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5.1 The only truly valid image quality indicator is a material or component, equivalent to the part being neutron radiographed, with a known standard discontinuity, inclusion, omission, or flaw (reference standard comparison part). The SI is designed to substitute for the reference standard, providing qualitative information on hole and gap sensitivity in a single unit. Fabrication in accordance with this practice is vital for accurate and consistent measurements.5.2 This practice shall be followed for the fabrication of all SIs to be used with Test Method E545 to determine image quality in direct thermal neutron radiography. Devices constructed to previous versions of this practice, or Test Method E545 for devices built between 1981 and 1991, can also be used.1.1 This practice covers the fabrication of Sensitivity Indicators (SI), which can be used to determine the relative quality of film radiographic images produced by direct, thermal neutron radiographic examination.1.2 Units—The values stated in inch-pound units are to be regarded as standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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3.1 Expiration dates are often marked on the packages of perishable products to indicate the presumed end of their shelf lives. Since the shelf lives of most perishable products are temperature dependent, the expiration date is determined by assuming the product will be kept within a prescribed temperature range for its entire life. A problem with this method is that there is no way to determine if the shelf life of a product has been shortened by exposure to a higher temperature. A time-temperature indicator solves this problem when attached to the package because it reaches its end point sooner when exposed to a higher temperature.3.2 In order to directly indicate the end of the shelf life, the time-temperature indicator characteristics should be matched as closely as possible to the quality characteristics of the product. When kept at the standard storage temperature for the product, the indicator should reach its end point at the same time as the product's shelf life. In addition, to determine the accuracy of the match at other temperatures, the change of shelf life with temperature should be known for both the product and the indicator. The Arrhenius relationship is a common and convenient method of describing the change of shelf life with temperature. In cases where it is not applicable, individual time-temperature points for the product may be established and an approximate correlation with the TTI obtained.3.3 When attached to the package of a perishable product, a time-temperature indicator may supplement, or in some cases replace, the expiration date code. The addition of a TTI provides a greater level of confidence that the perishable product is within its shelf life because it responds to the actual temperature conditions to which the product has been exposed.3.4 In the case of minimally processed refrigerated foods, the rapid growth of pathogenic bacteria at elevated temperatures may pose a serious health hazard even before the deterioration of the quality of the product becomes apparent to the consumer. In this case, an expiration date may be used for storage at the standard temperature, while a threshold-temperature TTI is used to indicate the exposure to temperatures at which growth becomes measurable. It is also possible to use a dual-function TTI, in which case the standard TTI would indicate the shelf life at the correct storage temperature while the threshold-temperature part would indicate the exposure to higher temperatures.1.1 This guide covers information on the selection of commercially available time-temperature indicators (TTIs) for noninvasive external package use on perishable products, such as food and pharmaceuticals. When attached to the package of a perishable product, TTIs are used to measure the combined time and temperature history of the product in order to predict the remaining shelf life of the product or to signal the end of its usable shelf life. It is the responsibility of the processor of the perishable product to determine the shelf life of a product at the appropriate temperatures and to consult with the indicator manufacturer to select the available indicator which most closely matches the quality of the product as a function of time and temperature.NOTE 1: Besides time-temperature indicator, TTI is also an abbreviation for time-temperature monitor and time-temperature integrator.1.2 Time-temperature indicators may be integrated into a Hazard Analysis and Critical Control Point (HACCP) plan. Appropriate instructions should be established for handling products for which either the indicator has signaled the end of usable shelf life or the shelf life of the product at its normal storage temperature has been reached.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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4.1 Indicators may be used to show that products have been exposed to a radiation source. They should be used only to provide a qualitative indication of radiation exposure and may be used to distinguish process loads that have been irradiated from unirradiated loads.NOTE 1: The use of indicators does not eliminate the need for other process-control procedures, such as quantitative dosimetry or the controlled segregation of irradiated from nonirradiated products.NOTE 2: See ISO/ASTM Standards 51608, 51649, 51702, 51939, and 51940 for information on the use of indicators in the various types of processing facilities and for unique product applications.4.2 The indicator manufacturer is obliged to supply a statement regarding the approximate dose level at which the examiner (20/20 vision), at standard illumination (unfiltered daylight, or artificial light of the spectrum and intensity defined by the proper ASTM standard), is able to determine the visual change in the indicator.1.1 This document covers procedures for using radiation-sensitive indicators (referred to hereafter as indicators) in radiation processing. These indicators may be labels, papers, inks or packaging materials which undergo a visual change when exposed to ionizing radiation (1-5).21.2 The purpose for using indicators is to determine visually whether or not a product has been irradiated, rather than to measure different dose levels.1.3 Indicators are not dosimeters and should not be used as a substitute for proper dosimetry. Information about dosimetry systems for radiation processing is provided in other ASTM and ISO/ASTM documents (see ISO/ASTM Guide 51261).1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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5.1 The BPI is designed to yield quantitative information concerning neutron beam and image system parameters that contribute to film exposure and, thereby, affect overall image quality. For proper measurements of film exposure due to the neutron beam constituents, the BPI must be fabricated in accordance with this practice.5.2 This practice shall be followed for the fabrication of all Beam Purity Indicators to be used with Test Method E545 to determine image quality in direct thermal neutron radiography.1.1 This practice covers the material and fabrication of a Beam Purity Indicator (BPI), which can be used to determine the relative quality of radiographic images produced by direct, thermal neutron radiographic examination.1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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5.1 The use of RQIs is a significant departure from normal practice in industrial radiology because it is not a standard design and is dependent on the application, material, and process and therefore cannot be a simple plaque or wire. The use of an RQI provides documented evidence that radiologic images have the level of quality necessary to reveal those nonconformances for which the parts are being examined by ensuring adequate spatial resolution and contrast sensitivity in the areas of interest.5.2 Where conventional IQIs conforming to Practice E747 or E1025 can be used effectively, those practices should be followed.1.1 This practice covers the radiological examination of unique materials or processes, or both, for which conventionally designed image quality indicators (IQIs), such as those described in Practices E747 and E1025, may be inadequate in controlling the quality and repeatability of the radiological image.1.2 Where appropriate, representative image quality indicators (RQIs) may also represent criteria levels of the acceptance or rejection of images of discontinuities.1.3 This practice is applicable to most radiological methods of examination.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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