A beryllium (Be) window on the x-ray tube is used primarily to enhance contrast by doing what?

The use of a beryllium window on the x-ray tube is primarily to transmit more low-energy photons, which is essential in mammography. This window material has specific properties that allow it to effectively transmit the lower-energy x-rays that are produced during the imaging process.

In mammography, low-energy photons are crucial because they contribute to the contrast of the images — especially in differentiating between the different types of breast tissue. Higher energy photons, conversely, can penetrate tissues too easily, leading to less contrast on the resulting images, making it difficult to detect subtle differences between malignant and benign tissues.

Beryllium is favored because it has a low atomic number and is thin enough to allow low-energy x-rays to pass through while still providing some filtration of higher-energy photons that could decrease image quality. This capability enhances the overall contrast of the images, allowing for better diagnostic outcomes in breast imaging.