Proton Beam Therapy vs. X-ray Beams（1）

   The problem with X-rays as an energy source is that they're not easy to control. They have a low mass and a high energy, making it difficult to direct exactly where and how they interact with body tissue. Most body tissue doesn't absorb or block X-rays, so they just keep moving right through the body, releasing energy. When an X-ray(by mobile x ray machine or c arm x ray machine) enters the body, it emits a tremendous amount of energy at the point of entrance. That's why X-ray treatment leaves people with a tan at the treatment site -- their skin is receiving a lot of radiation. As the X-ray continues into the body, it continues to release energy. As long as the cancer tumor is somewhere in the path of the X-ray, it receives some of that radiation. But so does the healthy tissue all around it. The tissue damage that results from this type of radiation therapy can cause serious problems for the patient if the tumor is in a particularly sensitive area like the brain, the eye, the lungs, spinal cord or liver. It can cause irreparable organ damage. And for children, any tissue damage can be detrimental to their development. In order to limit the extent of collateral tissue damage, oncologists will bombard the tumor area with the lowest level of effective radiation.
      Proton-beam therapy can avoid this type of collateral damage. Protons are positively charged atomic particles, and they have tremendous energy but also tremendous mass. They're easier to control than X-rays: They slow down as they encounter body tissue. Protons can actually be set to release their energy at a specific point in body.
      For details of x ray beam, we will put up it later!