focal spot


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Related to focal spot: fovea

spot

 [spot]
a circumscribed area or place, usually distinguished by its color; see also macula and tache.
actual focal spot the section of a focal spot on which there is intersection of an electron beam with an anode of an x-ray tube.
Bitot's s's foamy gray triangular spots of keratinized epithelium on the conjunctivae, a sign of vitamin A deficiency.
blind spot
café au lait spot a light brown pigmented macule seen in neurofibromatosis and albright's syndrome.
cherry-red spot the choroid appearing as a red circular area surrounded by gray-white retina, as viewed throught the fovea centralis in tay-sachs disease. Called also Tay's spot.
cotton-wool spot white or gray soft-edged opacities in the retina composed of cytoid bodies; seen in hypertensive retinopathy, lupus erythematosus, and numerous other conditions.
effective focal spot the size of a projected focal spot in a specified direction measured with a quality assurance test tool such as the slit camera.
focal spot
1. the object of a patient's gaze during distraction techniques.
2. a small area of an x-ray target that receives the main electron stream.
Forschheimer s's a fleeting skin eruption consisting of discrete rose spots on the soft palate sometimes seen in rubella just prior to the onset of the skin rash.
Koplik's s's small, irregular, bright red spots on the buccal and lingual mucosa, with a minute bluish white speck in the center of each; they are pathognomonic of beginning measles.
liver spot
1. a lay term for senile lentigo.
2. (in pl.) tinea versicolor.
mental blind spot mental scotoma.
mongolian spot a type of congenital brown to gray-blue nevus; see also mongolian spot.
Roth's s's round or oval white spots consisting of coagulated fibrin seen in the retina in a number of diseases in which a vascular insult resulting in hemorrhage is followed by healing.
Tay's spot cherry-red spot.

fo·cal spot

the site of bombardment by electrons and emission of x-rays from the anode of an x-ray tube.
See also: focal spot size.

focal spot

the area on the anode of an x-ray tube or the target of an accelerator that is struck by electrons and from which the resulting x-rays are emitted. The shape and size of a focal spot influence the resolution of a radiographic image. An increase in focal spot size, which may accompany deterioration of the x-ray tube, reduces the ability to define small structures. Also called actual focal spot.

fo·cal spot

(fō'kăl spot)
The area made of tungsten on the anode of a diagnostic x-ray tube. The electrons interact with it to produce x-rays.

fo·cal spot

(fō'kăl spot)
The area made of tungsten on the anode of a diagnostic x-ray tube. The electrons interact with it to produce x-rays.

focal spot,

focal spot

the area on the target of the x-ray tube which the electron stream strikes and from which x-rays are emitted. Called also focus. The larger the area of the focal spot, the poorer is the detail in the x-ray image.

actual focal spot
the actual area of the focal spot on the radiographic target as viewed at right angles to the plane of the target.
broad focal spot
a relative term which refers to the effective dimension of the x-ray focal spot usually greater than 1 mm2. See also fine focal spot (below).
effective focal spot
the face of the anode that carries the target in an x-ray tube is slanted from the vertical to increase the volume of the target but to reduce the size of the origin of the x-ray beam.
focal spot-film distance
see focal-film distance.
fine focal spot
a focal spot of less than 1 mm2 which is used in radiography studies where high detail is required.
focal spot-skin distance
distance from the film spot to the skin of a patient receiving radiation therapy.
References in periodicals archive ?
With the increasing of the focal spot value to 20mm (sample P3) there is an increase in penetration of the remelted zone and an extension of the dilution effect.
NeuViz 16 multi-slice CT scanner is designed with the latest integrated detector for optimized SNR and scanning time, and its patented technology of dynamic focal spot ensures a higher spatial resolution during scanning and creates more detailed 3D/MPR images.
Additionally, a unique triple-focus design provides small focal spot redundancy for fail-safe cardiac imaging.
The exceptional beam quality and stability will enable to use focusing techniques to prepare submicron beam sizes at the sample position with focal spot sizes down to 50 nm.
These include the phoenix|sentry, the first fully automated ball grid array (BGA) inspection system with wetting analysis and the Nanofocus analyser series, the only system available on the market capable of achieving a focal spot of less than one micron.
Additionally, a unique triple-focus design provides small focal spot redundancy for fail-safe cardiac imaging, while the acoustically quiet operating design permits clear communication in the examination room among the physician, staff and patient.
Both DIAMOND and PERFORMA have the new Diamond x-ray tube, with precision machined cathode constructions, which gives a Gaussian intensity distribution within the focal spot for highest possible resolution.
Unlike the first generation CCD based systems that compromise the image quality the OP 100 D takes advantage of small focal spot and inherent stability of Instrumentarium's OP 100 system in order to produce image quality that exceeds that of conventional film images of most panoramic units.
It also can accommodate up to 100mm targets for improved focal spot track loading and shorter exposure times without requiring an increase in overall tube dimensions.
Each focal spot produces an image at a rate of 15 images per second.

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