Assuntos
Meios de Contraste/história , Radiografia/história , Angiografia/história , Sulfato de Bário/história , Bismuto/história , Colecistografia/história , Meios de Contraste/efeitos adversos , Trato Gastrointestinal/diagnóstico por imagem , História do Século XIX , História do Século XX , Humanos , Iodetos/história , Óleo Iodado/história , Fenolftaleínas/história , Radiografia/métodos , Dióxido de Tório/história , Urografia/históriaRESUMO
PURPOSE: The generation of x-rays for diagnostic imaging, formation of the radiographic image, and pharmacodynamics of radiopaque drugs are reviewed. SUMMARY: Medical radiographic imaging uses x-rays to obtain an image of a particular structure or function of the human body. Darkening of the radiographic image occurs at points that correspond with the interactions of x-rays. Unlike visible light, x-rays comprise a higher-energy, ionizing portion of the electromagnetic spectrum that is capable of penetrating and ionizing matter, breaking chemical bonds, damaging tissues, and rendering an image of tissue characteristics beneath the surface. The beam of x-rays is directed to a tissue target and emerges encoded with data that initiate image formation with film or a video screen (the receptor complex). Braking radiation and characteristic radiation form the primary beam, which is modified into the image-forming beam through interaction with the target. Radiopaque drugs selectively enhance the emergent data pattern and thereby improve formation of the image. Atomic electron theory is reviewed, and the interaction of x-rays with tissue and radiopaque drugs is discussed in detail. CONCLUSION: Radiopaque drugs can interact with x-rays to improve the visualization of tissues and anatomical structures.
