Independent evaluations of IMRT through the use of an anthropomorphic phantom.

Intensity-modulated radiation therapy (IMRT) has gained rapid and wide-spread acceptance in the radiation oncology community for its ability to create dose distributions that conform to the convoluted shapes of many tumors. It is a complicated treatment technique, for which quality assurance procedures are correspondingly complicated and labor intensive. Several of the cooperative cancer study groups that conduct clinical trials under the auspices of the National Cancer Institute have required participating institutions to seek credentialing before enrolling patients in trials involving IMRT. The Radiological Physics Center has conducted such credentialing programs through the use of anthropomorphic phantoms that evaluate the planning and delivery of IMRT. The experience obtained through the irradiation of the phantoms by a number of institutions demonstrates that institutions vary significantly in their ability to deliver doses and dose distributions that agree with their own treatment plans.