Specimen radiography

Available data is still inadequate for an accurate appraisal of the future clinical role of DBT. However, one may speculate about the possible benefit of this new technique for a range of different applications based on theoretical considerations. DBT has the potential to improve specimen radiography. Two-dimensional mammography will never allow absolutely accurate evaluation of the site of an abnormality in a surgical specimen. Specimen radiography in two planes provides much more accurate information nevertheless, it may also fail to demonstrate contiguity of a focal lesion with the resection margin. The... 

Fig. 4.13. a Specimen radiography of cores obtained with the 8-gauge directional vacuum-assisted biopsy probe demonstrated multiple calcifications. Cores have been placed together in a plastic cassette, b Optionally, core biopsy specimens may be separated on a filter paper to identify those that contain calcifications before they are submitted to pathology... 

Fig. 4.18a, b. Asymptomatic woman with bifocal infracenti-metric clusters of calcifications (arrows) requiring excision, a Mammogram confirms adequate location of two localizing wires, b Specimen radiography... 

The assignment of a lesion into one of these types is purely morphological and based on the anatomical location of the tumor or the best estimate of its epicenter for those with advanced disease. Classification can be performed easily based on a combination of contrast radiography, upper endoscopy, and CT (38). In a retrospective analysis of 74 patients with gastric cancer, the preoperative classification had a high correlation (95%) to the final classification based on the resected specimen (39). 

A total of 29 additional cylindrical silicon nitride tensile specimens have been received for inspection with the CT system. Initial inspection will be done utilizing digital radiography. Any sample showing any type of discontinuity will be further evaluated with one or more CT slices through the longitudinal center of the sample. 

Static neutron radiography produces an image on film that has been exposed to the secondary radiation produced when neutrons from the reactor penetrate the specimen and interact with a neutron absorbing screen. 

Low power level research reactors with a beam port are well suited for static neutron radiography. The thermal neutron beam intensity at the specimen position should be greater than 10... 

Fast neutrons cause a loss of contrast in the film image due to specimen and shielding scattering. The use of a radial beam port requires filters and a collimator to produce a highly thermalized beam. Therefore, the use of a tangential beam port is preferable. At some reactors, the radiography facility neutrons are provided by a cold neutron source. 

Measurement sensitivity divides the metal loss methods. Ultrasonics and radiography are usually considered as inspection methods. Typically, ultrasonics has a measurement resolution of around 50 pm (0.002 in.), and radiography 250 p,m (0.010 in.). Consequently, these types of measurements are typically made annually. Corrosion test specimens (coupons) assess metal loss typically over a one to three month interval. Electrical resistance probes, as an automatic coupon, assess metal loss typically over a few hours to a few weeks. 

In practice, this is measured with a microscope at a sufficient magnification. First, the specimens are pickled in order to eliminate any corrosion products. Then the image is focussed first on the uncorroded surface at the pit s rim, and then on the bottom of the pit This measurement can also be taken by radiography of the samples, followed by image analysis [10]. 

Radiography (x-ray/ gamma ray) Subsurface >2% of specimen thickness Laboratory/in-field... 

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