What device is used to measure the amount of inherent filtration in the x-ray beam?

The device used to measure the amount of inherent filtration in the x-ray beam is a dosimeter. Dosimeters are designed to measure ionizing radiation exposure, and in the context of x-ray equipment, they can be calibrated to assess the quality of the x-ray beam including the effects of filtration. Inherent filtration consists of the materials that devices like x-ray tubes are made of which attenuate or filter out lower energy x-rays from the beam.

By using a dosimeter, operators can determine how much of the low-energy radiation is being filtered out which directly impacts the quality of the x-ray that reaches the patient or the imaging receptor. This measurement is crucial for ensuring safety, optimizing image quality, and complying with regulatory standards.

Other devices mentioned, like the Geiger counter, are primarily used for detecting and measuring ionizing radiation in a more general sense, often in environmental settings rather than specifically measuring filtration in x-ray beams. A thermometer is unrelated, measuring temperature rather than radiation. A photometer is used largely for measuring light intensity, also not applicable in measuring x-ray beam filtration. Thus, the dosimeter stands out as the appropriate tool for this specific application in radiography.