Radiographic unsharpness, or geometric unsharpness (Ug) as it is widely known in the NDT (Non-destructive Testing) industry, can be measured and controlled. Ug is related to the geometry of the radiographic technique and simply put, is the amount of 'blur' present in a radiological image. The primary factors contributing to Ug in the radiographic technique are: 1. A excessively large focal spot (point from which the usable radiation beam emanates). In X-ray tubes, this is the area where high speed electrons are focused onto the target, resulting in the generation of photons. In gamma-ray sources, focus is the actual physical size of the radioactive material. Typical focus for an industrial X-ray tube (10 mA) may range from 4 to 7 mm. Gamma-ray source size is often about 1/8". 2. Excessive test specimen (object) to detector distance, as related to focal spot size (FSS). There are mini- and micro-focus X-ray systems available that can be used to magnify the image of the test specimen (up to 100x or more), while limiting Ug. Some of these micro-focus X-ray systems may have a focus of less than 10 microns. Gamma-ray sources are manufactured to have as high of a specific activity (radiation output per unit of mass) as possible, thus limiting physical size of the source material and resultant exposure time. Ug can be minimized by using as small a focal spot as possible or available, keeping the test specimen in contact with or as close to the detector as possible, or using a longer source to film distance (which will increase exposure time). These factors can be adjusted to suit the inspection application, or to achieve compliance with a specification. Also, any motion of the test specimen, detector or source that may occur during exposure will cause unsharpness, but this situation is not related to geometry. Industrial radiography specifications limit acceptable Ug from .04" down to .002", depending upon material thickness and service application (aerospace component vs. automotive part) of the test specimen. Ug for any radiographic technique can be easily calculated using the following formula: Ug=FSS x ODD/SOD FSS=Focal spot size ODD=Object to detector distance(source side of object to detector distance) SOD=Source to object distance
Yes, Increased SID = decreased radiographic density. Decreased SID = Increased radiographic density
what is the principal of radiography
Uranium (fuel source) Iridium (radiographic source) Radium (flourescent source)
image magnification,image distortion,image un sharpness
An increase in a film/screen combination increases density. It is a directly proportional relationship.
geometric unsharpness is fixed by setting the focal radius,etc. while radiographic unsharpness consists of both geometric and film unsharpness.
Technetium is not "radiographic" but it is radioactive.
how to calculate radiographic sensitivity
radiographic involving the urinary system is called;
What is radiographic study of the arteries? It is an arteriogram, a graphic image or x-ray of the internal arteries.
What is radiographic study of the arteries? It is an arteriogram, a graphic image or x-ray of the internal arteries.
Yes, Increased SID = decreased radiographic density. Decreased SID = Increased radiographic density
cassette
The result of a radiographic examination.
Radiographic testing is similar to taking of an x-ray of a weld. It checks for integrity, penetration, and other necessary factors.
do you know about Penumbra calculation as its calculated from this? Ug=FxT/D Ug=Geometric Unsharpness F= Source or Window Size T= Object Thickness D= Distance from source to the front surface of the Test Object. Your Diagnostic film length is calculated from this. Depending on what standards you work to they will tell you how many shots to do on what thickness of material as well as distance shot from. there is a chart that can be referenced but i can't remember what its called. i will try & find out but i hope this helps
what is the principal of radiography