for PET imaging.
Radiotelephone
Radiotelephone is telecommunication by radio waves carrying voice or other audio, covering ship-to-shore radio, air traffic control, and early wireless telephony; it contrasts with coded radiotelegraphy.
Radioteletype
Radioteletype (RTTY), or radio teletypewriter, is a method of sending printed text by radio, using frequency-shift keying to drive a teleprinter; amateurs adopted it in the 1950s.
Radiotherapy
Radiotherapy is a cancer treatment that uses ionizing radiation to kill tumor cells while sparing healthy tissue, given to about half of all cancer patients.
Radiotherapy Dosage
Radiotherapy dosage: specification and delivery of absorbed radiation dose in gray, divided into fractions (standard 1.8-2 Gy daily); governed by fractionation principles from Regaud and Coutard, ICRU-83/91 dose-volume reporting, and dose-escalation trials.
Radiotherapy Setup Errors
Radiotherapy setup errors are misalignments between the patient's treatment position and the planning image position. Also called positioning or geometric miss errors; detected by portal imaging, CBCT, or surface-guided radiotherapy; minimized with daily IGRT.