Final answer:
Portable X-ray machines generally require longer exposure times due to their lower power sources, in contrast to fixed systems. X-rays are used over radio waves for imaging because of their higher penetrating energy, which is key for visualizing internal structures like bones. X-rays carry more energy than visible light, justifying the concern for exposure risks during medical imaging.
Step-by-step explanation:
Portable X-ray machines generally require longer exposure times to produce images compared to fixed X-ray systems because they tend to have less powerful radiation sources, meaning they need more time to obtain an image of similar quality. Portable X-ray units are also designed to minimize radiation exposure to patients, which is why they generate low-energy radiation to produce images, as is typically the case with dental X-ray machines. Exposure time can vary but is often set higher to compensate for the lower energy output. In terms of imaging, x-rays are used instead of radio waves because X-rays have higher penetrating energy than radio waves, allowing them to effectively image internal structures such as bones. The high energy of X-ray photons enables them to penetrate materials that are opaque to visible light and to provide clear images of physiological differences in density, which is crucial in detecting breaks in bones and other medical conditions. Concerning the safety of electromagnetic radiation, while x-ray photons and visible light are both forms of electromagnetic radiation, x-ray photons carry considerably more energy and can be harmful in large doses due to their ability to cause significant ionization and cell damage in biological tissues, which is not a concern with the low energies associated with visible light. Modern X-ray practices aim to minimize this exposure and shield others from the radiation produced during imaging.