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Rachel Levine
Rachel Levine, American pediatrician and public health official; Pennsylvania physician general (2015) and health secretary (2017), then HHS assistant secretary for health (2021), first openly transgender federal official confirmed by the Senate and first female four-star admiral of the USPHS Commissioned Corps.
Rachel Robinson
Rachel Annetta Isum Robinson (born July 19, 1922) is an American nurse, psychiatric nursing educator, and civil rights activist; wife of Jackie Robinson, MCCR vice chairman, and founder of the Jackie Robinson Foundation.
Racing thoughts
Racing thoughts (tachyphrenia) is a symptom of abnormally fast, uncontrollable thinking, first named in DSM-III 1980 mania criteria; also seen in depression, ADHD, anxiety, and insomnia.
Racotumomab
Racotumomab, also known as 1E10 and marketed as Vaxira, is an anti-idiotype monoclonal antibody cancer vaccine approved in Cuba and Argentina for non-small cell lung cancer.
RACS study
RACS study (Risk in Acute Coronary Syndrome; Risk Markers in the Acute Coronary Syndromes, NCT00521976): single-center prospective Norwegian cohort of 871 chest-pain patients at Stavanger University Hospital, 2002-2003, studying risk markers, 24-month mortality, and recurrent troponin-T events.
Radboud University Medical Center
Radboudumc (Radboud University Medical Center, formerly Sint Radboud Ziekenhuis and UMC St Radboud) is the university medical center of Nijmegen, Netherlands; founded 1956, legally separate from Radboud University since 2021, with 11 care centers, 41 departments, and about 12,700 employees.
Rademikibart
Rademikibart (CBP-201, SIM0718) is a fully human IgG4 monoclonal antibody targeting IL-4Rα, developed by Connect Biopharma and licensed to Simcere for Greater China; NDA accepted by China's NMPA in July 2025 for atopic dermatitis, with phase 2 evidence in asthma.
Radial artery
The radial artery runs from the elbow down the thumb side of the forearm to the hand, and is the standard site for feeling a pulse.
Radial extracorporeal shock wave therapy
Radial extracorporeal shock wave therapy (rESWT), also called EPAT, is a noninvasive therapy that delivers low-energy pressure waves from a pneumatic applicator to treat tendinopathies such as plantar fasciitis.
Radial glial cell
Radial glial cell (RGC), embryonic neural stem cell spanning ventricle to pia; primary progenitor generating cortical neurons and glia and scaffold for neuronal migration; transforms into astrocytes after neurogenesis.
Radial keratotomy
Radial keratotomy (RK), a corneal incisional refractive surgery popularized by Svyatoslav Fyodorov, corrects myopia by radial corneal cuts that flatten the central cornea; known for progressive hyperopic shift and complicated post-RK cataract IOL calculation.
Radial nerve
Radial nerve: C5–T1 terminal branch of the brachial plexus posterior cord, supplying arm and forearm extensors and dorsal hand sensation; injuries cause wrist drop, Saturday night palsy, and Wartenberg's syndrome.
Radial probe endobronchial ultrasound
Radial probe endobronchial ultrasound, also known as radial EBUS, is a bronchoscopic ultrasound technique using a 20 MHz probe to localize peripheral lung lesions before biopsy.
Radiation boost
A radiation boost is an extra dose of radiotherapy delivered to the tumor bed after or during primary radiotherapy, most commonly after breast-conserving surgery for early breast cancer.
Radiation Dose Fractionation
Radiation dose fractionation, also called hypofractionation when larger, fewer fractions are used, divides a total radiotherapy dose into sessions; randomized trials in breast, prostate, and rectal cancer show similar survival to conventional 2 Gy daily schedules with fewer visits.
Radiation Dose Hypofractionation
Radiation dose hypofractionation delivers radiotherapy in fewer, larger fractions than the conventional 1.8-2.0 Gy: moderate (2.4-3.4 Gy) and ultrahypofractionation (≥5 Gy), established mainly in prostate cancer.
Radiation duodenitis
Radiation duodenitis, radiation-induced duodenal inflammation, is a complication of abdominal radiotherapy, especially pancreatic SBRT; fixed retroperitoneal position raises dose, causing ulcers, bleeding, stenosis, guided by dose-volume constraints.
Radiation Equipment and Supplies
Radiation Equipment and Supplies (MeSH D055618, E07.710): instruments, apparatus, components, and expendables for radiation applications, from linacs and cobalt-60 units to brachytherapy afterloaders, dosimeters, and treatment planning systems, with their QA, safety, and regulation.
Radiation gastritis
Radiation gastritis is inflammation of the stomach lining caused by ionizing radiation, usually during radiotherapy for stomach, esophageal, or pancreatic tumors, ranging from mild nausea to severe ulcers and bleeding.
Radiation myelitis
Radiation myelitis, or radiation-induced myelopathy, is spinal cord injury from radiotherapy, spanning transient Lhermitte's-sign myelopathy and chronic progressive myelitis; risk is dose- and fractionation-dependent, rising sharply above 50 Gy.
Radiation oesophagitis
Radiation oesophagitis (radiation-induced esophagitis, RE, ICD-11 DA24.22) is radiation-caused inflammation of the esophageal mucosa after thoracic radiotherapy, causing dysphagia and odynophagia 2-3 weeks in, usually self-limited.
Radiation oncology
Radiation oncology is the medical specialty that treats cancer with high-energy radiation, damaging cancer cells' DNA through external beams, brachytherapy, or radioactive isotopes given throughout the body.
Radiation proctitis
Radiation proctitis, also called radiation proctopathy, is rectal mucosal injury from pelvic radiation therapy for prostate, rectal, cervical, or anal cancer; about 75% develop the acute form and roughly 1-20% the chronic bleeding form.
Radiation retinopathy
Radiation retinopathy, also called radiation-induced retinopathy, is a progressive occlusive retinal vasculopathy after ocular or periocular radiotherapy, most often plaque brachytherapy for uveal melanoma, causing ischemia, macular edema, and vision loss.
Radiation segmentectomy
Radiation segmentectomy is a liver-directed radioembolization technique that delivers ablative yttrium-90 microsphere doses to one or two hepatic segments, most often to treat solitary hepatocellular carcinoma.
Radiation therapy
Radiation therapy (radiotherapy, irradiation): cancer treatment using high-energy x-rays, gamma rays, protons, or radioactive sources to damage tumor DNA. Delivered as external beam, brachytherapy, or systemic therapy; main risk is normal-tissue toxicity.
Radiation-induced brain injury
Radiation-induced brain injury (ICD-11 8E61.0), also called post-radiation brain injury or cerebral radionecrosis, is brain damage from therapeutic cranial irradiation, divided into acute, early-delayed, and late-delayed syndromes, causing cognitive impairment and necrosis in long-term survivors.
Radiation-induced colitis
Radiation-induced colitis (放射線誘発性大腸炎, ICD-11 DB33.41) is radiation-therapy-caused colonic mucosal inflammation, acute within 60 days or chronic after months to years, dose-dependent above roughly 45–70 Gy.
Radiation-induced Moyamoya syndrome
Radiation-induced moyamoya syndrome (RIMS): moyamoya vasculopathy after cranial radiotherapy, mainly in children irradiated for optic pathway glioma or craniopharyngioma; median latency about 40 months, dose- and NF-1-dependent risk, treated by revascularization.
Radiation-induced plexopathy
Radiation-induced plexopathy (RIBP, RILSP) is rare progressive damage to the brachial or lumbosacral nerve plexus after cancer radiotherapy, appearing months to decades later; typically painless, often bilateral, with fibrosis and no proven disease-modifying treatment.