What does the Bow-Tie filter effectively remove from the X-ray beam?

The Bow-Tie filter is designed primarily to modify the X-ray beam profile in a way that enhances image quality while minimizing patient exposure to radiation. Its unique shape allows it to preferentially attenuate low-energy X-rays, particularly the ones around 30 keV. These low-energy X-rays usually do not contribute significantly to image quality but can increase patient dose and contribute to noise in the final images. By effectively removing these low-energy X-rays from the beam, the Bow-Tie filter helps improve the overall diagnostic value of the images captured during procedures, such as in computed tomography (CT) or certain PET applications that utilize X-ray technologies. Thus, the effectiveness of the Bow-Tie filter lies in its ability to enhance contrast and reduce unnecessary radiation exposure to the patient by filtering out energy levels that do not contribute meaningfully to image formation.