Measured water transmission curves and calculated zero field size tumor maximum ratios for 4, 6, and 15 MV x-rays

The development of computers and computer-controlled devices has, on the whole, had a profound impact on how things are accomplished in our industrialized society, and this is true for radiation therapy as well. In most issues of Medical Physics there are papers describing how computercontrolled accelerators and multi-leaf collimators used in combination with advanced treatmentplanning systems, which in turn require multiple CT or MRI scans, can produce more uniform and precisely defined dose distributions limited to the treatment volume, and thereby permit larger tumor doses. The inherent assumption underlying this so-called Conformal Therapy is that its introduction will result in higher cure rates: however, there is scant evidence to support this assumption, and it is possible that the reverse may be true. It is recommended that randomized/ prospective trials of this new technology be undertaken before it becomes so widespread that such an evaluation is no longer possible. © 1999 American Association of Physicists in Medicine. [80094-2405(99)02506-7]