Photofluorography (sometimes called just fluorography) is
photography
Photography is the visual arts, art, application, and practice of creating images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is empl ...
of
X-ray
An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...
images from a
fluorescent
Fluorescence is one of two kinds of photoluminescence, the emission of light by a substance that has absorbed light or other electromagnetic radiation. When exposed to ultraviolet radiation, many substances will glow (fluoresce) with color ...
screen.
[Photofluorography](_blank)
/ref> It is commonly used in some countries for chest X-ray screening, e.g. to diagnose tuberculosis
Tuberculosis (TB), also known colloquially as the "white death", or historically as consumption, is a contagious disease usually caused by ''Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can al ...
(see Abreugraphy for more information on such usage of this technique).
Method of image formation in photofluorography
X-ray beams from the tube get attenuated by the patient producing a transmitted radiation intensity
In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. This includes:
* ''electromagnetic radiation'' consisting of photons, such as radio waves, microwaves, infr ...
corresponding to the part of the body traversed by the X-ray beam. Transmitted intensities now fall on the photocathode
A photocathode is a surface engineered to convert light (photons) into electrons using the photoelectric effect. Photocathodes are important in accelerator physics where they are utilised in a photoinjector to generate high brightness electron ...
stimulating it to produce electron
The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...
s in quantities external to the light intensities emitted by the input. This is caused by the formation of a light image of the transmitted radiation pattern
In the field of antenna design the term radiation pattern (or antenna pattern or far-field pattern) refers to the ''directional'' (angular) dependence of the strength of the radio waves from the antenna or other source.Constantine A. Balanis: " ...
. Electrons from the photocathode are accelerated and focused electronically out on the output phosphor
A phosphor is a substance that exhibits the phenomenon of luminescence; it emits light when exposed to some type of radiant energy. The term is used both for fluorescent or phosphorescent substances which glow on exposure to ultraviolet or ...
which emits light as a result of electron bombardment
Electron ionization (EI, formerly known as electron impact ionization and electron bombardment ionization) is an ionization method in which energetic electrons interact with solid or gas phase atoms or molecules to produce ions. EI was one of th ...
. This shows a magnified image of what appears on the input phosphor. The semitransparent mirror splits the image in which one part is focused by the camera lens
A camera lens, photographic lens or photographic objective is an optical lens (optics), lens or assembly of lenses (compound lens) used in conjunction with a camera body and mechanism to Imaging, make images of objects either on photographic film ...
onto the film
A film, also known as a movie or motion picture, is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, emotions, or atmosphere through the use of moving images that are generally, sinc ...
to form the image. The image size depends on the focal length
The focal length of an Optics, optical system is a measure of how strongly the system converges or diverges light; it is the Multiplicative inverse, inverse of the system's optical power. A positive focal length indicates that a system Converge ...
of the camera lens.
At the same time, the TV camera
A professional video camera (often called a television camera even though its use has spread beyond television) is a high-end device for creating electronic moving images (as opposed to a movie camera, that earlier recorded the images on filmstoc ...
lens focuses the light to form an image on the TV camera photoreceptor where the image is transformed to a complex electronic signal and sent to the electronic image distributor. This then passes the image to the various display or recording devices, e.g. a videotape recorder
A video tape recorder (VTR) is a tape recorder designed to record and playback video and audio material from magnetic tape. The early VTRs were open-reel devices that record on individual reels of 2-inch-wide (5.08 cm) tape. They were u ...
, kinescope
Kinescope , shortened to kine , also known as telerecording in Britain, is a recording of a television program on motion picture film directly through a lens focused on the screen of a video monitor. The process was pioneered during the 1940s ...
, TV, or display.
See also
* Chest photofluorography
References
{{Medical imaging
Fluoroscopy