primary ray


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primary ray

In radiographic imaging, the x-ray beam that originates at the source of radiation. It is usually used to differentiate those rays from the additional scatter radiation that constitutes the majority of the beam used to create images.
See also: ray
References in periodicals archive ?
The cone has then to be rotated in order to align its axis to the primary ray [^.D], by means of the matrices [Eq.
Some observers had found that this scattered or "secondary" radiation did strange things--it seemed to have a directionality to it and, most extraordinarily, to have a different, longer wavelength than the primary rays. What could be going on?
Inflorescence terminal, umbellate, 5-19 cm long, 3-7 cm wide, with 6-10 primary involucral bracts, the lowermost 1-2 leaf-like and exceeding the inflorescence, the uppermost setaceous, lowest involucral bract 10-30 cm long, 1.5-2.6 times as long as the inflorescence; primary rays 5-15 ascending to curving with age, at least the thinnest more or less flexuous, flattened or compressed-trigonous, antrorsely scabrous on margins distally, smooth proximally, the longest 5-11 cm, second, third, and occasionally fourth order branching present, with the spikelets ultimately sessile or rarely short-peduncled (< 5 mm) in fascicles of 2-7 or rarely solitary at tips of primary or second order branches.