Can you trust grey values alone as an indication of X-ray penetration?

When performing Digital Radiography (DR) and Computed Tomography (CT) it’s easy to misinterpret a specific grey value within the DR image as indication of X-ray penetration. This can often be an accurate judgment, however, the grey value may frequently be falsely elevated due to scatter radiation. To assure the product is truly being penetrated, don’t trust grey values alone. For a complex product one can look for features within the product that show up within the image in the area of the highest attenuation. These feature edges can serve as an indication of penetration for that area. A more conclusive approach is to place a high density wire or object (Tungsten, Lead, Copper etc.) across the area in question. If complete penetration of the product has occurred, the outline of the high density material should be visible across the entire high attenuation area. Tungsten electrodes used in TIG welding work great for this task.