(a) Source-Side IQI(s). When using separate blocks for IQI placement as described inT-277.1(a), the thickness of the blocks shall be such that the image brightness at the body of the IQI is judged to be equal to or greater than the image brightness at the area of interest for a negative image format. If verified by measurement, pixel intensity variations up to 2% are permitted in the determination of
“equal to.”This image brightness requirement is reversed for a positive image format.
(b)All other requirements ofT-277.1shall apply.
VIII-277.2 Number of IQIs.
(a) Multiple IQIs. An IQI shall be used for each applic- able thickness range inTable T-276spanned by the minimum-to-maximum thickness of the area of interest to be radiographed.
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(b)As an alternative to(a)above, a minimum of two IQIs representing the minimum and maximum thick- nesses of the area of interest may be used, provided the requirements ofVIII-288are met.
(c)All other requirements ofT-277.2shall apply.
(d)Comparators such as digitized film strips, gray scale cards, etc., may be used to aid in judging displayed image brightness. When comparators are used to judge areas within the image, they need not be calibrated. Pixel inten- sity values may also be used to quantify image brightness comparisons.
VIII-277.3 Shims Under Hole IQIs.For welds with re- inforcement or backing material, a shim of material radio- graphically similar to the weld metal and/or backing material shall be placed between the part and the IQIs, such that the image brightness at the body of the IQI is judged to be equal to or greater than the image brightness at the area of interest for a negative image format. If ver- ified by measurement, pixel intensity variations up to 2%
are permitted in the determination of“equal to.”This im- age brightness requirement is reversed for a positive im- age format.
The shim dimensions shall exceed the IQI dimensions such that the outline of at least three sides of the IQI shall be visible in the radiograph.
VIII-280 EVALUATION
VIII-281 SYSTEM-INDUCED ARTIFACTS
The digital image shall be free of system-induced arti- facts in the area of interest that could mask or be con- fused with the image of any discontinuity.
VIII-282 IMAGE BRIGHTNESS
The image brightness through the body of the hole-type IQI or adjacent to the designated wire of the wire-type IQI, shall be judged to be equal to or greater than the image brightness in the area of interest for a negative image for- mat. If verified by measurement, pixel intensity variations up to 2% are permitted in the determination of“equal to.” This image brightness requirement is reversed for a posi- tive image format. Additionally, the requirements of T-282are not applicable to phosphor imaging plate radiography.
VIII-283 IQI SENSITIVITY
VIII-283.1 Required Sensitivity.Radiography shall be performed with a technique of sufficient sensitivity to display the designated hole-type IQI image and the es- sential hole, or the essential wire of a wire-type IQI. The radiographs shall also display the IQI identifying numbers and letters. Multiple film technique is not applicable to phosphor imaging plate radiography.
VIII-284 EXCESSIVE BACKSCATTER
For a negative image format, the requirements ofT-284 shall apply. For a positive image format, if a dark image of the“B,”as described inT-223, appears on a lighter back- ground of the image, protection from backscatter is insuf- ficient and the radiographic image shall be considered unacceptable. A light image of the“B”on a darker back- ground is not cause for rejection.
VIII-287 DIMENSIONAL MEASURING
VIII-287.1 Measuring Scale Comparator.The mea- suring scale used for interpretation shall be capable of providing dimensions of the projected image. The mea- surement scale tool shall be based on one of the following:
(a)a known dimensional comparator that is placed on the cassette prior to exposure
(b)a known dimensional comparator that is inscribed on the imaging plate prior to processing
(c)a known comparator scale placed on the imaging plate prior to processing
VIII-287.2 Alternative Comparator.As an alternative to a measuring scale comparator, a dimensional calibra- tion of the measuring function based upon a verifiable scanned pixel size may be used.
VIII-288 INTERPRETATION
Final radiographic interpretation of the area of interest shall be performed within the identified IQI image con- trast and brightness values or, if multiple IQIs are used, the overlapping portions of the identified contrast and brightness values for the intervening thickness ranges.
The IQI and the area of interest shall be of the same image format (positive or negative). Additionally, where applicable
(a)the contrast and brightness range that demon- strates the required IQI sensitivity shall be used for inter- pretation. When more than one IQI is used to qualify multiple thicknesses, the overlapping portions of each IQI’s determined contrast and brightness range shall be considered valid for interpretation of intervening thick- nesses. Pixel intensity values may also be used to quantify image brightness comparisons in accordance with VIII-277.1,VIII-277.3, andVIII-282.
(b)the digital image may be viewed and evaluated in a negative or positive image format.
(c)independent areas of interest of the same image may be displayed and evaluated in differing image for- mats, provided the IQI and the area of interest are viewed and evaluated in the same image format.
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VIII-290 DOCUMENTATION
VIII-291 DIGITAL IMAGING TECHNIQUE DOCUMENTATION DETAILS
The organization shall prepare and document the radiographic technique details. As a minimum, the follow- ing information shall be provided:
(a)the requirements ofArticle 1,T-190(a) (b)identification as required byT-224
(c)the dimensional map (if used) of marker placement in accordance withT-275.3
(d)number of exposures
(e)X-ray voltage or isotope used (f) source size (FinT-274.1)
(g)base material type and thickness, weld reinforce- ment thickness, as applicable
(h)source-to-object distance (DinT-274.1)
(i) distance from source side of object to storage phos- phor media (dinT-274.1)
(j) storage phosphor manufacturer and designation (k)image acquisition (digitizing) equipment manufac-
turer, model, and serial number (l) single- or double-wall exposure (m) single- or double-wall viewing
(n)procedure identification and revision level (o)imaging software version and revision
(p)numerical values of the final image processing para- meters, i.e., filters, window (contrast), and level (brightness) for each view
The technique details may be embedded in the data file.
When this is performed, ASTM E1475, Standard Guide for Data Fields for Computerized Transfer of Digital Radiolo- gical Test Data, may be used as a guide for establishing data fields and information content.
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MANDATORY APPENDIX IX