The survival curves for this clinical trial are very good, and this was for people with inoperable tumors which makes it much more impressive. The concept is they give a dye - 5-Ala - to the patient. The dye gets taken up by tumor cells much more than normal cells. This dye is FDA approved as Gliolan for use during surgery so the surgeon can tell tumor from non tumor. However, they found that when the dye is excited by light (or by ultrasound when used with Sonodynamic therapy), it kills the cells that take up the dye and leave the normal cells mostly alone. They use fiber optics to deliver the light through a small bur hole in the skull. We do not yet have results for sonodynamic therapy but they have to be compared to this to see which way is better. Sonodynamic therapy is non invasive, and has the advantage of being able to treat large areas of the brain, wheras photodynamic therapy requires direct access to the area.