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Radiation Dose to an Internal Component

The advent of digital radiography and high-speed cone beam computed tomography for routine nondestructive testing has revolutionized industrial inspection and quality assurance programs over the past decade. While exposure time for a single digital radiography image is typically much less than that required to obtain a comparable film-screen image, the large number of sequential digital radiography images generated during today’s digital radiography and computed tomography inspections can result in significantly higher overall radiation dosage as compared to when film screen was the standard radiographic technique. Knowing the internal dose received by both the digital X-ray panel and the individual internal components in a part under inspection can help avoid unexpected damage and assist in performing failure analysis. This paper reviews the source-to-surface technique to manually calculate radiation dose at an internal interface for source energies in the megaelectronvolt range, typical of those encountered when testing larger industrial objects, and provides examples demonstrating the calculation of the various parameters required. A future paper will discuss required modifications for applications in the kilovolt range.

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