Final answer:
The target of the anode in a mammography unit is typically made from molybdenum or rhodium, due to their effective characteristics in producing suitable X-ray photons for imaging soft breast tissue.
Step-by-step explanation:
In a mammography unit, the target of the anode is often made from molybdenum or rhodium. These materials are chosen for their ability to produce X-ray photons that are ideal for imaging the soft tissue of the breast, providing better contrast and resolution for the detection of small tumors.
The electrons in a mammography X-ray tube are accelerated towards the target material, striking it and producing X-ray photons. The material's higher atomic number and electron density ensure efficient X-ray production and appropriate tissue penetration. The range of the radiation is dependent on the material's properties, primarily its electron density. Materials with higher electron densities, like lead, are often used to shield against unwanted radiation exposure in various X-ray applications, including mammography.