Why and how the γ-prox proximity gamma-graphy control makes possible the decrease of beaconing distances?

After having commented the benefit of using X-ray radiography instead of gamma-graphy in some cases, the author discusses the different mechanisms which interact for dose rates during a control operation performed by gamma-graphy. He first addresses the theoretical aspects: influencing parameters and radiation protection, radio-elements used in gamma-graphy (Cobalt 60, Iridium 192 and Selenium 75) and radiation rate. He discusses issues related to image quality, exposure time and film system used in industrial radiography, and notably compares the results obtained with the different radio-elements. He discusses the factors influencing the assessment of gamma radiation attenuation (screen material and thickness, source energy spectrum)