What device is used to eliminate long-wavelength radiation from the primary X-ray beam?

The device that is used to eliminate long-wavelength radiation from the primary X-ray beam is a filter. In the context of X-ray imaging, filters are employed to selectively absorb lower-energy photons that do not contribute to image formation but rather contribute to patient dose. The long-wavelength X-rays are generally less penetrating and produce scatter, which does not improve image quality.

By placing a filter in the path of the X-ray beam, typically made of aluminum or other materials with similar properties, these less useful long-wavelength photons are absorbed, allowing only the higher-energy photons to pass through. This results in a higher quality image with reduced patient exposure to unnecessary radiation.

The collimator can restrict the size and shape of the X-ray beam but does not specifically target long-wavelength radiation. A condenser relates to focusing light rather than filtering X-rays, and a transformer is used to change the voltage in the X-ray circuit, not to filter X-rays. Thus, the filter serves a crucial role in enhancing the safety and effectiveness of X-ray imaging by ensuring that only useful radiation contributes to the diagnostic image.