What is 'geometric unsharpness' in radiographic testing?

Geometric unsharpness refers to the blurring or lack of sharpness of an image that is primarily caused by the distance between the radiation source and the object being imaged as well as between the object and the film or detection device. When the distance increases, the x-ray rays diverge more as they travel to the object and then to the film, resulting in a less defined edge on the radiograph. This phenomenon can lead to a loss of detail in the image, particularly around the edges of the object, which is crucial for assessing size, shape, and integrity in radiographic tests. Understanding geometric unsharpness is essential in radiography as it allows technicians to optimize their techniques to minimize blurring and improve image contrast and clarity, thereby enabling more accurate inspections and assessments.