A flare is defined as a sudden, rapid, and intense variation in brightness. A solar flare occurs when magnetic energy that has built up in the solar atmosphere is suddenly released. Radiation is emitted across virtually the entire electromagnetic spectrum, from radio waves at the long wavelength end, through optical emission to x-rays and gamma rays at the short wavelength end. The amount of energy released is the equivalent of millions of 100-megaton hydrogen bombs exploding at the same time! The first solar flare recorded in astronomical literature was on September 1, 1859.

In physics, the photon is the elementary particle responsible for electromagnetic phenomena. It is the carrier of electromagnetic radiation of all wavelengths, including gamma rays, X-rays, ultraviolet light, visible light, infrared light, microwaves, and radio waves.

Stereotactic radiosurgery is the very precise delivery of radiation to a brain tumor while sparing the surrounding normal brain tissue. Because it is so precise, stereotactic radiosurgery allows a higher dose of radiation to be given with more sparing of normal brain than can be achieved with conventional radiotherapy techniques.Information from MRI and/or CT scans are directly transferred to the treatment planning computer system to create a 3-D model of the tumor and surrounding normal brain. A complex radiation delivery planning system is utilized to target a high dose of radiation at the tumor while greatly limiting the dose to nearby normal brain. Special devices are used to keep the head still so that the radiation will be aimed with great accuracy at the targeted tumor.

Protons are atoms that carry a positive charge. Just as x-rays are used to treat both benign and malignant tumors, a beam of protons can be used to radiate tumors in the same way. There is essentially no biological difference between x-ray and protons, except that protons release most of their energy when they hit the tumor and deliver no exit dose beyond the tumor boundary. Therefore, the dose of radiation conforms to the tumor better and there is less damage to healthy tissue. As a result, the treating physician (a radiation oncologist) can give an even greater dose to the tumor while minimizing unwanted side effects. This is especially important when treating children, because it reduces radiation to growing and developing tissues.